From 4494dd58fbb477e54c129c1d8ef477aad433eba0 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 22 Apr 2019 12:17:45 -0400 Subject: tools/memory-model: Prepare for data-race detection This patch makes some slight alterations to linux-kernel.cat in preparation for adding support for data-race detection to the Linux-Kernel Memory Model. The definitions of relations involved in Acquire, Release, and unlock-lock ordering are moved up earlier in the source file. The rmb relation is factored through the new R4rmb class: the class of reads to which rmb will apply. The definition of the fence relation is moved earlier, and it is split up into read- and write-fences (rmb and wmb) and all the others. This should not make any functional changes. Signed-off-by: Alan Stern Reviewed-by: Andrea Parri Signed-off-by: Paul E. McKenney --- tools/memory-model/linux-kernel.cat | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'tools') diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index 8dcb37835b61..834107022c50 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -24,8 +24,14 @@ include "lock.cat" (* Basic relations *) (*******************) +(* Release Acquire *) +let acq-po = [Acquire] ; po ; [M] +let po-rel = [M] ; po ; [Release] +let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po + (* Fences *) -let rmb = [R \ Noreturn] ; fencerel(Rmb) ; [R \ Noreturn] +let R4rmb = R \ Noreturn (* Reads for which rmb works *) +let rmb = [R4rmb] ; fencerel(Rmb) ; [R4rmb] let wmb = [W] ; fencerel(Wmb) ; [W] let mb = ([M] ; fencerel(Mb) ; [M]) | ([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) | @@ -34,13 +40,10 @@ let mb = ([M] ; fencerel(Mb) ; [M]) | ([M] ; po ; [UL] ; (co | po) ; [LKW] ; fencerel(After-unlock-lock) ; [M]) let gp = po ; [Sync-rcu | Sync-srcu] ; po? - let strong-fence = mb | gp -(* Release Acquire *) -let acq-po = [Acquire] ; po ; [M] -let po-rel = [M] ; po ; [Release] -let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po +let nonrw-fence = strong-fence | po-rel | acq-po +let fence = nonrw-fence | wmb | rmb (**********************************) (* Fundamental coherence ordering *) @@ -63,7 +66,6 @@ let rwdep = (dep | ctrl) ; [W] let overwrite = co | fr let to-w = rwdep | (overwrite & int) let to-r = addr | (dep ; rfi) -let fence = strong-fence | wmb | po-rel | rmb | acq-po let ppo = to-r | to-w | fence | (po-unlock-rf-lock-po & int) (* Propagation: Ordering from release operations and strong fences. *) -- cgit v1.2.3 From d1a84ab190137cc2a980b6979b1f2790d51b2d87 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 22 Apr 2019 12:17:58 -0400 Subject: tools/memory-model: Add definitions of plain and marked accesses This patch adds definitions for marked and plain accesses to the Linux-Kernel Memory Model. It also modifies the definitions of the existing parts of the model (including the cumul-fence, prop, hb, pb, and rb relations) so as to make them apply only to marked accesses. Signed-off-by: Alan Stern Reviewed-by: Andrea Parri Signed-off-by: Paul E. McKenney --- tools/memory-model/linux-kernel.bell | 5 +++++ tools/memory-model/linux-kernel.cat | 16 +++++++++------- 2 files changed, 14 insertions(+), 7 deletions(-) (limited to 'tools') diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell index def9131d3d8e..b60eb5a01053 100644 --- a/tools/memory-model/linux-kernel.bell +++ b/tools/memory-model/linux-kernel.bell @@ -76,3 +76,8 @@ flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep (* Validate SRCU dynamic match *) flag ~empty different-values(srcu-rscs) as srcu-bad-nesting + +(* Compute marked and plain memory accesses *) +let Marked = (~M) | IW | Once | Release | Acquire | domain(rmw) | range(rmw) | + LKR | LKW | UL | LF | RL | RU +let Plain = M \ Marked diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index 834107022c50..ff354e5ffd4b 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -65,19 +65,21 @@ let dep = addr | data let rwdep = (dep | ctrl) ; [W] let overwrite = co | fr let to-w = rwdep | (overwrite & int) -let to-r = addr | (dep ; rfi) +let to-r = addr | (dep ; [Marked] ; rfi) let ppo = to-r | to-w | fence | (po-unlock-rf-lock-po & int) (* Propagation: Ordering from release operations and strong fences. *) -let A-cumul(r) = rfe? ; r -let cumul-fence = A-cumul(strong-fence | po-rel) | wmb | po-unlock-rf-lock-po -let prop = (overwrite & ext)? ; cumul-fence* ; rfe? +let A-cumul(r) = (rfe ; [Marked])? ; r +let cumul-fence = [Marked] ; (A-cumul(strong-fence | po-rel) | wmb | + po-unlock-rf-lock-po) ; [Marked] +let prop = [Marked] ; (overwrite & ext)? ; cumul-fence* ; + [Marked] ; rfe? ; [Marked] (* * Happens Before: Ordering from the passage of time. * No fences needed here for prop because relation confined to one process. *) -let hb = ppo | rfe | ((prop \ id) & int) +let hb = [Marked] ; (ppo | rfe | ((prop \ id) & int)) ; [Marked] acyclic hb as happens-before (****************************************) @@ -85,7 +87,7 @@ acyclic hb as happens-before (****************************************) (* Propagation: Each non-rf link needs a strong fence. *) -let pb = prop ; strong-fence ; hb* +let pb = prop ; strong-fence ; hb* ; [Marked] acyclic pb as propagation (*******) @@ -133,7 +135,7 @@ let rec rcu-fence = rcu-gp | srcu-gp | (rcu-fence ; rcu-link ; rcu-fence) (* rb orders instructions just as pb does *) -let rb = prop ; po ; rcu-fence ; po? ; hb* ; pb* +let rb = prop ; po ; rcu-fence ; po? ; hb* ; pb* ; [Marked] irreflexive rb as rcu -- cgit v1.2.3 From 0031e38adf38779acce5737f4905b9f60750b674 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 22 Apr 2019 12:18:09 -0400 Subject: tools/memory-model: Add data-race detection This patch adds data-race detection to the Linux-Kernel Memory Model. As part of this effort, support is added for: compiler barriers (the barrier() function), and a new Preserved Program Order term: (addr ; [Plain] ; wmb) Data races are marked with a special Flag warning in herd. It is not guaranteed that the model will provide accurate predictions when a data race is present. The patch does not include documentation for the data-race detection facility. The basic design has been explained in various emails, and a separate documentation patch will be submitted later. This work is based on an earlier formulation of data races for the LKMM by Andrea Parri. Signed-off-by: Alan Stern Reviewed-by: Andrea Parri Signed-off-by: Paul E. McKenney --- tools/memory-model/linux-kernel.bell | 1 + tools/memory-model/linux-kernel.cat | 50 +++++++++++++++++++++++++++++++++++- tools/memory-model/linux-kernel.def | 1 + 3 files changed, 51 insertions(+), 1 deletion(-) (limited to 'tools') diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell index b60eb5a01053..5be86b1025e8 100644 --- a/tools/memory-model/linux-kernel.bell +++ b/tools/memory-model/linux-kernel.bell @@ -24,6 +24,7 @@ instructions RMW[{'once,'acquire,'release}] enum Barriers = 'wmb (*smp_wmb*) || 'rmb (*smp_rmb*) || 'mb (*smp_mb*) || + 'barrier (*barrier*) || 'rcu-lock (*rcu_read_lock*) || 'rcu-unlock (*rcu_read_unlock*) || 'sync-rcu (*synchronize_rcu*) || diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index ff354e5ffd4b..36d367054811 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -44,6 +44,9 @@ let strong-fence = mb | gp let nonrw-fence = strong-fence | po-rel | acq-po let fence = nonrw-fence | wmb | rmb +let barrier = fencerel(Barrier | Rmb | Wmb | Mb | Sync-rcu | Sync-srcu | + Before-atomic | After-atomic | Acquire | Release) | + (po ; [Release]) | ([Acquire] ; po) (**********************************) (* Fundamental coherence ordering *) @@ -64,7 +67,7 @@ empty rmw & (fre ; coe) as atomic let dep = addr | data let rwdep = (dep | ctrl) ; [W] let overwrite = co | fr -let to-w = rwdep | (overwrite & int) +let to-w = rwdep | (overwrite & int) | (addr ; [Plain] ; wmb) let to-r = addr | (dep ; [Marked] ; rfi) let ppo = to-r | to-w | fence | (po-unlock-rf-lock-po & int) @@ -147,3 +150,48 @@ irreflexive rb as rcu * let xb = hb | pb | rb * acyclic xb as executes-before *) + +(*********************************) +(* Plain accesses and data races *) +(*********************************) + +(* Warn about plain writes and marked accesses in the same region *) +let mixed-accesses = ([Plain & W] ; (po-loc \ barrier) ; [Marked]) | + ([Marked] ; (po-loc \ barrier) ; [Plain & W]) +flag ~empty mixed-accesses as mixed-accesses + +(* Executes-before and visibility *) +let xbstar = (hb | pb | rb)* +let full-fence = strong-fence | (po ; rcu-fence ; po?) +let vis = cumul-fence* ; rfe? ; [Marked] ; + ((full-fence ; [Marked] ; xbstar) | (xbstar & int)) + +(* Boundaries for lifetimes of plain accesses *) +let w-pre-bounded = [Marked] ; (addr | fence)? +let r-pre-bounded = [Marked] ; (addr | nonrw-fence | + ([R4rmb] ; fencerel(Rmb) ; [~Noreturn]))? +let w-post-bounded = fence? ; [Marked] +let r-post-bounded = (nonrw-fence | ([~Noreturn] ; fencerel(Rmb) ; [R4rmb]))? ; + [Marked] + +(* Visibility and executes-before for plain accesses *) +let ww-vis = w-post-bounded ; vis ; w-pre-bounded +let wr-vis = w-post-bounded ; vis ; r-pre-bounded +let rw-xbstar = r-post-bounded ; xbstar ; w-pre-bounded + +(* Potential races *) +let pre-race = ext & ((Plain * M) | ((M \ IW) * Plain)) + +(* Coherence requirements for plain accesses *) +let wr-incoh = pre-race & rf & rw-xbstar^-1 +let rw-incoh = pre-race & fr & wr-vis^-1 +let ww-incoh = pre-race & co & ww-vis^-1 +empty (wr-incoh | rw-incoh | ww-incoh) as plain-coherence + +(* Actual races *) +let ww-nonrace = ww-vis & ((Marked * W) | rw-xbstar) & ((W * Marked) | wr-vis) +let ww-race = (pre-race & co) \ ww-nonrace +let wr-race = (pre-race & (co? ; rf)) \ wr-vis +let rw-race = (pre-race & fr) \ rw-xbstar + +flag ~empty (ww-race | wr-race | rw-race) as data-race diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def index 551eeaa389d4..ef0f3c1850de 100644 --- a/tools/memory-model/linux-kernel.def +++ b/tools/memory-model/linux-kernel.def @@ -24,6 +24,7 @@ smp_mb__before_atomic() { __fence{before-atomic}; } smp_mb__after_atomic() { __fence{after-atomic}; } smp_mb__after_spinlock() { __fence{after-spinlock}; } smp_mb__after_unlock_lock() { __fence{after-unlock-lock}; } +barrier() { __fence{barrier}; } // Exchange xchg(X,V) __xchg{mb}(X,V) -- cgit v1.2.3 From e0e2147c1a6a722f6b2e359c5132a825ecb8a420 Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Tue, 26 Mar 2019 15:24:10 -0400 Subject: rcutorture: Select from only online CPUs The rcutorture jitter.sh script selects a random CPU but does not check if it is offline or online. This leads to taskset errors many times. On my machine, hyper threading is disabled so half the cores are offline causing taskset errors a lot of times. Let us fix this by checking from only the online CPUs on the system. Cc: rcu@vger.kernel.org Signed-off-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/jitter.sh | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh index 435b60933985..81c6e6ab5d83 100755 --- a/tools/testing/selftests/rcutorture/bin/jitter.sh +++ b/tools/testing/selftests/rcutorture/bin/jitter.sh @@ -34,10 +34,11 @@ do exit 0; fi - # Set affinity to randomly selected CPU - cpus=`ls /sys/devices/system/cpu/*/online | + # Set affinity to randomly selected online CPU + cpus=`grep 1 /sys/devices/system/cpu/*/online | sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' | grep -v '^0*$'` + cpumask=`awk -v cpus="$cpus" -v me=$me -v n=$n 'BEGIN { srand(n + me + systime()); ncpus = split(cpus, ca); -- cgit v1.2.3 From dd064c35991435efc4da2a6c551601f6e80f2611 Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Tue, 26 Mar 2019 15:24:11 -0400 Subject: rcutorture: Add cpu0 to the set of CPUs to add jitter jitter.sh currently does not add CPU0 to the list of CPUs for adding of jitter. Let us add it to this list even when it is not hot-pluggable. Signed-off-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/jitter.sh | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh index 81c6e6ab5d83..dc49a3ba6111 100755 --- a/tools/testing/selftests/rcutorture/bin/jitter.sh +++ b/tools/testing/selftests/rcutorture/bin/jitter.sh @@ -36,8 +36,12 @@ do # Set affinity to randomly selected online CPU cpus=`grep 1 /sys/devices/system/cpu/*/online | - sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//' | - grep -v '^0*$'` + sed -e 's,/[^/]*$,,' -e 's/^[^0-9]*//'` + + # Do not leave out poor old cpu0 which may not be hot-pluggable + if [ ! -f "/sys/devices/system/cpu/cpu0/online" ]; then + cpus="0 $cpus" + fi cpumask=`awk -v cpus="$cpus" -v me=$me -v n=$n 'BEGIN { srand(n + me + systime()); -- cgit v1.2.3 From 63b29eaed6f57c27639b2954ac1f202409840abf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 11 Apr 2019 13:31:57 -0700 Subject: torture: Make kvm-find-errors.sh and kvm-recheck.sh provide exit status This commit causes both kvm-find-errors.sh and kvm-recheck.sh to provide an exit status based on whether or not errors were located. In the case of kvm-recheck.sh, this will be the error status of the last run. This change allows these commands to be used in scripting and Makefiles to automatically report failed rcutorture runs. Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh | 3 +++ tools/testing/selftests/rcutorture/bin/kvm-recheck.sh | 3 +++ 2 files changed, 6 insertions(+) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh index 8426fe1f15ee..1871d00bccd7 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-find-errors.sh @@ -11,6 +11,7 @@ # # The "directory" above should end with the date/time directory, for example, # "tools/testing/selftests/rcutorture/res/2018.02.25-14:27:27". +# Returns error status reflecting the success (or not) of the specified run. # # Copyright (C) IBM Corporation, 2018 # @@ -56,6 +57,8 @@ done if test -n "$files" then $editor $files + exit 1 else echo No errors in console logs. + exit 0 fi diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh index 2adde6aaafdb..2297ddc2d4c5 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh @@ -7,6 +7,8 @@ # # Usage: kvm-recheck.sh resdir ... # +# Returns status reflecting the success or not of the last run specified. +# # Copyright (C) IBM Corporation, 2011 # # Authors: Paul E. McKenney @@ -58,3 +60,4 @@ do fi done done +EDITOR=echo kvm-find-errors.sh "${@: -1}" > /dev/null 2>&1 -- cgit v1.2.3 From 2456a8562b296453b4cdce8b6928e3f91e39fefc Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 11 Apr 2019 14:51:13 -0700 Subject: rcutorture: Provide rudimentary Makefile This commit provides a rudimentary Makefile that runs a 10-minute rcutorture test on scenario TREE01. This must be run on a system capable of spawning virtual machines and with everything installed to permit building Linux kernels. Reported-by: Shuah Khan Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/Makefile | 3 +++ 1 file changed, 3 insertions(+) create mode 100644 tools/testing/selftests/rcutorture/Makefile (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/Makefile b/tools/testing/selftests/rcutorture/Makefile new file mode 100644 index 000000000000..5202dc666206 --- /dev/null +++ b/tools/testing/selftests/rcutorture/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0+ +all: + ( cd ../../../..; tools/testing/selftests/rcutorture/bin/kvm.sh --duration 10 --configs TREE01 ) -- cgit v1.2.3 From 52b23be7ee023d7f1b67e7a20443ef352c7b5d2d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 13 Apr 2019 15:41:49 -0700 Subject: rcutorture: Exempt TREE01 from forward-progress testing Because TREE01 can end up running more vCPUs that physical CPUs, hammering these shortchanged CPUs with tight loops containing call_rcu() invocations seems a bit like overkill. This commit therefore exempts TREE01 from rcutorture's forward-progress testing. Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot | 1 + 1 file changed, 1 insertion(+) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot index ea47da95374b..d6da9a61d44a 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot @@ -3,3 +3,4 @@ rcutree.gp_preinit_delay=3 rcutree.gp_init_delay=3 rcutree.gp_cleanup_delay=3 rcu_nocbs=0 +rcutorture.fwd_progress=0 -- cgit v1.2.3 From c682db558e6eec10a711b0a6bcb8c35fd15f6a39 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 19 Apr 2019 07:38:27 -0700 Subject: rcutorture: Add trivial RCU implementation I have been showing off a trivial RCU implementation for non-preemptive environments for some time now: #define rcu_read_lock() #define rcu_read_unlock() #define rcu_dereference(p) READ_ONCE(p) #define rcu_assign_pointer(p, v) smp_store_release(&(p), (v)) void synchronize_rcu(void) { int cpu; for_each_online_cpu(cpu) sched_setaffinity(current->pid, cpumask_of(cpu)); } Trivial or not, as the old saying goes, "if it ain't tested, it don't work!". This commit therefore adds a "trivial" flavor to rcutorture and a corresponding TRIVIAL test scenario. This variant does not handle CPU hotplug, which is unconditionally enabled on x86 for post-v5.1-rc3 kernels, which is why the TRIVIAL.boot says "rcutorture.onoff_interval=0". This commit actually does handle CONFIG_PREEMPT=y kernels, but only because it turns back the Linux-kernel clock in order to provide these alternative definitions (or the moral equivalent thereof): #define rcu_read_lock() preempt_disable() #define rcu_read_unlock() preempt_enable() In CONFIG_PREEMPT=n kernels without debugging, these are equivalent to empty macros give or take a compiler barrier. However, the have been successfully tested with actual empty macros as well. Signed-off-by: Paul E. McKenney [ paulmck: Fix symbol issue reported by kbuild test robot . ] [ paulmck: Work around sched_setaffinity() issue noted by Andrea Parri. ] [ paulmck: Add rcutorture.shuffle_interval=0 to TRIVIAL.boot to fix interaction with shuffler task noted by Peter Zijlstra. ] Tested-by: Andrea Parri --- kernel/rcu/rcu.h | 5 +++ kernel/rcu/rcutorture.c | 45 +++++++++++++++++++++- kernel/rcu/update.c | 13 +++++++ .../selftests/rcutorture/configs/rcu/TRIVIAL | 14 +++++++ .../selftests/rcutorture/configs/rcu/TRIVIAL.boot | 3 ++ 5 files changed, 79 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL create mode 100644 tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot (limited to 'tools') diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 390aab20115e..5290b01de534 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -446,6 +446,7 @@ void rcu_request_urgent_qs_task(struct task_struct *t); enum rcutorture_type { RCU_FLAVOR, RCU_TASKS_FLAVOR, + RCU_TRIVIAL_FLAVOR, SRCU_FLAVOR, INVALID_RCU_FLAVOR }; @@ -479,6 +480,10 @@ void do_trace_rcu_torture_read(const char *rcutorturename, #endif #endif +#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) +long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask); +#endif + #ifdef CONFIG_TINY_SRCU static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index a3f5488a319a..6b803fb2f7ca 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -672,6 +672,47 @@ static struct rcu_torture_ops tasks_ops = { .name = "tasks" }; +/* + * Definitions for trivial CONFIG_PREEMPT=n-only torture testing. + * This implementation does not necessarily work well with CPU hotplug. + */ + +static void synchronize_rcu_trivial(void) +{ + int cpu; + + for_each_online_cpu(cpu) { + rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu)); + WARN_ON_ONCE(raw_smp_processor_id() != cpu); + } +} + +static int rcu_torture_read_lock_trivial(void) __acquires(RCU) +{ + preempt_disable(); + return 0; +} + +static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU) +{ + preempt_enable(); +} + +static struct rcu_torture_ops trivial_ops = { + .ttype = RCU_TRIVIAL_FLAVOR, + .init = rcu_sync_torture_init, + .readlock = rcu_torture_read_lock_trivial, + .read_delay = rcu_read_delay, /* just reuse rcu's version. */ + .readunlock = rcu_torture_read_unlock_trivial, + .get_gp_seq = rcu_no_completed, + .sync = synchronize_rcu_trivial, + .exp_sync = synchronize_rcu_trivial, + .fqs = NULL, + .stats = NULL, + .irq_capable = 1, + .name = "trivial" +}; + static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old) { if (!cur_ops->gp_diff) @@ -1789,6 +1830,8 @@ static void rcu_torture_fwd_prog_cr(void) if (READ_ONCE(rcu_fwd_emergency_stop)) return; /* Get out of the way quickly, no GP wait! */ + if (!cur_ops->call) + return; /* Can't do call_rcu() fwd prog without ->call. */ /* Loop continuously posting RCU callbacks. */ WRITE_ONCE(rcu_fwd_cb_nodelay, true); @@ -2265,7 +2308,7 @@ rcu_torture_init(void) int firsterr = 0; static struct rcu_torture_ops *torture_ops[] = { &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops, - &busted_srcud_ops, &tasks_ops, + &busted_srcud_ops, &tasks_ops, &trivial_ops, }; if (!torture_init_begin(torture_type, verbose)) diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index c3bf44ba42e5..61df2bf08563 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -423,6 +423,19 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); do { } while (0) #endif +#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) +/* Get rcutorture access to sched_setaffinity(). */ +long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask) +{ + int ret; + + ret = sched_setaffinity(pid, in_mask); + WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret); + return ret; +} +EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity); +#endif + #ifdef CONFIG_RCU_STALL_COMMON int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL new file mode 100644 index 000000000000..4d8eb5bfb6f6 --- /dev/null +++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL @@ -0,0 +1,14 @@ +CONFIG_SMP=y +CONFIG_NR_CPUS=8 +CONFIG_PREEMPT_NONE=y +CONFIG_PREEMPT_VOLUNTARY=n +CONFIG_PREEMPT=n +CONFIG_HZ_PERIODIC=n +CONFIG_NO_HZ_IDLE=y +CONFIG_NO_HZ_FULL=n +CONFIG_HOTPLUG_CPU=n +CONFIG_SUSPEND=n +CONFIG_HIBERNATION=n +CONFIG_DEBUG_LOCK_ALLOC=n +CONFIG_DEBUG_OBJECTS_RCU_HEAD=n +CONFIG_RCU_EXPERT=y diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot new file mode 100644 index 000000000000..7017f5f5a55f --- /dev/null +++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot @@ -0,0 +1,3 @@ +rcutorture.torture_type=trivial +rcutorture.onoff_interval=0 +rcutorture.shuffle_interval=0 -- cgit v1.2.3 From a6fda6dab93c2c06ef4b8cb4b9258df6674d2438 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 24 Apr 2019 09:34:46 +0200 Subject: rcutorture: Tweak kvm options In one of my rcutorture tests the TSC clocksource got marked unstable due to a large difference in the TSC value. I'm not sure if the guest run for a long time with disabled interrupts or if the host was very busy and didn't schedule the guest for some time. I took a look on the qemu/KVM options and decided to update the options: - Use kvm{32|64} as CPU. We could probably use `host' (like ARM does) for maximum available features but since we don't run any