| Message ID | 20230301205801.2453491-4-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | block: switch to AIO_WAIT_WHILE_UNLOCKED() where possible | expand |
On 1/3/23 21:57, Stefan Hajnoczi wrote: > The following conversion is safe and does not change behavior: > > GLOBAL_STATE_CODE(); > ... > - AIO_WAIT_WHILE(qemu_get_aio_context(), ...); > + AIO_WAIT_WHILE_UNLOCKED(NULL, ...); > > Since we're in GLOBAL_STATE_CODE(), qemu_get_aio_context() is our home > thread's AioContext. Thus AIO_WAIT_WHILE() does not unlock the > AioContext: > > if (ctx_ && in_aio_context_home_thread(ctx_)) { \ > while ((cond)) { \ > aio_poll(ctx_, true); \ > waited_ = true; \ > } \ > > And that means AIO_WAIT_WHILE_UNLOCKED(NULL, ...) can be substituted. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > block/graph-lock.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
On 2/3/23 11:19, Philippe Mathieu-Daudé wrote: > On 1/3/23 21:57, Stefan Hajnoczi wrote: >> The following conversion is safe and does not change behavior: >> >> GLOBAL_STATE_CODE(); >> ... >> - AIO_WAIT_WHILE(qemu_get_aio_context(), ...); >> + AIO_WAIT_WHILE_UNLOCKED(NULL, ...); >> >> Since we're in GLOBAL_STATE_CODE(), qemu_get_aio_context() is our home >> thread's AioContext. Thus AIO_WAIT_WHILE() does not unlock the >> AioContext: >> >> if (ctx_ && in_aio_context_home_thread(ctx_)) { \ >> while ((cond)) { \ >> aio_poll(ctx_, true); \ >> waited_ = true; \ >> } \ >> >> And that means AIO_WAIT_WHILE_UNLOCKED(NULL, ...) can be substituted. >> >> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> >> --- >> block/graph-lock.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) > > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
diff --git a/block/graph-lock.c b/block/graph-lock.c index 454c31e691..639526608f 100644 --- a/block/graph-lock.c +++ b/block/graph-lock.c @@ -127,7 +127,7 @@ void bdrv_graph_wrlock(void) * reader lock. */ qatomic_set(&has_writer, 0); - AIO_WAIT_WHILE(qemu_get_aio_context(), reader_count() >= 1); + AIO_WAIT_WHILE_UNLOCKED(NULL, reader_count() >= 1); qatomic_set(&has_writer, 1); /*
The following conversion is safe and does not change behavior: GLOBAL_STATE_CODE(); ... - AIO_WAIT_WHILE(qemu_get_aio_context(), ...); + AIO_WAIT_WHILE_UNLOCKED(NULL, ...); Since we're in GLOBAL_STATE_CODE(), qemu_get_aio_context() is our home thread's AioContext. Thus AIO_WAIT_WHILE() does not unlock the AioContext: if (ctx_ && in_aio_context_home_thread(ctx_)) { \ while ((cond)) { \ aio_poll(ctx_, true); \ waited_ = true; \ } \ And that means AIO_WAIT_WHILE_UNLOCKED(NULL, ...) can be substituted. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- block/graph-lock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)