snowball/igloo-kernel.git/kernel, branch v2.6.38.2

perf: Fix tear-down of inherited group events

2011-03-27T18:36:35+00:00

commit 38b435b16c36b0d863efcf3f07b34a6fac9873fd upstream. When destroying inherited events, we need to destroy groups too, otherwise the event iteration in perf_event_exit_task_context() will miss group siblings and we leak events with all the consequences. Reported-and-tested-by: Vince Weaver Signed-off-by: Peter Zijlstra LKML-Reference: <1300196470.2203.61.camel@twins> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

sysctl: restrict write access to dmesg_restrict

2011-03-27T18:36:01+00:00

commit bfdc0b497faa82a0ba2f9dddcf109231dd519fcc upstream. When dmesg_restrict is set to 1 CAP_SYS_ADMIN is needed to read the kernel ring buffer. But a root user without CAP_SYS_ADMIN is able to reset dmesg_restrict to 0. This is an issue when e.g. LXC (Linux Containers) are used and complete user space is running without CAP_SYS_ADMIN. A unprivileged and jailed root user can bypass the dmesg_restrict protection. With this patch writing to dmesg_restrict is only allowed when root has CAP_SYS_ADMIN. Signed-off-by: Richard Weinberger Acked-by: Dan Rosenberg Acked-by: Serge E. Hallyn Cc: Eric Paris Cc: Kees Cook Cc: James Morris Cc: Eugene Teo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code

2011-03-27T18:35:55+00:00

commit da48524eb20662618854bb3df2db01fc65f3070c upstream. Userland should be able to trust the pid and uid of the sender of a signal if the si_code is SI_TKILL. Unfortunately, the kernel has historically allowed sigqueueinfo() to send any si_code at all (as long as it was negative - to distinguish it from kernel-generated signals like SIGILL etc), so it could spoof a SI_TKILL with incorrect siginfo values. Happily, it looks like glibc has always set si_code to the appropriate SI_QUEUE, so there are probably no actual user code that ever uses anything but the appropriate SI_QUEUE flag. So just tighten the check for si_code (we used to allow any negative value), and add a (one-time) warning in case there are binaries out there that might depend on using other si_code values. Signed-off-by: Julien Tinnes Acked-by: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

cgroups: if you list_empty() a head then don't list_del() it

2011-03-27T18:35:43+00:00

commit 8d2587970b8bdf7c8d9208e3f4bb93182aef1a0f upstream. list_del() leaves poison in the prev and next pointers. The next list_empty() will compare those poisons, and say the list isn't empty. Any list operations that assume the node is on a list because of such a check will be fooled into dereferencing poison. One needs to INIT the node after the del, and fortunately there's already a wrapper for that - list_del_init(). Some of the dels are followed by deallocations, so can be ignored, and one can be merged with an add to make a move. Apart from that, I erred on the side of caution in making nodes list_empty()-queriable. Signed-off-by: Phil Carmody Reviewed-by: Paul Menage Cc: Li Zefan Acked-by: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

smp_call_function_many: handle concurrent clearing of mask

2011-03-23T20:04:08+00:00

commit 723aae25d5cdb09962901d36d526b44d4be1051c upstream. Mike Galbraith reported finding a lockup ("perma-spin bug") where the cpumask passed to smp_call_function_many was cleared by other cpu(s) while a cpu was preparing its call_data block, resulting in no cpu to clear the last ref and unlock the block. Having cpus clear their bit asynchronously could be useful on a mask of cpus that might have a translation context, or cpus that need a push to complete an rcu window. Instead of adding a BUG_ON and requiring yet another cpumask copy, just detect the race and handle it. Note: arch_send_call_function_ipi_mask must still handle an empty cpumask because the data block is globally visible before the that arch callback is made. And (obviously) there are no guarantees to which cpus are notified if the mask is changed during the call; only cpus that were online and had their mask bit set during the whole call are guaranteed to be called. Reported-by: Mike Galbraith Reported-by: Jan Beulich Acked-by: Jan Beulich Signed-off-by: Milton Miller Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

