On Thu, Mar 02, 2023 at 03:16:32PM +0100, Philippe Mathieu-Daudé wrote:
> On 2/3/23 14:08, Stefan Hajnoczi wrote:
> > On Thu, Mar 02, 2023 at 11:36:03AM +0100, Philippe Mathieu-Daudé wrote:
> > > On 1/3/23 21:57, Stefan Hajnoczi wrote:
> > > > There is no change in behavior. Switch to AIO_WAIT_WHILE_UNLOCKED()
> > > > instead of AIO_WAIT_WHILE() to document that this code has already been
> > > > audited and converted. The AioContext argument is already NULL so
> > > > aio_context_release() is never called anyway.
> > >
> > > Shouldn't we assert(ctx && unlock) in AIO_WAIT_WHILE_INTERNAL() then?
> >
> > Can you show where you'd add that assertion? It's not clear to me what
> > the purpose is.
>
> Without your series applied, using:
>
> -- >8 --
> diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
> index dd9a7f6461..dc372e4c16 100644
> --- a/include/block/aio-wait.h
> +++ b/include/block/aio-wait.h
> @@ -82,6 +82,8 @@ extern AioWait global_aio_wait;
> bool waited_ = false; \
> AioWait *wait_ = &global_aio_wait; \
> AioContext *ctx_ = (ctx); \
> + assert("Use AIO_WAIT_WHILE_UNLOCKED()" && !unlock \
> + || (ctx && strcmp(#ctx, "qemu_get_aio_context()"))); \
> /* Increment wait_->num_waiters before evaluating cond. */ \
> qatomic_inc(&wait_->num_waiters); \
> /* Paired with smp_mb in aio_wait_kick(). */ \
> ---
Ah, I see. You are suggesting adding an assertion to catch
AIO_WAIT_WHILE() usage in cases where AIO_WAIT_WHILE_UNLOCKED() should
be used instead.
I think it's a bit too clever, especially the strcmp trick, but we can
add it as the final patch. I have grepped the code and don't think there
are any remaining instances where the assertion fails.
Stefan
> I get:
>
> Assertion failed: ("Use AIO_WAIT_WHILE_UNLOCKED()" && !1 || (((void*)0) &&
> strcmp("((void*)0)", "qemu_get_aio_context()"))), function
> blk_exp_close_all_type, file export.c, line 309.
>
> -> [PATCH 2/6] block: convert blk_exp_close_all_type() to
> AIO_WAIT_WHILE_UNLOCKED()
>
> Assertion failed: ("Use AIO_WAIT_WHILE_UNLOCKED()" && !1 ||
> (qemu_get_aio_context() && strcmp("qemu_get_aio_context()",
> "qemu_get_aio_context()"))), function bdrv_graph_wrlock, file graph-lock.c,
> line 130.
>
> -> [PATCH 3/6] block: convert bdrv_graph_wrlock() to
> AIO_WAIT_WHILE_UNLOCKED()
>
> Assertion failed: ("Use AIO_WAIT_WHILE_UNLOCKED()" && !1 || (((void*)0) &&
> strcmp("((void*)0)", "qemu_get_aio_context()"))), function
> bdrv_drain_all_begin, file io.c, line 523.
>
> -> [PATCH 4/6] block: convert bdrv_drain_all_begin() to
> AIO_WAIT_WHILE_UNLOCKED()
>
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