diff options
| -rw-r--r-- | kernel/rcu/tree.c | 71 | ||||
| -rw-r--r-- | kernel/rcu/tree.h | 4 |
2 files changed, 37 insertions, 38 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a4c25a6283b0..73a4c9d07b86 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -91,7 +91,7 @@ static struct rcu_state rcu_state = { .abbr = RCU_ABBR, .exp_mutex = __MUTEX_INITIALIZER(rcu_state.exp_mutex), .exp_wake_mutex = __MUTEX_INITIALIZER(rcu_state.exp_wake_mutex), - .ofl_lock = __RAW_SPIN_LOCK_UNLOCKED(rcu_state.ofl_lock), + .ofl_lock = __ARCH_SPIN_LOCK_UNLOCKED, }; /* Dump rcu_node combining tree at boot to verify correct setup. */ @@ -1175,7 +1175,15 @@ bool rcu_lockdep_current_cpu_online(void) preempt_disable_notrace(); rdp = this_cpu_ptr(&rcu_data); rnp = rdp->mynode; - if (rdp->grpmask & rcu_rnp_online_cpus(rnp) || READ_ONCE(rnp->ofl_seq) & 0x1) + /* + * Strictly, we care here about the case where the current CPU is + * in rcu_cpu_starting() and thus has an excuse for rdp->grpmask + * not being up to date. So arch_spin_is_locked() might have a + * false positive if it's held by some *other* CPU, but that's + * OK because that just means a false *negative* on the warning. + */ + if (rdp->grpmask & rcu_rnp_online_cpus(rnp) || + arch_spin_is_locked(&rcu_state.ofl_lock)) ret = true; preempt_enable_notrace(); return ret; @@ -1739,7 +1747,6 @@ static void rcu_strict_gp_boundary(void *unused) */ static noinline_for_stack bool rcu_gp_init(void) { - unsigned long firstseq; unsigned long flags; unsigned long oldmask; unsigned long mask; @@ -1782,22 +1789,17 @@ static noinline_for_stack bool rcu_gp_init(void) * of RCU's Requirements documentation. */ WRITE_ONCE(rcu_state.gp_state, RCU_GP_ONOFF); + /* Exclude CPU hotplug operations. */ rcu_for_each_leaf_node(rnp) { - // Wait for CPU-hotplug operations that might have - // started before this grace period did. - smp_mb(); // Pair with barriers used when updating ->ofl_seq to odd values. - firstseq = READ_ONCE(rnp->ofl_seq); - if (firstseq & 0x1) - while (firstseq == READ_ONCE(rnp->ofl_seq)) - schedule_timeout_idle(1); // Can't wake unless RCU is watching. - smp_mb(); // Pair with barriers used when updating ->ofl_seq to even values. - raw_spin_lock(&rcu_state.ofl_lock); - raw_spin_lock_irq_rcu_node(rnp); + local_irq_save(flags); + arch_spin_lock(&rcu_state.ofl_lock); + raw_spin_lock_rcu_node(rnp); if (rnp->qsmaskinit == rnp->qsmaskinitnext && !rnp->wait_blkd_tasks) { /* Nothing to do on this leaf rcu_node structure. */ - raw_spin_unlock_irq_rcu_node(rnp); - raw_spin_unlock(&rcu_state.ofl_lock); + raw_spin_unlock_rcu_node(rnp); + arch_spin_unlock(&rcu_state.ofl_lock); + local_irq_restore(flags); continue; } @@ -1832,8 +1834,9 @@ static noinline_for_stack bool rcu_gp_init(void) rcu_cleanup_dead_rnp(rnp); } - raw_spin_unlock_irq_rcu_node(rnp); - raw_spin_unlock(&rcu_state.ofl_lock); + raw_spin_unlock_rcu_node(rnp); + arch_spin_unlock(&rcu_state.ofl_lock); + local_irq_restore(flags); } rcu_gp_slow(gp_preinit_delay); /* Races with CPU hotplug. */ @@ -4287,11 +4290,10 @@ void rcu_cpu_starting(unsigned int cpu) rnp = rdp->mynode; mask = rdp->grpmask; - WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1); - WARN_ON_ONCE(!