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aio: free AioContext when aio_context_new() fails

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g_source_destroy() only removes the GSource from the GMainContext it's
attached to, if any. It does not free it.

Use g_source_unref() instead so that the AioContext (which embeds a
GSource) is freed. There is no need to call g_source_destroy() in
aio_context_new() because the GSource isn't attached to a GMainContext
yet.

aio_ctx_finalize() expects everything to be set up already, so introduce
the new ctx->initialized boolean and do nothing when called with
!initialized. This also requires moving aio_context_setup() down after
event_notifier_init() since aio_ctx_finalize() won't release any
resources that aio_context_setup() acquired.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20251104022933.618123-9-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2025-11-03 21:29:26 -05:00 • committed by Kevin Wolf
parent d1f42b600a
commit 3769b9abe9
2 changed files with 31 additions and 3 deletions
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3
include/block/aio.h
View file

@ -291,6 +291,9 @@ struct AioContext {
void *epollfd_tag;
const FDMonOps *fdmon_ops;
/* Was aio_context_new() successful? */
bool initialized;
};
/**

31
util/async.c
View file

@ -366,12 +366,16 @@ aio_ctx_dispatch(GSource *source,
}
static void
aio_ctx_finalize(GSource *source)
aio_ctx_finalize(GSource *source)
{
AioContext *ctx = (AioContext *) source;
QEMUBH *bh;
unsigned flags;
if (!ctx->initialized) {
return;
}
thread_pool_free_aio(ctx->thread_pool);
#ifdef CONFIG_LINUX_AIO
@ -580,16 +584,35 @@ AioContext *aio_context_new(Error **errp)
int ret;
AioContext *ctx;
/*
* ctx is freed by g_source_unref() (e.g. aio_context_unref()). ctx's
* resources are freed as follows:
*
* 1. By aio_ctx_finalize() after aio_context_new() has returned and set
* ->initialized = true.
*
* 2. By manual cleanup code in this function's error paths before goto
* fail.
*
* Be careful to free resources in both cases!
*/
ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
QSLIST_INIT(&ctx->bh_list);
QSIMPLEQ_INIT(&ctx->bh_slice_list);
aio_context_setup(ctx);
ret = event_notifier_init(&ctx->notifier, false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to initialize event notifier");
goto fail;
}
/*
* Resources cannot easily be freed manually after aio_context_setup(). If
* you add any new resources to AioContext, it's probably best to acquire
* them before aio_context_setup().
*/
aio_context_setup(ctx);
g_source_set_can_recurse(&ctx->source, true);
qemu_lockcnt_init(&ctx->list_lock);
@ -623,9 +646,11 @@ AioContext *aio_context_new(Error **errp)
register_aiocontext(ctx);
ctx->initialized = true;
return ctx;
fail:
g_source_destroy(&ctx->source);
g_source_unref(&ctx->source);
return NULL;
}