userland I'm not sure if it makes any difference. - Drop the "noapic" option. There is no history why the APIC was disabled, I see no reason for it. Once old qemu versions fade away, we can add "x2apic=on,tsc-deadline=on,hypervisor=on,tsc_adjust=on". - Additional config options. It ensures that the kernel knowns that it runs as a kvm guest and can use virt devices like the kvm-clock as clocksource. The kvm-clock was the main motivation here. - I didn't add a random HW device. It would make the random device ready earlier (not it doesn't complete the initialisation at all) but I doubt that there is any need for this. Signed-off-by: Sebastian Andrzej Siewior [ paulmck: The world is not quite ready for CONFIG_PARAVIRT_SPINLOCKS=y and x2apic, so they are omitted for the time being. ] Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/functions.sh | 13 ++++++++++++- tools/testing/selftests/rcutorture/configs/rcu/CFcommon | 3 +++ 2 files changed, 15 insertions(+), 1 deletion(-) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh index 6bcb8b5b2ff2..c3a49fb4d6f6 100644 --- a/tools/testing/selftests/rcutorture/bin/functions.sh +++ b/tools/testing/selftests/rcutorture/bin/functions.sh @@ -172,7 +172,7 @@ identify_qemu_append () { local console=ttyS0 case "$1" in qemu-system-x86_64|qemu-system-i386) - echo noapic selinux=0 initcall_debug debug + echo selinux=0 initcall_debug debug ;; qemu-system-aarch64) console=ttyAMA0 @@ -191,8 +191,19 @@ identify_qemu_append () { # Output arguments for qemu arguments based on the TORTURE_QEMU_MAC # and TORTURE_QEMU_INTERACTIVE environment variables. identify_qemu_args () { + local KVM_CPU="" + case "$1" in + qemu-system-x86_64) + KVM_CPU=kvm64 + ;; + qemu-system-i386) + KVM_CPU=kvm32 + ;; + esac case "$1" in qemu-system-x86_64|qemu-system-i386) + echo -machine q35,accel=kvm + echo -cpu ${KVM_CPU} ;; qemu-system-aarch64) echo -machine virt,gic-version=host -cpu host diff --git a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon index d2d2a86139db..e19a444a0684 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon +++ b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon @@ -1,2 +1,5 @@ CONFIG_RCU_TORTURE_TEST=y CONFIG_PRINTK_TIME=y +CONFIG_HYPERVISOR_GUEST=y +CONFIG_PARAVIRT=y +CONFIG_KVM_GUEST=y -- cgit v1.2.3 From 7dedfd4335f7b795d12191d03626212ff71e52aa Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 24 Apr 2019 04:39:10 -0700 Subject: torture: Capture qemu output Currently qemu output appears on standard output, but is inaccessible later on. This commit therefore captures this output and causes kvm-recheck.sh to output this output if QEMU gave a non-zero non-137 exit code. (And exit code of 137 indicates that QEMU was killed, in which case we want to know about the hang rather than the fact that QEMU was killed.) Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/kvm-recheck.sh | 10 +++++++++- tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh | 2 +- 2 files changed, 10 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh index 2297ddc2d4c5..e5edd5198725 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh @@ -30,8 +30,16 @@ do TORTURE_SUITE="`cat $i/../TORTURE_SUITE`" rm -f $i/console.log.*.diags kvm-recheck-${TORTURE_SUITE}.sh $i - if test -f "$i/console.log" + if test -f "$i/qemu-retval" && test "`cat $i/qemu-retval`" -ne 0 && test "`cat $i/qemu-retval`" -ne 137 then + echo QEMU error, output: + cat $i/qemu-output + elif test -f "$i/console.log" + then + if test -f "$i/qemu-retval" && test "`cat $i/qemu-retval`" -eq 137 + then + echo QEMU killed + fi configcheck.sh $i/.config $i/ConfigFragment if test -r $i/Make.oldconfig.err then diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh index 0eb1ec16d78a..003511494fd9 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh @@ -165,7 +165,7 @@ then fi echo "NOTE: $QEMU either did not run or was interactive" > $resdir/console.log echo $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append \"$qemu_append $boot_args\" > $resdir/qemu-cmd -( $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append "$qemu_append $boot_args"& echo $! > $resdir/qemu_pid; wait `cat $resdir/qemu_pid`; echo $? > $resdir/qemu-retval ) & +( $QEMU $qemu_args -m $TORTURE_QEMU_MEM -kernel $KERNEL -append "$qemu_append $boot_args" > $resdir/qemu-output 2>&1 & echo $! > $resdir/qemu_pid; wait `cat $resdir/qemu_pid`; echo $? > $resdir/qemu-retval ) & commandcompleted=0 sleep 10 # Give qemu's pid a chance to reach the file if test -s "$resdir/qemu_pid" -- cgit v1.2.3 From cd6cb7c8a509b1e785fa67e2eb6bd5003198ac39 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 1 May 2019 13:26:11 -0700 Subject: torture: Add function graph-tracing cheat sheet Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/kvm.sh | 2 ++ 1 file changed, 2 insertions(+) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh index 8f1e337b9b54..3b4868906794 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm.sh @@ -464,3 +464,5 @@ else fi # Tracing: trace_event=rcu:rcu_grace_period,rcu:rcu_future_grace_period,rcu:rcu_grace_period_init,rcu:rcu_nocb_wake,rcu:rcu_preempt_task,rcu:rcu_unlock_preempted_task,rcu:rcu_quiescent_state_report,rcu:rcu_fqs,rcu:rcu_callback,rcu:rcu_kfree_callback,rcu:rcu_batch_start,rcu:rcu_invoke_callback,rcu:rcu_invoke_kfree_callback,rcu:rcu_batch_end,rcu:rcu_torture_read,rcu:rcu_barrier +# Function-graph tracing: ftrace=function_graph ftrace_graph_filter=sched_setaffinity,migration_cpu_stop +# Also --kconfig "CONFIG_FUNCTION_TRACER=y CONFIG_FUNCTION_GRAPH_TRACER=y" -- cgit v1.2.3 From 6dc82595ef0839a45c26075612f304979b6c92c2 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 10 May 2019 21:31:52 -0700 Subject: torture: Run kernel build in source directory For historical reasons, rcutorture places its build products in a tools/testing/selftests/rcutorture/b1 directory using the O= kbuild command-line argument. However, doing this requires that the source directory be pristine: Not just "make clean" pristine, but instead "make mrproper" (or, equivalently, "make distclean") pristine. Therefore, rcutorture executes a "make mrproper" before each build. Unfortunately, "make mrproper" has the side effect of removing pretty much everything, including tags files and cscope databases, which can be inconvenient to people whose workflow centers around a single source tree. This commit therefore makes rcutorture do the build directly in the source directory, removing the need for "make mrproper". This works because all needed build products are moved to their proper place in the "res" directory immediately after the build completes, so that multiple rcutorture kernels can still run concurrently. Reported-by: Peter Zijlstra Signed-off-by: Paul E. McKenney --- .../testing/selftests/rcutorture/bin/configinit.sh | 36 ++++++---------------- .../testing/selftests/rcutorture/bin/kvm-build.sh | 9 +++--- .../selftests/rcutorture/bin/kvm-test-1-run.sh | 21 +++++-------- tools/testing/selftests/rcutorture/bin/kvm.sh | 3 +- 4 files changed, 22 insertions(+), 47 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/configinit.sh b/tools/testing/selftests/rcutorture/bin/configinit.sh index 40359486b3a8..bbeae6f67c36 100755 --- a/tools/testing/selftests/rcutorture/bin/configinit.sh +++ b/tools/testing/selftests/rcutorture/bin/configinit.sh @@ -1,7 +1,7 @@ #!