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graph-lock: remove AioContext locking

Browse source 
Stop acquiring/releasing the AioContext lock in
bdrv_graph_wrlock()/bdrv_graph_unlock() since the lock no longer has any
effect.

The distinction between bdrv_graph_wrunlock() and
bdrv_graph_wrunlock_ctx() becomes meaningless and they can be collapsed
into one function.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231205182011.1976568-6-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2023-12-05 13:20:02 -05:00 • committed by Kevin Wolf
parent b5f4fda4fb
commit 6bc30f1949
20 changed files with 133 additions and 193 deletions
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44
block/graph-lock.c
View file

@ -106,27 +106,12 @@ static uint32_t reader_count(void)
return rd;
}
void no_coroutine_fn bdrv_graph_wrlock(BlockDriverState *bs)
void no_coroutine_fn bdrv_graph_wrlock(void)
{
AioContext *ctx = NULL;
GLOBAL_STATE_CODE();
assert(!qatomic_read(&has_writer));
assert(!qemu_in_coroutine());
/*
* Release only non-mainloop AioContext. The mainloop often relies on the
* BQL and doesn't lock the main AioContext before doing things.
*/
if (bs) {
ctx = bdrv_get_aio_context(bs);
if (ctx != qemu_get_aio_context()) {
aio_context_release(ctx);
} else {
ctx = NULL;
}
}
/* Make sure that constantly arriving new I/O doesn't cause starvation */
bdrv_drain_all_begin_nopoll();
@ -155,27 +140,13 @@ void no_coroutine_fn bdrv_graph_wrlock(BlockDriverState *bs)
} while (reader_count() >= 1);
bdrv_drain_all_end();
if (ctx) {
aio_context_acquire(bdrv_get_aio_context(bs));
}
}
void no_coroutine_fn bdrv_graph_wrunlock_ctx(AioContext *ctx)
void no_coroutine_fn bdrv_graph_wrunlock(void)
{
GLOBAL_STATE_CODE();
assert(qatomic_read(&has_writer));
/*
* Release only non-mainloop AioContext. The mainloop often relies on the
* BQL and doesn't lock the main AioContext before doing things.
*/
if (ctx && ctx != qemu_get_aio_context()) {
aio_context_release(ctx);
} else {
ctx = NULL;
}
WITH_QEMU_LOCK_GUARD(&aio_context_list_lock) {
/*
* No need for memory barriers, this works in pair with
@ -197,17 +168,6 @@ void no_coroutine_fn bdrv_graph_wrunlock_ctx(AioContext *ctx)
* progress.
*/
aio_bh_poll(qemu_get_aio_context());
if (ctx) {
aio_context_acquire(ctx);
}
}
void no_coroutine_fn bdrv_graph_wrunlock(BlockDriverState *bs)
{
AioContext *ctx = bs ? bdrv_get_aio_context(bs) : NULL;
bdrv_graph_wrunlock_ctx(ctx);
}
void coroutine_fn bdrv_graph_co_rdlock(void)