| Message ID | 20230922142816.2784777-1-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [V2] io_uring: cancelable uring_cmd | expand |
On 9/22/23 8:28 AM, Ming Lei wrote: > uring_cmd may never complete, such as ublk, in which uring cmd isn't > completed until one new block request is coming from ublk block device. > > Add cancelable uring_cmd to provide mechanism to driver for cancelling > pending commands in its own way. > > Add API of io_uring_cmd_mark_cancelable() for driver to mark one command as > cancelable, then io_uring will cancel this command in > io_uring_cancel_generic(). ->uring_cmd() callback is reused for canceling > command in driver's way, then driver gets notified with the cancelling > from io_uring. > > Add API of io_uring_cmd_get_task() to help driver cancel handler > deal with the canceling. This looks better, a few comments: > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > index 8e61f8b7c2ce..29a7a7e71f57 100644 > --- a/include/uapi/linux/io_uring.h > +++ b/include/uapi/linux/io_uring.h > @@ -249,10 +249,13 @@ enum io_uring_op { > * sqe->uring_cmd_flags > * IORING_URING_CMD_FIXED use registered buffer; pass this flag > * along with setting sqe->buf_index. > + * IORING_URING_CANCELABLE not for userspace > * IORING_URING_CMD_POLLED driver use only > */ > -#define IORING_URING_CMD_FIXED (1U << 0) > -#define IORING_URING_CMD_POLLED (1U << 31) > +#define IORING_URING_CMD_FIXED (1U << 0) > +/* set by driver, and handled by io_uring to cancel this cmd */ > +#define IORING_URING_CMD_CANCELABLE (1U << 30) > +#define IORING_URING_CMD_POLLED (1U << 31) If IORING_URING_CANCELABLE isn't UAPI, why stuff it in here? Should we have a split where we retain the upper 8 bits for internal use, or something like that? > diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c > index 783ed0fff71b..a3135fd47a4e 100644 > --- a/io_uring/io_uring.c > +++ b/io_uring/io_uring.c > @@ -3256,6 +3256,40 @@ static __cold bool io_uring_try_cancel_iowq(struct io_ring_ctx *ctx) > return ret; > } > > +static bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx, > + struct task_struct *task, bool cancel_all) > +{ > + struct hlist_node *tmp; > + struct io_kiocb *req; > + bool ret = false; > + > + mutex_lock(&ctx->uring_lock); > + hlist_for_each_entry_safe(req, tmp, &ctx->cancelable_uring_cmd, > + hash_node) { > + struct io_uring_cmd *cmd = io_kiocb_to_cmd(req, > + struct io_uring_cmd); > + struct file *file = req->file; > + > + if (WARN_ON_ONCE(!file->f_op->uring_cmd)) > + continue; > + > + if (!cancel_all && req->task != task) > + continue; > + > + if (cmd->flags & IORING_URING_CMD_CANCELABLE) { > + /* ->sqe isn't available if no async data */ > + if (!req_has_async_data(req)) > + cmd->sqe = NULL; > + file->f_op->uring_cmd(cmd, IO_URING_F_CANCEL); > + ret = true; > + } > + } > + io_submit_flush_completions(ctx); > + mutex_unlock(&ctx->uring_lock); > + > + return ret; > +} I think it'd be saner to drop uring_lock here, and then: > @@ -3307,6 +3341,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx, > ret |= io_kill_timeouts(ctx, task, cancel_all); > if (task) > ret |= io_run_task_work() > 0; > + ret |= io_uring_try_cancel_uring_cmd(ctx, task, cancel_all); > return ret; > } move this hunk into the uring_lock section. Also ensure that we do run task_work for cancelation, should the uring_cmd side require that (either now or eventually). > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > index 537795fddc87..d6b200a0be33 100644 > --- a/io_uring/uring_cmd.c > +++ b/io_uring/uring_cmd.c > @@ -13,6 +13,52 @@ > #include "rsrc.h" > #include "uring_cmd.h" > > +static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd, > + unsigned int issue_flags) > +{ > + if (cmd->flags & IORING_URING_CMD_CANCELABLE) { > + struct io_kiocb *req = cmd_to_io_kiocb(cmd); > + struct io_ring_ctx *ctx = req->ctx; > + > + io_ring_submit_lock(ctx, issue_flags); > + cmd->flags &= ~IORING_URING_CMD_CANCELABLE; > + hlist_del(&req->hash_node); > + io_ring_submit_unlock(ctx, issue_flags); > + } > +} static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd, unsigned int issue_flags) { struct io_kiocb *req = cmd_to_io_kiocb(cmd); struct io_ring_ctx *ctx = req->ctx; if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) return; io_ring_submit_lock(ctx, issue_flags); cmd->flags &= ~IORING_URING_CMD_CANCELABLE; hlist_del(&req->hash_node); io_ring_submit_unlock(ctx, issue_flags); } is cleaner imho. Minor nit. > + > +/* > + * Mark this command as concelable, then io_uring_try_cancel_uring_cmd() > + * will try to cancel this issued command by sending ->uring_cmd() with > + * issue_flags of IO_URING_F_CANCEL. > + * > + * The command is guaranteed to not be done when calling ->uring_cmd() > + * with IO_URING_F_CANCEL, but it is driver's responsibility to deal > + * with race between io_uring canceling and normal completion. > + */ > +int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, > + unsigned int issue_flags) > +{ > + struct io_kiocb *req = cmd_to_io_kiocb(cmd); > + struct io_ring_ctx *ctx = req->ctx; > + > + io_ring_submit_lock(ctx, issue_flags); > + if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) { > + cmd->flags |= IORING_URING_CMD_CANCELABLE; > + hlist_add_head(&req->hash_node, &ctx->cancelable_uring_cmd); > + } > + io_ring_submit_unlock(ctx, issue_flags); > + > + return 0; > +} A bit inconsistent here in terms of the locking. I'm assuming the marking happens within issue, in which case it should be fine to do: int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, unsigned int issue_flags) { struct io_kiocb *req = cmd_to_io_kiocb(cmd); struct io_ring_ctx *ctx = req->ctx; if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) { cmd->flags |= IORING_URING_CMD_CANCELABLE; io_ring_submit_lock(ctx, issue_flags); hlist_add_head(&req->hash_node, &ctx->cancelable_uring_cmd); io_ring_submit_unlock(ctx, issue_flags); } return 0; }
On Fri, Sep 22, 2023 at 09:02:44AM -0600, Jens Axboe wrote: > On 9/22/23 8:28 AM, Ming Lei wrote: > > uring_cmd may never complete, such as ublk, in which uring cmd isn't > > completed until one new block request is coming from ublk block device. > > > > Add cancelable uring_cmd to provide mechanism to driver for cancelling > > pending commands in its own way. > > > > Add API of io_uring_cmd_mark_cancelable() for driver to mark one command as > > cancelable, then io_uring will cancel this command in > > io_uring_cancel_generic(). ->uring_cmd() callback is reused for canceling > > command in driver's way, then driver gets notified with the cancelling > > from io_uring. > > > > Add API of io_uring_cmd_get_task() to help driver cancel handler > > deal with the canceling. > > This looks better, a few comments: > > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > > index 8e61f8b7c2ce..29a7a7e71f57 100644 > > --- a/include/uapi/linux/io_uring.h > > +++ b/include/uapi/linux/io_uring.h > > @@ -249,10 +249,13 @@ enum io_uring_op { > > * sqe->uring_cmd_flags > > * IORING_URING_CMD_FIXED use registered buffer; pass this flag > > * along with setting sqe->buf_index. > > + * IORING_URING_CANCELABLE not for userspace > > * IORING_URING_CMD_POLLED driver use only > > */ > > -#define IORING_URING_CMD_FIXED (1U << 0) > > -#define IORING_URING_CMD_POLLED (1U << 31) > > +#define IORING_URING_CMD_FIXED (1U << 0) > > +/* set by driver, and handled by io_uring to cancel this cmd */ > > +#define IORING_URING_CMD_CANCELABLE (1U << 30) > > +#define IORING_URING_CMD_POLLED (1U << 31) > > If IORING_URING_CANCELABLE isn't UAPI, why stuff it in here? Should we > have a split where we retain the upper 8 bits for internal use, or > something like that? Yeah, it is for internal use, same