/bin/bash # SPDX-License-Identifier: GPL-2.0+ # -# Usage: configinit.sh config-spec-file build-output-dir results-dir +# Usage: configinit.sh config-spec-file results-dir # # Create a .config file from the spec file. Run from the kernel source tree. # Exits with 0 if all went well, with 1 if all went well but the config @@ -11,10 +11,6 @@ # desired settings, for example, "CONFIG_NO_HZ=y". For best results, # this should be a full pathname. # -# The second argument is a optional path to a build output directory, -# for example, "O=/tmp/foo". If this argument is omitted, the .config -# file will be generated directly in the current directory. -# # Copyright (C) IBM Corporation, 2013 # # Authors: Paul E. McKenney @@ -26,34 +22,20 @@ mkdir $T # Capture config spec file. c=$1 -buildloc=$2 -resdir=$3 -builddir= -if echo $buildloc | grep -q '^O=' -then - builddir=`echo $buildloc | sed -e 's/^O=//'` - if test ! -d $builddir - then - mkdir $builddir - fi -else - echo Bad build directory: \"$buildloc\" - exit 2 -fi +resdir=$2 sed -e 's/^\(CONFIG[0-9A-Z_]*\)=.*$/grep -v "^# \1" |/' < $c > $T/u.sh sed -e 's/^\(CONFIG[0-9A-Z_]*=\).*$/grep -v \1 |/' < $c >> $T/u.sh grep '^grep' < $T/u.sh > $T/upd.sh echo "cat - $c" >> $T/upd.sh -make mrproper -make $buildloc distclean > $resdir/Make.distclean 2>&1 -make $buildloc $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1 -mv $builddir/.config $builddir/.config.sav -sh $T/upd.sh < $builddir/.config.sav > $builddir/.config -cp $builddir/.config $builddir/.config.new -yes '' | make $buildloc oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err +make clean > $resdir/Make.clean 2>&1 +make $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1 +mv .config .config.sav +sh $T/upd.sh < .config.sav > .config +cp .config .config.new +yes '' | make oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err # verify new config matches specification. -configcheck.sh $builddir/.config $c +configcheck.sh .config $c exit 0 diff --git a/tools/testing/selftests/rcutorture/bin/kvm-build.sh b/tools/testing/selftests/rcutorture/bin/kvm-build.sh index c27a0bbb9c02..18d6518504ee 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-build.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-build.sh @@ -3,7 +3,7 @@ # # Build a kvm-ready Linux kernel from the tree in the current directory. # -# Usage: kvm-build.sh config-template build-dir resdir +# Usage: kvm-build.sh config-template resdir # # Copyright (C) IBM Corporation, 2011 # @@ -15,8 +15,7 @@ then echo "kvm-build.sh :$config_template: Not a readable file" exit 1 fi -builddir=${2} -resdir=${3} +resdir=${2} T=${TMPDIR-/tmp}/test-linux.sh.$$ trap 'rm -rf $T' 0 @@ -29,14 +28,14 @@ CONFIG_VIRTIO_PCI=y CONFIG_VIRTIO_CONSOLE=y ___EOF___ -configinit.sh $T/config O=$builddir $resdir +configinit.sh $T/config $resdir retval=$? if test $retval -gt 1 then exit 2 fi ncpus=`cpus2use.sh` -make O=$builddir -j$ncpus $TORTURE_KMAKE_ARG > $resdir/Make.out 2>&1 +make -j$ncpus $TORTURE_KMAKE_ARG > $resdir/Make.out 2>&1 retval=$? if test $retval -ne 0 || grep "rcu[^/]*": < $resdir/Make.out | egrep -q "Stop|Error|error:|warning:" || egrep -q "Stop|Error|error:" < $resdir/Make.out then diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh index 003511494fd9..27b7b5693ede 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh @@ -36,11 +36,6 @@ config_template=${1} config_dir=`echo $config_template | sed -e 's,/[^/]*$,,'` title=`echo $config_template | sed -e 's/^.*\///'` builddir=${2} -if test -z "$builddir" -o ! -d "$builddir" -o ! -w "$builddir" -then - echo "kvm-test-1-run.sh :$builddir: Not a writable directory, cannot build into it" - exit 1 -fi resdir=${3} if test -z "$resdir" -o ! -d "$resdir" -o ! -w "$resdir" then @@ -85,18 +80,18 @@ then ln -s $base_resdir/.config $resdir # for kvm-recheck.sh # Arch-independent indicator touch $resdir/builtkernel -elif kvm-build.sh $T/Kc2 $builddir $resdir +elif kvm-build.sh $T/Kc2 $resdir then # Had to build a kernel for this test. - QEMU="`identify_qemu $builddir/vmlinux`" + QEMU="`identify_qemu vmlinux`" BOOT_IMAGE="`identify_boot_image $QEMU`" - cp $builddir/vmlinux $resdir - cp $builddir/.config $resdir - cp $builddir/Module.symvers $resdir > /dev/null || : - cp $builddir/System.map $resdir > /dev/null || : + cp vmlinux $resdir + cp .config $resdir + cp Module.symvers $resdir > /dev/null || : + cp System.map $resdir > /dev/null || : if test -n "$BOOT_IMAGE" then - cp $builddir/$BOOT_IMAGE $resdir + cp $BOOT_IMAGE $resdir KERNEL=$resdir/${BOOT_IMAGE##*/} # Arch-independent indicator touch $resdir/builtkernel @@ -107,7 +102,7 @@ then parse-build.sh $resdir/Make.out $title else # Build failed. - cp $builddir/.config $resdir || : + cp .config $resdir || : echo Build failed, not running KVM, see $resdir. if test -f $builddir.wait then diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh index 3b4868906794..8c43eb43409b 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm.sh @@ -342,7 +342,7 @@ function dump(first, pastlast, batchnum) print "needqemurun=" jn=1 for (j = first; j < pastlast; j++) { - builddir=KVM "/b1" + builddir=KVM "/b" j - first + 1 cpusr[jn] = cpus[j]; if (cfrep[cf[j]] == "") { cfr[jn] = cf[j]; @@ -358,7 +358,6 @@ function dump(first, pastlast, batchnum) print "echo ", cfr[jn], cpusr[jn] ovf ": Starting build. `date` | tee -a " rd "log"; print "rm -f " builddir ".*"; print "touch " builddir ".wait"; - print "mkdir " builddir " > /dev/null 2>&1 || :"; print "mkdir " rd cfr[jn] " || :"; print "kvm-test-1-run.sh " CONFIGDIR cf[j], builddir, rd cfr[jn], dur " \"" TORTURE_QEMU_ARG "\" \"" TORTURE_BOOTARGS "\" > " rd cfr[jn] "/kvm-test-1-run.sh.out 2>&1 &" print "echo ", cfr[jn], cpusr[jn] ovf ": Waiting for build to complete. `date` | tee -a " rd "log"; -- cgit v1.2.3 From 7225c0777271bb489ad6fb095aa10985ad138a81 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 11 May 2019 17:59:52 -0700 Subject: torture: Make --cpus override idleness calculations Currently, rcutorture will use relatively few CPUs to build the kernel on a busy system, which is often as it should be. However, if the user has used the --cpus argument to dedicate a specified number of CPUs to this torture test, it would be good if the kernel build also made use of them. This commit therefore changes the cpus2use.sh script to use --cpus when specified and to do the idleness calculations otherwise. Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/cpus2use.sh | 5 +++++ tools/testing/selftests/rcutorture/bin/kvm.sh | 3 +++ 2 files changed, 8 insertions(+) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/cpus2use.sh b/tools/testing/selftests/rcutorture/bin/cpus2use.sh index ff7102212703..4e9485590c10 100755 --- a/tools/testing/selftests/rcutorture/bin/cpus2use.sh +++ b/tools/testing/selftests/rcutorture/bin/cpus2use.sh @@ -9,6 +9,11 @@ # # Authors: Paul E. McKenney +if test -n "$TORTURE_ALLOTED_CPUS" +then + echo $TORTURE_ALLOTED_CPUS + exit 0 +fi ncpus=`grep '^processor' /proc/cpuinfo | wc -l` idlecpus=`mpstat | tail -1 | \ awk -v ncpus=$ncpus '{ print ncpus * ($7 + $NF) / 100 }'` diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh index 8c43eb43409b..ea6289a335f2 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm.sh @@ -24,6 +24,7 @@ dur=$((30*60)) dryrun="" KVM="`pwd`/tools/testing/selftests/rcutorture"; export KVM PATH=${KVM}/bin:$PATH; export PATH +TORTURE_ALLOTED_CPUS="" TORTURE_DEFCONFIG=defconfig TORTURE_BOOT_IMAGE="" TORTURE_INITRD="$KVM/initrd"; export TORTURE_INITRD @@ -89,6 +90,7 @@ do --cpus) checkarg --cpus "(number)" "$#" "$2" '^[0-9]*$' '^--' cpus=$2 + TORTURE_ALLOTED_CPUS="$2" shift ;; --datestamp) @@ -285,6 +287,7 @@ cat << ___EOF___ > $T/script CONFIGFRAG="$CONFIGFRAG"; export CONFIGFRAG KVM="$KVM"; export KVM PATH="$PATH"; export PATH +TORTURE_ALLOTED_CPUS="$TORTURE_ALLOTED_CPUS"; export TORTURE_ALLOTED_CPUS