(rnp->ofl_seq & 0x1)); + local_irq_save(flags); + arch_spin_lock(&rcu_state.ofl_lock); rcu_dynticks_eqs_online(); - smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier(). - raw_spin_lock_irqsave_rcu_node(rnp, flags); + raw_spin_lock_rcu_node(rnp); WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext | mask); newcpu = !(rnp->expmaskinitnext & mask); rnp->expmaskinitnext |= mask; @@ -4304,15 +4306,18 @@ void rcu_cpu_starting(unsigned int cpu) /* An incoming CPU should never be blocking a grace period. */ if (WARN_ON_ONCE(rnp->qsmask & mask)) { /* RCU waiting on incoming CPU? */ + /* rcu_report_qs_rnp() *really* wants some flags to restore */ + unsigned long flags2; + + local_irq_save(flags2); rcu_disable_urgency_upon_qs(rdp); /* Report QS -after- changing ->qsmaskinitnext! */ - rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags); + rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags2); } else { - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + raw_spin_unlock_rcu_node(rnp); } - smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier(). - WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1); - WARN_ON_ONCE(rnp->ofl_seq & 0x1); + arch_spin_unlock(&rcu_state.ofl_lock); + local_irq_restore(flags); smp_mb(); /* Ensure RCU read-side usage follows above initialization. */ } @@ -4326,7 +4331,7 @@ void rcu_cpu_starting(unsigned int cpu) */ void rcu_report_dead(unsigned int cpu) { - unsigned long flags; + unsigned long flags, seq_flags; unsigned long mask; struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */ @@ -4340,10 +4345,8 @@ void rcu_report_dead(unsigned int cpu) /* Remove outgoing CPU from mask in the leaf rcu_node structure. */ mask = rdp->grpmask; - WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1); - WARN_ON_ONCE(!(rnp->ofl_seq & 0x1)); - smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier(). - raw_spin_lock(&rcu_state.ofl_lock); + local_irq_save(seq_flags); + arch_spin_lock(&rcu_state.ofl_lock); raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */ rdp->rcu_ofl_gp_seq = READ_ONCE(rcu_state.gp_seq); rdp->rcu_ofl_gp_flags = READ_ONCE(rcu_state.gp_flags); @@ -4354,10 +4357,8 @@ void rcu_report_dead(unsigned int cpu) } WRITE_ONCE(rnp->qsmaskinitnext, rnp->qsmaskinitnext & ~mask); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - raw_spin_unlock(&rcu_state.ofl_lock); - smp_mb(); // Pair with rcu_gp_cleanup()'s ->ofl_seq barrier(). - WRITE_ONCE(rnp->ofl_seq, rnp->ofl_seq + 1); - WARN_ON_ONCE(rnp->ofl_seq & 0x1); + arch_spin_unlock(&rcu_state.ofl_lock); + local_irq_restore(seq_flags); rdp->cpu_started = false; } diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 486fc901bd08..4b4bcef8a974 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -56,8 +56,6 @@ struct rcu_node { /* Initialized from ->qsmaskinitnext at the */ /* beginning of each grace period. */ unsigned long qsmaskinitnext; - unsigned long ofl_seq; /* CPU-hotplug operation sequence count. */ - /* Online CPUs for next grace period. */ unsigned long expmask; /* CPUs or groups that need to check in */ /* to allow the current expedited GP */ /* to complete. */ @@ -355,7 +353,7 @@ struct rcu_state { const char *name; /* Name of structure. */ char abbr; /* Abbreviated name. */ - raw_spinlock_t ofl_lock ____cacheline_internodealigned_in_smp; + arch_spinlock_t ofl_lock ____cacheline_internodealigned_in_smp; /* Synchronize offline with */ /* GP pre-initialization. */ }; |