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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-21 01:02:14 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-21 01:02:14 (GMT) |
commit | 8d99641f6c1af806cd5d9e6badce91910219a161 (patch) | |
tree | ee841f807005a4a6234f6f502a13185d13a34870 /kernel | |
parent | fc887b15d935ead2a00aef5779a18034e7c69ee1 (diff) | |
parent | 225c8e010f2d17a62aef131e24c6e7c111f36f9b (diff) | |
download | linux-fsl-qoriq-8d99641f6c1af806cd5d9e6badce91910219a161.tar.xz |
Merge branch 'akpm'
* akpm:
kernel/smp.c: consolidate writes in smp_call_function_interrupt()
kernel/smp.c: fix smp_call_function_many() SMP race
memcg: correctly order reading PCG_USED and pc->mem_cgroup
backlight: fix 88pm860x_bl macro collision
drivers/leds/ledtrig-gpio.c: make output match input, tighten input checking
MAINTAINERS: update Atmel AT91 entry
mm: fix truncate_setsize() comment
memcg: fix rmdir, force_empty with THP
memcg: fix LRU accounting with THP
memcg: fix USED bit handling at uncharge in THP
memcg: modify accounting function for supporting THP better
fs/direct-io.c: don't try to allocate more than BIO_MAX_PAGES in a bio
mm: compaction: prevent division-by-zero during user-requested compaction
mm/vmscan.c: remove duplicate include of compaction.h
memblock: fix memblock_is_region_memory()
thp: keep highpte mapped until it is no longer needed
kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/smp.c | 51 |
1 files changed, 45 insertions, 6 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index 4ec30e0..2fe66f7 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -194,23 +194,52 @@ void generic_smp_call_function_interrupt(void) */ list_for_each_entry_rcu(data, &call_function.queue, csd.list) { int refs; + void (*func) (void *info); - if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) + /* + * Since we walk the list without any locks, we might + * see an entry that was completed, removed from the + * list and is in the process of being reused. + * + * We must check that the cpu is in the cpumask before + * checking the refs, and both must be set before + * executing the callback on this cpu. + */ + + if (!cpumask_test_cpu(cpu, data->cpumask)) continue; + smp_rmb(); + + if (atomic_read(&data->refs) == 0) + continue; + + func = data->csd.func; /* for later warn */ data->csd.func(data->csd.info); + /* + * If the cpu mask is not still set then it enabled interrupts, + * we took another smp interrupt, and executed the function + * twice on this cpu. In theory that copy decremented refs. + */ + if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) { + WARN(1, "%pS enabled interrupts and double executed\n", + func); + continue; + } + refs = atomic_dec_return(&data->refs); WARN_ON(refs < 0); - if (!refs) { - raw_spin_lock(&call_function.lock); - list_del_rcu(&data->csd.list); - raw_spin_unlock(&call_function.lock); - } if (refs) continue; + WARN_ON(!cpumask_empty(data->cpumask)); + + raw_spin_lock(&call_function.lock); + list_del_rcu(&data->csd.list); + raw_spin_unlock(&call_function.lock); + csd_unlock(&data->csd); } @@ -454,11 +483,21 @@ void smp_call_function_many(const struct cpumask *mask, data = &__get_cpu_var(cfd_data); csd_lock(&data->csd); + BUG_ON(atomic_read(&data->refs) || !cpumask_empty(data->cpumask)); data->csd.func = func; data->csd.info = info; cpumask_and(data->cpumask, mask, cpu_online_mask); cpumask_clear_cpu(this_cpu, data->cpumask); + + /* + * To ensure the interrupt handler gets an complete view + * we order the cpumask and refs writes and order the read + * of them in the interrupt handler. In addition we may + * only clear our own cpu bit from the mask. + */ + smp_wmb(); + atomic_set(&data->refs, cpumask_weight(data->cpumask)); raw_spin_lock_irqsave(&call_function.lock, flags); |