TORTURE_BOOT_IMAGE="$TORTURE_BOOT_IMAGE"; export TORTURE_BOOT_IMAGE TORTURE_BUILDONLY="$TORTURE_BUILDONLY"; export TORTURE_BUILDONLY TORTURE_DEFCONFIG="$TORTURE_DEFCONFIG"; export TORTURE_DEFCONFIG -- cgit v1.2.3 From b93c765fda30cadae6aafb9d32a30f9391dc0b41 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 11 May 2019 20:18:00 -0700 Subject: torture: Add --trust-make to suppress "make clean" The current rcutorture scripts unconditionally do "make clean", which is a good way of getting the needed testing done despite any imperfections in Makefile dependency tracking. However, this can be a bit irritating when repeatedly running a single scenario after small changes, for example, when debugging a problem that affects only a single scenario. This commit therefore adds a --trust-make argument that suppresses the "make clean". Even when using ccache, this speeds up kernel builds by up to almost an order of magnitude on my laptop. Reported-by: Peter Zijlstra Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/configinit.sh | 5 ++++- tools/testing/selftests/rcutorture/bin/kvm.sh | 6 ++++++ tools/testing/selftests/rcutorture/bin/parse-build.sh | 2 +- 3 files changed, 11 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/configinit.sh b/tools/testing/selftests/rcutorture/bin/configinit.sh index bbeae6f67c36..93e80a42249a 100755 --- a/tools/testing/selftests/rcutorture/bin/configinit.sh +++ b/tools/testing/selftests/rcutorture/bin/configinit.sh @@ -28,7 +28,10 @@ sed -e 's/^\(CONFIG[0-9A-Z_]*\)=.*$/grep -v "^# \1" |/' < $c > $T/u.sh sed -e 's/^\(CONFIG[0-9A-Z_]*=\).*$/grep -v \1 |/' < $c >> $T/u.sh grep '^grep' < $T/u.sh > $T/upd.sh echo "cat - $c" >> $T/upd.sh -make clean > $resdir/Make.clean 2>&1 +if test -z "$TORTURE_TRUST_MAKE" +then + make clean > $resdir/Make.clean 2>&1 +fi make $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1 mv .config .config.sav sh $T/upd.sh < .config.sav > .config diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh index ea6289a335f2..72518580df23 100755 --- a/tools/testing/selftests/rcutorture/bin/kvm.sh +++ b/tools/testing/selftests/rcutorture/bin/kvm.sh @@ -33,6 +33,7 @@ TORTURE_KMAKE_ARG="" TORTURE_QEMU_MEM=512 TORTURE_SHUTDOWN_GRACE=180 TORTURE_SUITE=rcu +TORTURE_TRUST_MAKE="" resdir="" configs="" cpus=0 @@ -63,6 +64,7 @@ usage () { echo " --qemu-cmd qemu-system-..." echo " --results absolute-pathname" echo " --torture rcu" + echo " --trust-make" exit 1 } @@ -175,6 +177,9 @@ do jitter=0 fi ;; + --trust-make) + TORTURE_TRUST_MAKE="y" + ;; *) echo Unknown argument $1 usage @@ -300,6 +305,7 @@ TORTURE_QEMU_MAC="$TORTURE_QEMU_MAC"; export TORTURE_QEMU_MAC TORTURE_QEMU_MEM="$TORTURE_QEMU_MEM"; export TORTURE_QEMU_MEM TORTURE_SHUTDOWN_GRACE="$TORTURE_SHUTDOWN_GRACE"; export TORTURE_SHUTDOWN_GRACE TORTURE_SUITE="$TORTURE_SUITE"; export TORTURE_SUITE +TORTURE_TRUST_MAKE="$TORTURE_TRUST_MAKE"; export TORTURE_TRUST_MAKE if ! test -e $resdir then mkdir -p "$resdir" || : diff --git a/tools/testing/selftests/rcutorture/bin/parse-build.sh b/tools/testing/selftests/rcutorture/bin/parse-build.sh index 0701b3bf6ade..09155c15ea65 100755 --- a/tools/testing/selftests/rcutorture/bin/parse-build.sh +++ b/tools/testing/selftests/rcutorture/bin/parse-build.sh @@ -21,7 +21,7 @@ mkdir $T . functions.sh -if grep -q CC < $F +if grep -q CC < $F || test -n "$TORTURE_TRUST_MAKE" then : else -- cgit v1.2.3 From 8997e6311ed6cb95be34409bc6b4a11c7a84ac35 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 22 May 2019 08:52:18 -0700 Subject: torture: Suppress propagating trace_printk() warning When trace_printk() is used, a message including "BUG" is printed to the console, which fools the rcutorture scripting into believing that the corresponding test scenario failed. This commit therefore filters out this particular instance of "BUG", thus avoiding the false-positive test-failure report. Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/parse-console.sh | 1 + 1 file changed, 1 insertion(+) (limited to 'tools') diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh index 4508373a922f..4bf62d7b1cbc 100755 --- a/tools/testing/selftests/rcutorture/bin/parse-console.sh +++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh @@ -106,6 +106,7 @@ fi | tee -a $file.diags egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|detected stalls on CPUs/tasks:|self-detected stall on CPU|Stall ended before state dump start|\?\?\? Writer stall state|rcu_.*kthread starved for' < $file | grep -v 'ODEBUG: ' | +grep -v 'This means that this is a DEBUG kernel and it is' | grep -v 'Warning: unable to open an initial console' > $T.diags if test -s $T.diags then -- cgit v1.2.3 From 9129b017b54dab09eb69b7269026243156e5188e Mon Sep 17 00:00:00 2001 From: Andrea Parri Date: Mon, 27 May 2019 10:49:57 +0200 Subject: rcu: Don't return a value from rcu_assign_pointer() Quoting Paul [1]: "Given that a quick (and perhaps error-prone) search of the uses of rcu_assign_pointer() in v5.1 didn't find a single use of the return value, let's please instead change the documentation and implementation to eliminate the return value." [1] https://lkml.kernel.org/r/20190523135013.GL28207@linux.ibm.com Signed-off-by: Andrea Parri Cc: "Paul E. McKenney" Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes Cc: rcu@vger.kernel.org Cc: Peter Zijlstra Cc: Will Deacon Cc: Mark Rutland Cc: Matthew Wilcox Cc: Sasha Levin Signed-off-by: Paul E. McKenney --- Documentation/RCU/whatisRCU.txt | 8 ++++---- include/linux/rcupdate.h | 5 ++--- tools/include/linux/rcu.h | 4 ++-- tools/testing/radix-tree/linux/rcupdate.h | 2 +- 4 files changed, 9 insertions(+), 10 deletions(-) (limited to 'tools') diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 981651a8b65d..7e1a8721637a 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -212,7 +212,7 @@ synchronize_rcu() rcu_assign_pointer() - typeof(p) rcu_assign_pointer(p, typeof(p) v); + void rcu_assign_pointer(p, typeof(p) v); Yes, rcu_assign_pointer() -is- implemented as a macro, though it would be cool to be able to declare a function in this manner. @@ -220,9 +220,9 @@ rcu_assign_pointer() The updater uses this function to assign a new value to an RCU-protected pointer, in order to safely communicate the change - in value from the updater to the reader. This function returns - the new value, and also executes any memory-barrier instructions - required for a given CPU architecture. + in value from the updater to the reader. This macro does not + evaluate to an rvalue, but it does execute any memory-barrier + instructions required for a given CPU architecture. Perhaps just as important, it serves to document (1) which pointers are protected by RCU and (2) the point at which a diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index a8ed624da555..0c9b92799abc 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -367,7 +367,7 @@ static inline void rcu_preempt_sleep_check(void) { } * other macros that it invokes. */ #define rcu_assign_pointer(p, v) \ -({ \ +do { \ uintptr_t _r_a_p__v = (uintptr_t)(v); \ rcu_check_sparse(p, __rcu); \ \ @@ -375,8 +375,7 @@ static inline void rcu_preempt_sleep_check(void) { } WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \ else \ smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \ - _r_a_p__v; \ -}) +} while (0) /** * rcu_swap_protected() - swap an RCU and a regular pointer diff --git a/tools/include/linux/rcu.h b/tools/include/linux/rcu.h index 7d02527e5bce..9554d3fa54f3 100644 --- a/tools/include/linux/rcu.h +++ b/tools/include/linux/rcu.h @@ -19,7 +19,7 @@ static inline bool rcu_is_watching(void) return false; } -#define