| Message ID | 20220118162738.1366281-2-eesposit@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Removal of Aiocontext lock through drains: protect bdrv_replace_child_noperm. | expand |
On Tue, Jan 18, 2022 at 11:27:27AM -0500, Emanuele Giuseppe Esposito wrote: > Same as BDRV_POLL_WHILE, but uses AIO_WAIT_WHILE_UNLOCKED. > > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> > --- > include/block/block-global-state.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h > index 419fe8427f..7ad9496f56 100644 > --- a/include/block/block-global-state.h > +++ b/include/block/block-global-state.h > @@ -158,6 +158,11 @@ void bdrv_drain_all(void); > AIO_WAIT_WHILE(bdrv_get_aio_context(bs_), \ > cond); }) > > +#define BDRV_POLL_WHILE_UNLOCKED(bs, cond) ({ \ > + BlockDriverState *bs_ = (bs); \ > + AIO_WAIT_WHILE_UNLOCKED(bdrv_get_aio_context(bs_), \ > + cond); }) No doc comments? When and why is this API useful? Are there any preconditions or assumptions (e.g. cond must be thread-safe)? Stefan
On 26/01/2022 11:49, Stefan Hajnoczi wrote: > On Tue, Jan 18, 2022 at 11:27:27AM -0500, Emanuele Giuseppe Esposito wrote: >> Same as BDRV_POLL_WHILE, but uses AIO_WAIT_WHILE_UNLOCKED. >> >> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> >> --- >> include/block/block-global-state.h | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h >> index 419fe8427f..7ad9496f56 100644 >> --- a/include/block/block-global-state.h >> +++ b/include/block/block-global-state.h >> @@ -158,6 +158,11 @@ void bdrv_drain_all(void); >> AIO_WAIT_WHILE(bdrv_get_aio_context(bs_), \ >> cond); }) >> >> +#define BDRV_POLL_WHILE_UNLOCKED(bs, cond) ({ \ >> + BlockDriverState *bs_ = (bs); \ >> + AIO_WAIT_WHILE_UNLOCKED(bdrv_get_aio_context(bs_), \ >> + cond); }) > > No doc comments? When and why is this API useful? Are there any > preconditions or assumptions (e.g. cond must be thread-safe)? > I am planning to add the following comment above the macro: /* * Unlocked counterpart of BDRV_POLL_WHILE. Uses AIO_WAIT_WHILE_UNLOCKED, * so it does not release+acquire the AioContext lock if we are in the * main loop, therefore the caller does not need to take it. * This function avoids taking the AioContext lock unnecessarly, so use * it only when sure that the lock is not taken already, otherwise it * might cause deadlocks. * * @cond must be thread-safe. */ Emanuele
On 2/3/22 14:57, Emanuele Giuseppe Esposito wrote: > * This function avoids taking the AioContext lock unnecessarly, so use > * it only when sure that the lock is not taken already, otherwise it > * might cause deadlocks. "so use" should be "but use". :) Paolo > * > * @cond must be thread-safe. > */
diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h index 419fe8427f..7ad9496f56 100644 --- a/include/block/block-global-state.h +++ b/include/block/block-global-state.h @@ -158,6 +158,11 @@ void bdrv_drain_all(void); AIO_WAIT_WHILE(bdrv_get_aio_context(bs_), \ cond); }) +#define BDRV_POLL_WHILE_UNLOCKED(bs, cond) ({ \ + BlockDriverState *bs_ = (bs); \ + AIO_WAIT_WHILE_UNLOCKED(bdrv_get_aio_context(bs_), \ + cond); }) + int bdrv_has_zero_init_1(BlockDriverState *bs); int bdrv_has_zero_init(BlockDriverState *bs); int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
Same as BDRV_POLL_WHILE, but uses AIO_WAIT_WHILE_UNLOCKED. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> --- include/block/block-global-state.h | 5 +++++ 1 file changed, 5 insertions(+)