call_function_many: add missing ordering

2011-03-23T20:04:07+00:00

commit 45a5791920ae643eafc02e2eedef1a58e341b736 upstream. Paul McKenney's review pointed out two problems with the barriers in the 2.6.38 update to the smp call function many code. First, a barrier that would force the func and info members of data to be visible before their consumption in the interrupt handler was missing. This can be solved by adding a smp_wmb between setting the func and info members and setting setting the cpumask; this will pair with the existing and required smp_rmb ordering the cpumask read before the read of refs. This placement avoids the need a second smp_rmb in the interrupt handler which would be executed on each of the N cpus executing the call request. (I was thinking this barrier was present but was not). Second, the previous write to refs (establishing the zero that we the interrupt handler was testing from all cpus) was performed by a third party cpu. This would invoke transitivity which, as a recient or concurrent addition to memory-barriers.txt now explicitly states, would require a full smp_mb(). However, we know the cpumask will only be set by one cpu (the data owner) and any preivous iteration of the mask would have cleared by the reading cpu. By redundantly writing refs to 0 on the owning cpu before the smp_wmb, the write to refs will follow the same path as the writes that set the cpumask, which in turn allows us to keep the barrier in the interrupt handler a smp_rmb instead of promoting it to a smp_mb (which will be be executed by N cpus for each of the possible M elements on the list). I moved and expanded the comment about our (ab)use of the rcu list primitives for the concurrent walk earlier into this function. I considered moving the first two paragraphs to the queue list head and lock, but felt it would have been too disconected from the code. Cc: Paul McKinney Signed-off-by: Milton Miller Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

call_function_many: fix list delete vs add race

2011-03-23T20:04:07+00:00

commit e6cd1e07a185d5f9b0aa75e020df02d3c1c44940 upstream. Peter pointed out there was nothing preventing the list_del_rcu in smp_call_function_interrupt from running before the list_add_rcu in smp_call_function_many. Fix this by not setting refs until we have gotten the lock for the list. Take advantage of the wmb in list_add_rcu to save an explicit additional one. I tried to force this race with a udelay before the lock & list_add and by mixing all 64 online cpus with just 3 random cpus in the mask, but was unsuccessful. Still, inspection shows a valid race, and the fix is a extension of the existing protection window in the current code. Reported-by: Peter Zijlstra Signed-off-by: Milton Miller Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

perf: Handle stopped state with tracepoints

2011-03-23T20:04:05+00:00

commit a0f7d0f7fc02465bb9758501f611f63381792996 upstream. We toggle the state from start and stop callbacks but actually don't check it when the event triggers. Do it so that these callbacks actually work. Signed-off-by: Frederic Weisbecker Cc: Arnaldo Carvalho de Melo Cc: Paul Mackerras Cc: Stephane Eranian Signed-off-by: Peter Zijlstra LKML-Reference: <1299529629-18280-2-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

perf: Fix the software events state check

2011-03-23T20:04:04+00:00

commit 91b2f482e62ad0d444222253026a5cbca28c4ab9 upstream. Fix the mistakenly inverted check of events state. Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Paul Mackerras Cc: Stephane Eranian LKML-Reference: <1299529629-18280-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

ftrace: Fix memory leak with function graph and cpu hotplug

2011-03-23T20:03:32+00:00

commit 868baf07b1a259f5f3803c1dc2777b6c358f83cf upstream. When the fuction graph tracer starts, it needs to make a special stack for each task to save the real return values of the tasks. All running tasks have this stack created, as well as any new tasks. On CPU hot plug, the new idle task will allocate a stack as well when init_idle() is called. The problem is that cpu hotplug does not create a new idle_task. Instead it uses the idle task that existed when the cpu went down. ftrace_graph_init_task() will add a new ret_stack to the task that is given to it. Because a clone will make the task have a stack of its parent it does not check if the task's ret_stack is already NULL or not. When the CPU hotplug code starts a CPU up again, it will allocate a new stack even though one already existed for it. The solution is to treat the idle_task specially. In fact, the function_graph code already does, just not at init_idle(). Instead of using the ftrace_graph_init_task() for the idle task, which that function expects the task to be a clone, have a separate ftrace_graph_init_idle_task(). Also, we will create a per_cpu ret_stack that is used by the idle task. When we call ftrace_graph_init_idle_task() it will check if the idle task's ret_stack is NULL, if it is, then it will assign it the per_cpu ret_stack. Reported-by: Benjamin Herrenschmidt Suggested-by: Peter Zijlstra Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman