From: Peter Zijlstra Date: Mon, 6 Nov 2006 07:52:10 +0000 (-0800) Subject: [PATCH] lockdep: fix delayacct locking bug X-Git-Tag: MMI-PSA29.97-13-9~45515^2~20^2~193 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=64efade11cddc4237c1b95ea4ca18af122a7e19e;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git [PATCH] lockdep: fix delayacct locking bug Make the delayacct lock irqsave; this avoids the possible deadlock where an interrupt is taken while holding the delayacct lock which needs to take the delayacct lock. Signed-off-by: Peter Zijlstra Acked-by: Oleg Nesterov Cc: Balbir Singh Cc: Shailabh Nagar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/delayacct.c b/kernel/delayacct.c index 36752f124c6a..66a0ea48751d 100644 --- a/kernel/delayacct.c +++ b/kernel/delayacct.c @@ -66,6 +66,7 @@ static void delayacct_end(struct timespec *start, struct timespec *end, { struct timespec ts; s64 ns; + unsigned long flags; do_posix_clock_monotonic_gettime(end); ts = timespec_sub(*end, *start); @@ -73,10 +74,10 @@ static void delayacct_end(struct timespec *start, struct timespec *end, if (ns < 0) return; - spin_lock(¤t->delays->lock); + spin_lock_irqsave(¤t->delays->lock, flags); *total += ns; (*count)++; - spin_unlock(¤t->delays->lock); + spin_unlock_irqrestore(¤t->delays->lock, flags); } void __delayacct_blkio_start(void) @@ -104,6 +105,7 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) s64 tmp; struct timespec ts; unsigned long t1,t2,t3; + unsigned long flags; /* Though tsk->delays accessed later, early exit avoids * unnecessary returning of other data @@ -136,14 +138,14 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) /* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ - spin_lock(&tsk->delays->lock); + spin_lock_irqsave(&tsk->delays->lock, flags); tmp = d->blkio_delay_total + tsk->delays->blkio_delay; d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp; tmp = d->swapin_delay_total + tsk->delays->swapin_delay; d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp; d->blkio_count += tsk->delays->blkio_count; d->swapin_count += tsk->delays->swapin_count; - spin_unlock(&tsk->delays->lock); + spin_unlock_irqrestore(&tsk->delays->lock, flags); done: return 0; @@ -152,11 +154,12 @@ done: __u64 __delayacct_blkio_ticks(struct task_struct *tsk) { __u64 ret; + unsigned long flags; - spin_lock(&tsk->delays->lock); + spin_lock_irqsave(&tsk->delays->lock, flags); ret = nsec_to_clock_t(tsk->delays->blkio_delay + tsk->delays->swapin_delay); - spin_unlock(&tsk->delays->lock); + spin_unlock_irqrestore(&tsk->delays->lock, flags); return ret; }