Commit 37198768 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware) Committed by Linus Torvalds

sbitmap: Protect swap_lock from softirqs

The swap_lock used by sbitmap has a chain with locks taken from softirq,
but the swap_lock is not protected from being preempted by softirqs.

A chain exists of:

 sbq->ws[i].wait -> dispatch_wait_lock -> swap_lock

Where the sbq->ws[i].wait lock can be taken from softirq context, which
means all locks below it in the chain must also be protected from
softirqs.
Reported-by: default avatarClark Williams <williams@redhat.com>
Fixes: 58ab5e32 ("sbitmap: silence bogus lockdep IRQ warning")
Fixes: ea86ea2c ("sbitmap: amortize cost of clearing bits")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c962cb32
......@@ -26,14 +26,9 @@
static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index)
{
unsigned long mask, val;
unsigned long __maybe_unused flags;
bool ret = false;
/* Silence bogus lockdep warning */
#if defined(CONFIG_LOCKDEP)
local_irq_save(flags);
#endif
spin_lock(&sb->map[index].swap_lock);
spin_lock_bh(&sb->map[index].swap_lock);
if (!sb->map[index].cleared)
goto out_unlock;
......@@ -54,10 +49,7 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index)
ret = true;
out_unlock:
spin_unlock(&sb->map[index].swap_lock);
#if defined(CONFIG_LOCKDEP)
local_irq_restore(flags);
#endif
spin_unlock_bh(&sb->map[index].swap_lock);
return ret;
}
......
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