| Message ID | a3928d3de14d2569efc2edd7fb654a4795ae7f86.1710720150.git.asml.silence@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | remove aux CQE caches | expand |
On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: > uring_cmd implementations should not try to guess issue_flags, just use > a newly added io_uring_cmd_complete(). We're loosing an optimisation in > the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption > is that we don't care that much about it. > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com > Signed-off-by: Jens Axboe <axboe@kernel.dk> > --- > drivers/block/ublk_drv.c | 18 ++++++++---------- > 1 file changed, 8 insertions(+), 10 deletions(-) > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > index bea3d5cf8a83..97dceecadab2 100644 > --- a/drivers/block/ublk_drv.c > +++ b/drivers/block/ublk_drv.c > @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) > return true; > } > > -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > - unsigned int issue_flags) > +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) > { > bool done; > > @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > spin_unlock(&ubq->cancel_lock); > > if (!done) > - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); > + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); > } > > /* > * The ublk char device won't be closed when calling cancel fn, so both > * ublk device and queue are guaranteed to be live > */ > -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > - unsigned int issue_flags) > +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) > { > struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); > struct ublk_queue *ubq = pdu->ubq; > @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > io = &ubq->ios[pdu->tag]; > WARN_ON_ONCE(io->cmd != cmd); > - ublk_cancel_cmd(ubq, io, issue_flags); > + ublk_cancel_cmd(ubq, io); .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't be removed, otherwise double task run is caused because .cancel_fn can be called multiple times if the request stays in ctx->cancelable_uring_cmd. Thanks, Ming
On 3/18/24 08:16, Ming Lei wrote: > On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: >> uring_cmd implementations should not try to guess issue_flags, just use >> a newly added io_uring_cmd_complete(). We're loosing an optimisation in >> the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption >> is that we don't care that much about it. >> >> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> >> Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com >> Signed-off-by: Jens Axboe <axboe@kernel.dk> >> --- >> drivers/block/ublk_drv.c | 18 ++++++++---------- >> 1 file changed, 8 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c >> index bea3d5cf8a83..97dceecadab2 100644 >> --- a/drivers/block/ublk_drv.c >> +++ b/drivers/block/ublk_drv.c >> @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) >> return true; >> } >> >> -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >> - unsigned int issue_flags) >> +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) >> { >> bool done; >> >> @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >> spin_unlock(&ubq->cancel_lock); >> >> if (!done) >> - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); >> + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); >> } >> >> /* >> * The ublk char device won't be closed when calling cancel fn, so both >> * ublk device and queue are guaranteed to be live >> */ >> -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >> - unsigned int issue_flags) >> +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) >> { >> struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); >> struct ublk_queue *ubq = pdu->ubq; >> @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >> >> io = &ubq->ios[pdu->tag]; >> WARN_ON_ONCE(io->cmd != cmd); >> - ublk_cancel_cmd(ubq, io, issue_flags); >> + ublk_cancel_cmd(ubq, io); > > .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't > be removed, otherwise double task run is caused because .cancel_fn > can be called multiple times if the request stays in ctx->cancelable_uring_cmd. I see, that's exactly why I was asking whether it can be deferred to tw. Let me see if I can get by without that patch, but honestly it's a horrible abuse of the ring state. Any ideas how that can be cleaned up?