rcu_assign_pointer(p, v) ((p) = (v)) -#define RCU_INIT_POINTER(p, v) p=(v) +#define rcu_assign_pointer(p, v) do { (p) = (v); } while (0) +#define RCU_INIT_POINTER(p, v) do { (p) = (v); } while (0) #endif diff --git a/tools/testing/radix-tree/linux/rcupdate.h b/tools/testing/radix-tree/linux/rcupdate.h index fd280b070fdb..fed468fb0c78 100644 --- a/tools/testing/radix-tree/linux/rcupdate.h +++ b/tools/testing/radix-tree/linux/rcupdate.h @@ -7,6 +7,6 @@ #define rcu_dereference_raw(p) rcu_dereference(p) #define rcu_dereference_protected(p, cond) rcu_dereference(p) #define rcu_dereference_check(p, cond) rcu_dereference(p) -#define RCU_INIT_POINTER(p, v) (p) = (v) +#define RCU_INIT_POINTER(p, v) do { (p) = (v); } while (0) #endif -- cgit v1.2.3 From 46f52b1fe79d2453467b904600ae4759808c4a44 Mon Sep 17 00:00:00 2001 From: Andrea Parri Date: Tue, 19 Feb 2019 23:55:22 +0100 Subject: tools/memory-model: Fix comment in MP+poonceonces.litmus The comment should say "Sometimes" for the result. Signed-off-by: Andrea Parri Cc: Will Deacon Cc: Peter Zijlstra Cc: Boqun Feng Cc: Nicholas Piggin Cc: David Howells Cc: Jade Alglave Cc: Luc Maranget Cc: "Paul E. McKenney" Cc: Akira Yokosawa Cc: Daniel Lustig Acked-by: Alan Stern Signed-off-by: Paul E. McKenney --- tools/memory-model/litmus-tests/MP+poonceonces.litmus | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools') diff --git a/tools/memory-model/litmus-tests/MP+poonceonces.litmus b/tools/memory-model/litmus-tests/MP+poonceonces.litmus index b2b60b84fb9d..172f0145301c 100644 --- a/tools/memory-model/litmus-tests/MP+poonceonces.litmus +++ b/tools/memory-model/litmus-tests/MP+poonceonces.litmus @@ -1,7 +1,7 @@ C MP+poonceonces (* - * Result: Maybe + * Result: Sometimes * * Can the counter-intuitive message-passing outcome be prevented with * no ordering at all? -- cgit v1.2.3 From 37c600a3cc8a6941d77e853ec4e0e33fffa1046b Mon Sep 17 00:00:00 2001 From: Andrea Parri Date: Tue, 19 Feb 2019 23:55:23 +0100 Subject: tools/memory-model: Do not use "herd" to refer to "herd7" Use "herd7" in each such reference. Signed-off-by: Andrea Parri Cc: Will Deacon Cc: Peter Zijlstra Cc: Boqun Feng Cc: Nicholas Piggin Cc: David Howells Cc: Jade Alglave Cc: Luc Maranget Cc: "Paul E. McKenney" Cc: Akira Yokosawa Cc: Daniel Lustig Acked-by: Alan Stern Signed-off-by: Paul E. McKenney --- tools/memory-model/litmus-tests/README | 2 +- tools/memory-model/lock.cat | 2 +- tools/memory-model/scripts/README | 4 ++-- tools/memory-model/scripts/checkalllitmus.sh | 2 +- tools/memory-model/scripts/checklitmus.sh | 2 +- tools/memory-model/scripts/parseargs.sh | 2 +- tools/memory-model/scripts/runlitmushist.sh | 2 +- 7 files changed, 8 insertions(+), 8 deletions(-) (limited to 'tools') diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README index 5ee08f129094..681f9067fa9e 100644 --- a/tools/memory-model/litmus-tests/README +++ b/tools/memory-model/litmus-tests/README @@ -244,7 +244,7 @@ produce the name: Adding the ".litmus" suffix: SB+rfionceonce-poonceonces.litmus The descriptors that describe connections between consecutive accesses -within the cycle through a given litmus test can be provided by the herd +within the cycle through a given litmus test can be provided by the herd7 tool (Rfi, Po, Fre, and so on) or by the linux-kernel.bell file (Once, Release, Acquire, and so on). diff --git a/tools/memory-model/lock.cat b/tools/memory-model/lock.cat index a059d1a6d8a2..6b52f365d73a 100644 --- a/tools/memory-model/lock.cat +++ b/tools/memory-model/lock.cat @@ -11,7 +11,7 @@ include "cross.cat" (* - * The lock-related events generated by herd are as follows: + * The lock-related events generated by herd7 are as follows: * * LKR Lock-Read: the read part of a spin_lock() or successful * spin_trylock() read-modify-write event pair diff --git a/tools/memory-model/scripts/README b/tools/memory-model/scripts/README index 29375a1fbbfa..095c7eb36f9f 100644 --- a/tools/memory-model/scripts/README +++ b/tools/memory-model/scripts/README @@ -22,7 +22,7 @@ checklitmushist.sh Run all litmus tests having .litmus.out files from previous initlitmushist.sh or newlitmushist.sh runs, comparing the - herd output to that of the original runs. + herd7 output to that of the original runs. checklitmus.sh @@ -43,7 +43,7 @@ initlitmushist.sh judgelitmus.sh - Given a .litmus file and its .litmus.out herd output, check the + Given a .litmus file and its .litmus.out herd7 output, check the .litmus.out file against the .litmus file's "Result:" comment to judge whether the test ran correctly. Not normally run manually, provided instead for use by other scripts. diff --git a/tools/memory-model/scripts/checkalllitmus.sh b/tools/memory-model/scripts/checkalllitmus.sh index b35fcd61ecf6..3c0c7fbbd223 100755 --- a/tools/memory-model/scripts/checkalllitmus.sh +++ b/tools/memory-model/scripts/checkalllitmus.sh @@ -1,7 +1,7 @@ #!/bin/sh # SPDX-License-Identifier: GPL-2.0+ # -# Run herd tests on all .litmus files in the litmus-tests directory +# Run herd7 tests on all .litmus files in the litmus-tests directory # and check each file's result against a "Result:" comment within that # litmus test. If the verification result does not match that specified # in the litmus test, this script prints an error message prefixed with diff --git a/tools/memory-model/scripts/checklitmus.sh b/tools/memory-model/scripts/checklitmus.sh index dd08801a30b0..11461ed40b5e 100755 --- a/tools/memory-model/scripts/checklitmus.sh +++ b/tools/memory-model/scripts/checklitmus.sh @@ -1,7 +1,7 @@ #!/bin/sh # SPDX-License-Identifier: GPL-2.0+ # -# Run a herd test and invokes judgelitmus.sh to check the result against +# Run a herd7 test and invokes judgelitmus.sh to check the result against # a "Result:" comment within the litmus test. It also outputs verification # results to a file whose name is that of the specified litmus test, but # with ".out" appended. diff --git a/tools/memory-model/scripts/parseargs.sh b/tools/memory-model/scripts/parseargs.sh index 859e1d581e05..40f52080fdbd 100644 --- a/tools/memory-model/scripts/parseargs.sh +++ b/tools/memory-model/scripts/parseargs.sh @@ -91,7 +91,7 @@ do shift ;; --herdopts|--herdopt) - checkarg --destdir "(herd options)" "$#" "$2" '.*' '^--' + checkarg --destdir "(herd7 options)" "$#" "$2" '.*' '^--' LKMM_HERD_OPTIONS="$2" shift ;; diff --git a/tools/memory-model/scripts/runlitmushist.sh b/tools/memory-model/scripts/runlitmushist.sh index e507f5f933d5..6ed376f495bb 100644 --- a/tools/memory-model/scripts/runlitmushist.sh +++ b/tools/memory-model/scripts/runlitmushist.sh @@ -79,7 +79,7 @@ then echo ' ---' Summary: 1>&2 grep '!!!' $T/*.sh.out 1>&2 nfail="`grep '!!!' $T/*.sh.out | wc -l`" - echo 'Number of failed herd runs (e.g., timeout): ' $nfail 1>&2 + echo 'Number of failed herd7 runs (e.g., timeout): ' $nfail 1>&2 exit 1 else echo All runs completed successfully. 