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async: remove unnecessary inc/dec pairs

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Pull the increment/decrement pair out of aio_bh_poll and into the
callers.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-18-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini
2017-02-13 14:52:34 +01:00
committed by Stefan Hajnoczi
parent a153bf52b3
commit bd451435c0
3 changed files with 13 additions and 15 deletions
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12
util/async.c
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@ -90,15 +90,16 @@ void aio_bh_call(QEMUBH *bh)
bh->cb(bh->opaque);
}
/* Multiple occurrences of aio_bh_poll cannot be called concurrently */
/* Multiple occurrences of aio_bh_poll cannot be called concurrently.
* The count in ctx->list_lock is incremented before the call, and is
* not affected by the call.
*/
int aio_bh_poll(AioContext *ctx)
{
QEMUBH *bh, **bhp, *next;
int ret;
bool deleted = false;
qemu_lockcnt_inc(&ctx->list_lock);
ret = 0;
for (bh = atomic_rcu_read(&ctx->first_bh); bh; bh = next) {
next = atomic_rcu_read(&bh->next);
@ -123,11 +124,10 @@ int aio_bh_poll(AioContext *ctx)
/* remove deleted bhs */
if (!deleted) {
qemu_lockcnt_dec(&ctx->list_lock);
return ret;
}
if (qemu_lockcnt_dec_and_lock(&ctx->list_lock)) {
if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
bhp = &ctx->first_bh;
while (*bhp) {
bh = *bhp;
@ -138,7 +138,7 @@ int aio_bh_poll(AioContext *ctx)
bhp = &bh->next;
}
}
qemu_lockcnt_unlock(&ctx->list_lock);
qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
}
return ret;
}