On 3/18/24 12:52, Pavel Begunkov wrote: > On 3/18/24 08:16, Ming Lei wrote: >> On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: >>> uring_cmd implementations should not try to guess issue_flags, just use >>> a newly added io_uring_cmd_complete(). We're loosing an optimisation in >>> the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption >>> is that we don't care that much about it. >>> >>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> >>> Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com >>> Signed-off-by: Jens Axboe <axboe@kernel.dk> >>> --- >>> drivers/block/ublk_drv.c | 18 ++++++++---------- >>> 1 file changed, 8 insertions(+), 10 deletions(-) >>> >>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c >>> index bea3d5cf8a83..97dceecadab2 100644 >>> --- a/drivers/block/ublk_drv.c >>> +++ b/drivers/block/ublk_drv.c >>> @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) >>> return true; >>> } >>> -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >>> - unsigned int issue_flags) >>> +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) >>> { >>> bool done; >>> @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >>> spin_unlock(&ubq->cancel_lock); >>> if (!done) >>> - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); >>> + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); >>> } >>> /* >>> * The ublk char device won't be closed when calling cancel fn, so both >>> * ublk device and queue are guaranteed to be live >>> */ >>> -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >>> - unsigned int issue_flags) >>> +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) >>> { >>> struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); >>> struct ublk_queue *ubq = pdu->ubq; >>> @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >>> io = &ubq->ios[pdu->tag]; >>> WARN_ON_ONCE(io->cmd != cmd); >>> - ublk_cancel_cmd(ubq, io, issue_flags); >>> + ublk_cancel_cmd(ubq, io); >> >> .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't >> be removed, otherwise double task run is caused because .cancel_fn >> can be called multiple times if the request stays in ctx->cancelable_uring_cmd. > > I see, that's exactly why I was asking whether it can be deferred > to tw. Let me see if I can get by without that patch, but honestly > it's a horrible abuse of the ring state. Any ideas how that can be > cleaned up? I assume io_uring_try_cancel_uring_cmd() can run in parallel with completions, so there can be two parallel calls calls to ->uring_cmd (e.g. io-wq + cancel), which gives me shivers. Also, I'd rather no cancel in place requests of another task, io_submit_flush_completions() but it complicates things. Is there any argument against removing requests from the cancellation list in io_uring_try_cancel_uring_cmd() before calling ->uring_cmd? io_uring_try_cancel_uring_cmd() { lock(); for_each_req() { remove_req_from_cancel_list(req); req->file->uring_cmd(); } unlock(); }
On 3/18/24 13:37, Pavel Begunkov wrote: > On 3/18/24 12:52, Pavel Begunkov wrote: >> On 3/18/24 08:16, Ming Lei wrote: >>> On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: >>>> uring_cmd implementations should not try to guess issue_flags, just use >>>> a newly added io_uring_cmd_complete(). We're loosing an optimisation in >>>> the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption >>>> is that we don't care that much about it. >>>> >>>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> >>>> Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com >>>> Signed-off-by: Jens Axboe <axboe@kernel.dk> >>>> --- >>>> drivers/block/ublk_drv.c | 18 ++++++++---------- >>>> 1 file changed, 8 insertions(+), 10 deletions(-) >>>> >>>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c >>>> index bea3d5cf8a83..97dceecadab2 100644 >>>> --- a/drivers/block/ublk_drv.c >>>> +++ b/drivers/block/ublk_drv.c >>>> @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) >>>> return true; >>>> } >>>> -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >>>> - unsigned int issue_flags) >>>> +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) >>>> { >>>> bool done; >>>> @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >>>> spin_unlock(&ubq->cancel_lock); >>>> if (!done) >>>> - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); >>>> + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); >>>> } >>>> /* >>>> * The ublk char device won't be closed when calling cancel fn, so both >>>> * ublk device and queue are guaranteed to be live >>>> */ >>>> -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >>>> - unsigned int issue_flags) >>>> +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) >>>> { >>>> struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); >>>> struct ublk_queue *ubq = pdu->ubq; >>>> @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >>>> io = &ubq->ios[pdu->tag]; >>>> WARN_ON_ONCE(io->cmd != cmd); >>>> - ublk_cancel_cmd(ubq, io, issue_flags); >>>> + ublk_cancel_cmd(ubq, io); >>> >>> .