1>&2 -- cgit v1.2.3 From f9de417121001879d92a86960647adb06b5b81bf Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 20 Jun 2019 11:55:36 -0400 Subject: tools/memory-model: Expand definition of barrier Commit 66be4e66a7f4 ("rcu: locking and unlocking need to always be at least barriers") added compiler barriers back into rcu_read_lock() and rcu_read_unlock(). Furthermore, srcu_read_lock() and srcu_read_unlock() have always contained compiler barriers. The Linux Kernel Memory Model ought to know about these barriers. This patch adds them into the memory model. Signed-off-by: Alan Stern Acked-by: Andrea Parri Signed-off-by: Paul E. McKenney --- tools/memory-model/linux-kernel.cat | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'tools') diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index 36d367054811..8b61218c99fd 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -45,7 +45,8 @@ let strong-fence = mb | gp let nonrw-fence = strong-fence | po-rel | acq-po let fence = nonrw-fence | wmb | rmb let barrier = fencerel(Barrier | Rmb | Wmb | Mb | Sync-rcu | Sync-srcu | - Before-atomic | After-atomic | Acquire | Release) | + Before-atomic | After-atomic | Acquire | Release | + Rcu-lock | Rcu-unlock | Srcu-lock | Srcu-unlock) | (po ; [Release]) | ([Acquire] ; po) (**********************************) -- cgit v1.2.3 From 15aa25cbf0ccc4bd63ed6f2a8065decb7f5e6f89 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 20 Jun 2019 11:55:46 -0400 Subject: tools/memory-model: Change definition of rcu-fence The rcu-fence relation in the Linux Kernel Memory Model is not well named. It doesn't act like any other fence relation, in that it does not relate events before a fence to events after that fence. All it does is relate certain RCU events to one another (those that are ordered by the RCU Guarantee); this induces an actual strong-fence-like relation linking events preceding the first RCU event to those following the second. This patch renames rcu-fence, now called rcu-order. It adds a new definition of rcu-fence, something which should have been present all along because it is used in the rb relation. And it modifies the fence and strong-fence relations by making them incorporate the new rcu-fence. As a result of this change, there is no longer any need to define full-fence in the section for detecting data races. It can simply be replaced by the updated strong-fence relation. This change should have no effect on the operation of the memory model. Signed-off-by: Alan Stern Acked-by: Andrea Parri Signed-off-by: Paul E. McKenney --- tools/memory-model/linux-kernel.cat | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) (limited to 'tools') diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index 8b61218c99fd..ca2f4297b4e6 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -122,24 +122,28 @@ let rcu-link = po? ; hb* ; pb* ; prop ; po (* * Any sequence containing at least as many grace periods as RCU read-side - * critical sections (joined by rcu-link) acts as a generalized strong fence. + * critical sections (joined by rcu-link) induces order like a generalized + * inter-CPU strong fence. * Likewise for SRCU grace periods and read-side critical sections, provided * the synchronize_srcu() and srcu_read_[un]lock() calls refer to the same * struct srcu_struct location. *) -let rec rcu-fence = rcu-gp | srcu-gp | +let rec rcu-order = rcu-gp | srcu-gp | (rcu-gp ; rcu-link ; rcu-rscsi) | ((srcu-gp ; rcu-link ; srcu-rscsi) & loc) | (rcu-rscsi ; rcu-link ; rcu-gp) | ((srcu-rscsi ; rcu-link ; srcu-gp) & loc) | - (rcu-gp ; rcu-link ; rcu-fence ; rcu-link ; rcu-rscsi) | - ((srcu-gp ; rcu-link ; rcu-fence ; rcu-link ; srcu-rscsi) & loc) | - (rcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; rcu-gp) | - ((srcu-rscsi ; rcu-link ; rcu-fence ; rcu-link ; srcu-gp) & loc) | - (rcu-fence ; rcu-link ; rcu-fence) + (rcu-gp ; rcu-link ; rcu-order ; rcu-link ; rcu-rscsi) | + ((srcu-gp ; rcu-link ; rcu-order ; rcu-link ; srcu-rscsi) & loc) | + (rcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; rcu-gp) | + ((srcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; srcu-gp) & loc) | + (rcu-order ; rcu-link ; rcu-order) +let rcu-fence = po ; rcu-order ; po? +let fence = fence | rcu-fence +let strong-fence = strong-fence | rcu-fence (* rb orders instructions just as pb does *) -let rb = prop ; po ; rcu-fence ; po? ; hb* ; pb* ; [Marked] +let rb = prop ; rcu-fence ; hb* ; pb* ; [Marked] irreflexive rb as rcu @@ -163,9 +167,8 @@ flag ~empty mixed-accesses as mixed-accesses (* Executes-before and visibility *) let xbstar = (hb | pb | rb)* -let full-fence = strong-fence | (po ; rcu-fence ; po?) let vis = cumul-fence* ; rfe? ; [Marked] ; - ((full-fence ; [Marked] ; xbstar) | (xbstar & int)) + ((strong-fence ; [Marked] ; xbstar) | (xbstar & int)) (* Boundaries for lifetimes of plain accesses *) let w-pre-bounded = [Marked] ; (addr | fence)? -- cgit v1.2.3 From 4289ee7d5a8343eaddd0986f8fb492868e2f546f Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 20 Jun 2019 11:55:58 -0400 Subject: tools/memory-model: Improve data-race detection Herbert Xu recently reported a problem concerning RCU and compiler barriers. In the course of discussing the problem, he put forth a litmus test which illustrated a serious defect in the Linux Kernel Memory Model's data-race-detection code [1]. The defect was that the LKMM assumed visibility and executes-before ordering of plain accesses had to be mediated by marked accesses. In Herbert's litmus test this wasn't so, and the LKMM claimed the litmus test was allowed and contained a data race although neither is true. In fact, plain accesses can be ordered by fences even in the absence of marked accesses. In most cases this doesn't matter, because most fences only order accesses within a single thread. But the rcu-fence relation is different; it can order (and induce visibility between) accesses in different threads -- events which otherwise might be concurrent. This makes it relevant to data-race detection. This patch makes two changes to the memory model to incorporate the new insight: If a store is separated by a fence from another access, the store is necessarily visible to the other access (as reflected in the ww-vis and wr-vis relations). Similarly, if a load is separated by a fence from another access then the load necessarily executes before the other access (as reflected in the rw-xbstar relation). If a store is separated by a strong fence from a marked access then it is necessarily visible to any access that executes after the marked access (as reflected in the ww-vis and wr-vis relations). With these changes, the LKMM gives the desired result for Herbert's litmus test and other related ones [2]. [1] https://lore.kernel.org/lkml/Pine.LNX.4.44L0.1906041026570.1731-100000@iolanthe.rowland.org/ [2] https://github.com/paulmckrcu/litmus/blob/master/manual/plain/C-S-rcunoderef-1.litmus https://github.com/paulmckrcu/litmus/blob/master/manual/plain/C-S-rcunoderef-2.litmus https://github.com/paulmckrcu/litmus/blob/master/manual/plain/C-S-rcunoderef-3.litmus https://github.com/paulmckrcu/litmus/blob/master/manual/plain/C-S-rcunoderef-4.litmus https://github.com/paulmckrcu/litmus/blob/master/manual/plain/strong-vis.litmus Reported-by: Herbert Xu Signed-off-by: Alan Stern Acked-by: Andrea Parri Signed-off-by: Paul E. McKenney Tested-by: Akira Yokosawa --- tools/memory-model/linux-kernel.cat | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'tools') diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat index ca2f4297b4e6..ea2ff4b94074 100644 --- a/tools/memory-model/linux-kernel.cat +++ b/tools/memory-model/linux-kernel.cat @@ -179,9 +179,11 @@ let r-post-bounded = (nonrw-fence | ([~Noreturn] ; fencerel(Rmb) ; [R4rmb]))? ; [Marked] (* Visibility and executes-before for plain accesses *) -let ww-vis = w-post-bounded ; vis ; w-pre-bounded -let wr-vis = w-post-bounded ; vis ; r-pre-bounded -let rw-xbstar = r-post-bounded ; xbstar ; w-pre-bounded +let ww-vis = fence | (strong-fence ; xbstar ; w-pre-bounded) | + (w-post-bounded ; vis ; w-pre-bounded) +let wr-vis = fence | (strong-fence ; xbstar ; r-pre-bounded) | + (w-post-bounded ; vis ; r-pre-bounded) +let rw-xbstar = fence | (r-post-bounded ; xbstar ; w-pre-bounded) (* Potential races *) let pre-race = ext & ((Plain * M) | ((M \ IW) * Plain)) -- cgit v1.2.3