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't >>> be removed, otherwise double task run is caused because .cancel_fn >>> can be called multiple times if the request stays in ctx->cancelable_uring_cmd. >> >> I see, that's exactly why I was asking whether it can be deferred >> to tw. Let me see if I can get by without that patch, but honestly >> it's a horrible abuse of the ring state. Any ideas how that can be >> cleaned up? > > I assume io_uring_try_cancel_uring_cmd() can run in parallel with > completions, so there can be two parallel calls calls to ->uring_cmd > (e.g. io-wq + cancel), which gives me shivers. Also, I'd rather > no cancel in place requests of another task, io_submit_flush_completions() > but it complicates things. I'm wrong though on flush_completions, the task there cancels only its own requests io_uring_try_cancel_uring_cmd() { ... if (!cancel_all && req->task != task) continue; } > Is there any argument against removing requests from the cancellation > list in io_uring_try_cancel_uring_cmd() before calling ->uring_cmd? > > io_uring_try_cancel_uring_cmd() { > lock(); > for_each_req() { > remove_req_from_cancel_list(req); > req->file->uring_cmd(); > } > unlock(); > } >
On Mon, Mar 18, 2024 at 12:52:33PM +0000, Pavel Begunkov wrote: > On 3/18/24 08:16, Ming Lei wrote: > > On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: > > > uring_cmd implementations should not try to guess issue_flags, just use > > > a newly added io_uring_cmd_complete(). We're loosing an optimisation in > > > the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption > > > is that we don't care that much about it. > > > > > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > > > Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com > > > Signed-off-by: Jens Axboe <axboe@kernel.dk> > > > --- > > > drivers/block/ublk_drv.c | 18 ++++++++---------- > > > 1 file changed, 8 insertions(+), 10 deletions(-) > > > > > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > > > index bea3d5cf8a83..97dceecadab2 100644 > > > --- a/drivers/block/ublk_drv.c > > > +++ b/drivers/block/ublk_drv.c > > > @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) > > > return true; > > > } > > > -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > - unsigned int issue_flags) > > > +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) > > > { > > > bool done; > > > @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > spin_unlock(&ubq->cancel_lock); > > > if (!done) > > > - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); > > > + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); > > > } > > > /* > > > * The ublk char device won't be closed when calling cancel fn, so both > > > * ublk device and queue are guaranteed to be live > > > */ > > > -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > - unsigned int issue_flags) > > > +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) > > > { > > > struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); > > > struct ublk_queue *ubq = pdu->ubq; > > > @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > io = &ubq->ios[pdu->tag]; > > > WARN_ON_ONCE(io->cmd != cmd); > > > - ublk_cancel_cmd(ubq, io, issue_flags); > > > + ublk_cancel_cmd(ubq, io); > > > > .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't > > be removed, otherwise double task run is caused because .cancel_fn > > can be called multiple times if the request stays in ctx->cancelable_uring_cmd. > > I see, that's exactly why I was asking whether it can be deferred > to tw. Let me see if I can get by without that patch, but honestly > it's a horrible abuse of the ring state. Any ideas how that can be > cleaned up? Simply deferring io_uring_cmd_done() in ublk_cancel_cmd() to tw still triggers warning in __put_task_struct(), so I'd suggest to add the patch until it is root-cause & fixed. Thanks, Ming
On Mon, Mar 18, 2024 at 02:32:16PM +0000, Pavel Begunkov wrote: > On 3/18/24 13:37, Pavel Begunkov wrote: > > On 3/18/24 12:52, Pavel Begunkov wrote: > > > On 3/18/24 08:16, Ming Lei wrote: > > > > On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: > > > > > uring_cmd implementations should not try to guess issue_flags, just use > > > > > a newly added io_uring_cmd_complete(). We're loosing an optimisation in > > > > > the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption > > > > > is that we don't care that much about it. > > > > > > > > > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > > > > > Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com > > > > > Signed-off-by: Jens Axboe <axboe@kernel.dk> > > > > > --- > > > > > drivers/block/ublk_drv.c | 18 ++++++++---------- > > > > > 1 file changed, 8 insertions(+), 10 deletions(-) > > > > > > > > > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > > > > > index bea3d5cf8a83..97dceecadab2 100644 > > > > > --- a/drivers/block/ublk_drv.c > > > > > +++ b/drivers/block/ublk_drv.c > > > > > @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) > > > > > return true; > > > > > } > > > > > -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > > > - unsigned int issue_flags) > > > > > +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) > > > > > { > > > > > bool done; > > > > > @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > > > spin_unlock(&ubq->cancel_lock); > > > > > if (!done) > > > > > - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); > > > > > + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); > > > > > } > > > > > /* > > > > > * The ublk char device won't be closed when calling cancel fn, so both > > > > > * ublk device and queue are guaranteed to be live > > > > > */ > > > > > -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > > > - unsigned int issue_flags) > > > > > +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) > > > > > { > > > > > struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); > > > > > struct ublk_queue *ubq = pdu->ubq; > > > > > @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > > > io = &ubq->ios[pdu->tag]; > > > > > WARN_ON_ONCE(io->cmd != cmd); > > > > > - ublk_cancel_cmd(ubq, io, issue_flags); > > > > > + ublk_cancel_cmd(ubq, io); > > > > > > > > .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't > > > > be removed, otherwise double task run is caused because .cancel_fn > > > > can be called multiple times if the request stays in ctx->cancelable_uring_cmd. > > > > > > I see, that's exactly why I was asking whether it can be deferred > > > to tw. Let me see if I can get by without that patch, but honestly > > > it's a horrible abuse of the ring state. Any ideas how that can be > > > cleaned up? > > > > I assume io_uring_try_cancel_uring_cmd() can run in parallel with > > completions, so there can be two parallel calls calls to ->uring_cmd > > (e.g. io-wq + cancel), which gives me shivers. Also, I'd rather > > no cancel in place requests of another task, io_submit_flush_completions() > > but it complicates things. > > I'm wrong though on flush_completions, the task there cancels only > its own requests > > io_uring_try_cancel_uring_cmd() { > ... > if (!cancel_all && req->task != task) > continue; > } > > > > Is there any argument against removing requests from the cancellation > > list in io_uring_try_cancel_uring_cmd() before calling ->uring_cmd? > > > > io_uring_try_cancel_uring_cmd() { > > lock(); > > for_each_req() { > > remove_req_from_cancel_list(req); > > req->file->uring_cmd(); > > } > > unlock(); Also the req may not be ready to cancel in ->uring_cmd(), so it should be allowed to retry in future if it isn't canceled this time. Thanks, Ming
On 3/18/24 14:34, Ming Lei wrote: > On Mon, Mar 18, 2024 at 12:52:33PM +0000, Pavel Begunkov wrote: >> On 3/18/24 08:16, Ming Lei wrote: >>> On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: >>>> uring_cmd implementations should not try to guess issue_flags, just use >>>> a newly added io_uring_cmd_complete(). We're loosing an optimisation in >>>> the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption >>>> is that we don't care that much about it. >>>> >>>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> >>>> Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com >>>> Signed-off-by: Jens Axboe <axboe@kernel.dk> >>>> --- >>>> drivers/block/ublk_drv.c | 18 ++++++++---------- >>>> 1 file changed, 8 insertions(+), 10 deletions(-) >>>> >>>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c >>>> index bea3d5cf8a83..97dceecadab2 100644 >>>> --- a/drivers/block/ublk_drv.c >>>> +++ b/drivers/block/ublk_drv.c >>>> @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) >>>> return true; >>>> } >>>> -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >>>> - unsigned int issue_flags) >>>> +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) >>>> { >>>> bool done; >>>> @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, >>>> spin_unlock(&ubq->cancel_lock); >>>> if (!done) >>>> - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); >>>> + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); >>>> } >>>> /* >>>> * The ublk char device won't be closed when calling cancel fn, so both >>>> * ublk device and queue are guaranteed to be live >>>> */ >>>> -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >>>> - unsigned int issue_flags) >>>> +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) >>>> { >>>> struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); >>>> struct ublk_queue *ubq = pdu->ubq; >>>> @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, >>>> io = &ubq->ios[pdu->tag]; >>>> WARN_ON_ONCE(io->cmd != cmd); >>>> - ublk_cancel_cmd(ubq, io, issue_flags); >>>> + ublk_cancel_cmd(ubq, io); >>> >>> .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't >>> be removed, otherwise double task run is caused because .cancel_fn >>> can be called multiple times if the request stays in ctx->cancelable_uring_cmd. >> >> I see, that's exactly why I was asking whether it can be deferred >> to tw. Let me see if I can get by without that patch, but honestly >> it's a horrible abuse of the ring state. Any ideas how that can be >> cleaned up? > > Simply deferring io_uring_cmd_done() in ublk_cancel_cmd() to tw still triggers > warning in __put_task_struct(), so I'd suggest to add the patch until > it is root-cause & fixed. I mean drop the patch[es] changing how ublk passes issue_flags around, moving cancellation point and all related, and leave it to later really hoping we'll figure how to do it better.
On Mon, Mar 18, 2024 at 03:08:19PM +0000, Pavel Begunkov wrote: > On 3/18/24 14:34, Ming Lei wrote: > > On Mon, Mar 18, 2024 at 12:52:33PM +0000, Pavel Begunkov wrote: > > > On 3/18/24 08:16, Ming Lei wrote: > > > > On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: > > > > > uring_cmd implementations should not try to guess issue_flags, just use > > > > > a newly added io_uring_cmd_complete(). We're loosing an optimisation in > > > > > the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption > > > > > is that we don't care that much about it. > > > > > > > > > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > > > > > Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com > > > > > Signed-off-by: Jens Axboe <axboe@kernel.dk> > > > > > --- > > > > > drivers/block/ublk_drv.c | 18 ++++++++---------- > > > > > 1 file changed, 8 insertions(+), 10 deletions(-) > > > > > > > > > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > > > > > index bea3d5cf8a83..97dceecadab2 100644 > > > > > --- a/drivers/block/ublk_drv.c > > > > > +++ b/drivers/block/ublk_drv.c > > > > > @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) > > > > > return true; > > > > > } > > > > > -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > > > - unsigned int issue_flags) > > > > > +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) > > > > > { > > > > > bool done; > > > > > @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > > > spin_unlock(&ubq->cancel_lock); > > > > > if (!done) > > > > > - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); > > > > > + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); > > > > > } > > > > > /* > > > > > * The ublk char device won't be closed when calling cancel fn, so both > > > > > * ublk device and queue are guaranteed to be live > > > > > */ > > > > > -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > > > - unsigned int issue_flags) > > > > > +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) > > > > > { > > > > > struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); > > > > > struct ublk_queue *ubq = pdu->ubq; > > > > > @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > > > io = &ubq->ios[pdu->tag]; > > > > > WARN_ON_ONCE(io->cmd != cmd); > > > > > - ublk_cancel_cmd(ubq, io, issue_flags); > > > > > + ublk_cancel_cmd(ubq, io); > > > > > > > > .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't > > > > be removed, otherwise double task run is caused because .cancel_fn > > > > can be called multiple times if the request stays in ctx->cancelable_uring_cmd. > > > > > > I see, that's exactly why I was asking whether it can be deferred > > > to tw. Let me see if I can get by without that patch, but honestly > > > it's a horrible abuse of the ring state. Any ideas how that can be > > > cleaned up? > > > > Simply deferring io_uring_cmd_done() in ublk_cancel_cmd() to tw still triggers > > warning in __put_task_struct(), so I'd suggest to add the patch until > > it is root-cause & fixed. > > I mean drop the patch[es] changing how ublk passes issue_flags > around, moving cancellation point and all related, and leave it > to later really hoping we'll figure how to do it better. Looks fine for me. Thanks, Ming
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index bea3d5cf8a83..97dceecadab2 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) return true; } -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, - unsigned int issue_flags) +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) { bool done; @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, spin_unlock(&ubq->cancel_lock); if (!done) - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); + io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); } /* * The ublk char device won't be closed when calling cancel fn, so both * ublk device and queue are guaranteed to be live */ -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, - unsigned int issue_flags) +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) { struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); struct ublk_queue *ubq = pdu->ubq; @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, io = &ubq->ios[pdu->tag]; WARN_ON_ONCE(io->cmd != cmd); - ublk_cancel_cmd(ubq, io, issue_flags); + ublk_cancel_cmd(ubq, io); if (need_schedule) { if (ublk_can_use_recovery(ub)) @@ -1484,7 +1482,7 @@ static void ublk_cancel_queue(struct ublk_queue *ubq) int i; for (i = 0; i < ubq->q_depth; i++) - ublk_cancel_cmd(ubq, &ubq->ios[i], IO_URING_F_UNLOCKED); + ublk_cancel_cmd(ubq, &ubq->ios[i]); } /* Cancel all pending commands, must be called after del_gendisk() returns */ @@ -1777,7 +1775,7 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd, return -EIOCBQUEUED; out: - io_uring_cmd_done(cmd, ret, 0, issue_flags); + io_uring_cmd_complete(cmd, ret, 0); pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n", __func__, cmd_op, tag, ret, io->flags); return -EIOCBQUEUED; @@ -1842,7 +1840,7 @@ static void ublk_ch_uring_cmd_cb(struct io_uring_cmd *cmd, static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) { if (unlikely(issue_flags & IO_URING_F_CANCEL)) { - ublk_uring_cmd_cancel_fn(cmd, issue_flags); + ublk_uring_cmd_cancel_fn(cmd); return 0; } @@ -2930,7 +2928,7 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, if (ub) ublk_put_device(ub); out: - io_uring_cmd_done(cmd, ret, 0, issue_flags); + io_uring_cmd_complete(cmd, ret, 0); pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n", __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id); return -EIOCBQUEUED;