with IORING_URING_CMD_POLLED. I think we can retain upper 8 bits for internal use, and move the two definitions into kernel header. > > > diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c > > index 783ed0fff71b..a3135fd47a4e 100644 > > --- a/io_uring/io_uring.c > > +++ b/io_uring/io_uring.c > > @@ -3256,6 +3256,40 @@ static __cold bool io_uring_try_cancel_iowq(struct io_ring_ctx *ctx) > > return ret; > > } > > > > +static bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx, > > + struct task_struct *task, bool cancel_all) > > +{ > > + struct hlist_node *tmp; > > + struct io_kiocb *req; > > + bool ret = false; > > + > > + mutex_lock(&ctx->uring_lock); > > + hlist_for_each_entry_safe(req, tmp, &ctx->cancelable_uring_cmd, > > + hash_node) { > > + struct io_uring_cmd *cmd = io_kiocb_to_cmd(req, > > + struct io_uring_cmd); > > + struct file *file = req->file; > > + > > + if (WARN_ON_ONCE(!file->f_op->uring_cmd)) > > + continue; > > + > > + if (!cancel_all && req->task != task) > > + continue; > > + > > + if (cmd->flags & IORING_URING_CMD_CANCELABLE) { > > + /* ->sqe isn't available if no async data */ > > + if (!req_has_async_data(req)) > > + cmd->sqe = NULL; > > + file->f_op->uring_cmd(cmd, IO_URING_F_CANCEL); > > + ret = true; > > + } > > + } > > + io_submit_flush_completions(ctx); > > + mutex_unlock(&ctx->uring_lock); > > + > > + return ret; > > +} > > I think it'd be saner to drop uring_lock here, and then: > > > @@ -3307,6 +3341,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx, > > ret |= io_kill_timeouts(ctx, task, cancel_all); > > if (task) > > ret |= io_run_task_work() > 0; > > + ret |= io_uring_try_cancel_uring_cmd(ctx, task, cancel_all); > > return ret; > > } > > move this hunk into the uring_lock section. Also ensure that we do run > task_work for cancelation, should the uring_cmd side require that > (either now or eventually). OK, io_run_task_work() has run task_work already. > > > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > > index 537795fddc87..d6b200a0be33 100644 > > --- a/io_uring/uring_cmd.c > > +++ b/io_uring/uring_cmd.c > > @@ -13,6 +13,52 @@ > > #include "rsrc.h" > > #include "uring_cmd.h" > > > > +static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd, > > + unsigned int issue_flags) > > +{ > > + if (cmd->flags & IORING_URING_CMD_CANCELABLE) { > > + struct io_kiocb *req = cmd_to_io_kiocb(cmd); > > + struct io_ring_ctx *ctx = req->ctx; > > + > > + io_ring_submit_lock(ctx, issue_flags); > > + cmd->flags &= ~IORING_URING_CMD_CANCELABLE; > > + hlist_del(&req->hash_node); > > + io_ring_submit_unlock(ctx, issue_flags); > > + } > > +} > > static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd, > unsigned int issue_flags) > { > struct io_kiocb *req = cmd_to_io_kiocb(cmd); > struct io_ring_ctx *ctx = req->ctx; > > if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) > return; > > io_ring_submit_lock(ctx, issue_flags); > cmd->flags &= ~IORING_URING_CMD_CANCELABLE; > hlist_del(&req->hash_node); > io_ring_submit_unlock(ctx, issue_flags); > } > > is cleaner imho. Minor nit. > > > + > > +/* > > + * Mark this command as concelable, then io_uring_try_cancel_uring_cmd() > > + * will try to cancel this issued command by sending ->uring_cmd() with > > + * issue_flags of IO_URING_F_CANCEL. > > + * > > + * The command is guaranteed to not be done when calling ->uring_cmd() > > + * with IO_URING_F_CANCEL, but it is driver's responsibility to deal > > + * with race between io_uring canceling and normal completion. > > + */ > > +int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, > > + unsigned int issue_flags) > > +{ > > + struct io_kiocb *req = cmd_to_io_kiocb(cmd); > > + struct io_ring_ctx *ctx = req->ctx; > > + > > + io_ring_submit_lock(ctx, issue_flags); > > + if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) { > > + cmd->flags |= IORING_URING_CMD_CANCELABLE; > > + hlist_add_head(&req->hash_node, &ctx->cancelable_uring_cmd); > > + } > > + io_ring_submit_unlock(ctx, issue_flags); > > + > > + return 0; > > +} > > A bit inconsistent here in terms of the locking. I'm assuming the > marking happens within issue, in which case it should be fine to do: > > int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, > unsigned int issue_flags) > { > struct io_kiocb *req = cmd_to_io_kiocb(cmd); > struct io_ring_ctx *ctx = req->ctx; > > if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) { > cmd->flags |= IORING_URING_CMD_CANCELABLE; > io_ring_submit_lock(ctx, issue_flags); > hlist_add_head(&req->hash_node, &ctx->cancelable_uring_cmd); > io_ring_submit_unlock(ctx, issue_flags); > } OK, mask & clear bit can be moved out of lock in both two functions. Thanks, Ming
diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h index 106cdc55ff3b..205179a1c191 100644 --- a/include/linux/io_uring.h +++ b/include/linux/io_uring.h @@ -20,6 +20,9 @@ enum io_uring_cmd_flags { IO_URING_F_SQE128 = (1 << 8), IO_URING_F_CQE32 = (1 << 9), IO_URING_F_IOPOLL = (1 << 10), + + /* set when uring wants to cancel one issued command */ + IO_URING_F_CANCEL = (1 << 11), }; struct io_uring_cmd { @@ -82,6 +85,9 @@ static inline void io_uring_free(struct task_struct *tsk) __io_uring_free(tsk); } int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags); +int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, + unsigned int issue_flags); +struct task_struct *io_uring_cmd_get_task(struct io_uring_cmd *cmd); #else static inline int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw, struct iov_iter *iter, void *ioucmd) @@ -122,6 +128,15 @@ static inline int io_uring_cmd_sock(struct io_uring_cmd *cmd, { return -EOPNOTSUPP; } +static inline int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, + unsigned int issue_flags) +{ + return -EOPNOTSUPP; +} +static inline struct task_struct *io_uring_cmd_get_task(struct io_uring_cmd *cmd) +{ + return NULL; +} #endif #endif diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index 13d19b9be9f4..1571db76bec1 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -265,6 +265,12 @@ struct io_ring_ctx { */ struct io_wq_work_list iopoll_list; bool poll_multi_queue; + + /* + * Any cancelable uring_cmd is added to this list in + * ->uring_cmd() by io_uring_cmd_insert_cancelable() + */ + struct hlist_head cancelable_uring_cmd; } ____cacheline_aligned_in_smp; struct { diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index 8e61f8b7c2ce..29a7a7e71f57 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -249,10 +249,13 @@ enum io_uring_op { * sqe->uring_cmd_flags * IORING_URING_CMD_FIXED use registered buffer; pass this flag * along with setting sqe->buf_index. + * IORING_URING_CANCELABLE not for userspace * IORING_URING_CMD_POLLED driver use only */ -#define IORING_URING_CMD_FIXED (1U << 0) -#define IORING_URING_CMD_POLLED (1U << 31) +#define IORING_URING_CMD_FIXED (1U << 0) +/* set by driver, and handled by io_uring to cancel this cmd */ +#define IORING_URING_CMD_CANCELABLE (1U << 30) +#define IORING_URING_CMD_POLLED (1U << 31) /* diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 783ed0fff71b..a3135fd47a4e 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3256,6 +3256,40 @@ static __cold bool io_uring_try_cancel_iowq(struct io_ring_ctx *ctx) return ret; } +static bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx, + struct task_struct *task, bool cancel_all) +{ + struct hlist_node *tmp; + struct io_kiocb *req; + bool ret = false; + + mutex_lock(&ctx->uring_lock); + hlist_for_each_entry_safe(req, tmp, &ctx->cancelable_uring_cmd, + hash_node) { + struct io_uring_cmd *cmd = io_kiocb_to_cmd(req, + struct io_uring_cmd); + struct file *file = req->file; + + if (WARN_ON_ONCE(!file->f_op->uring_cmd)) + continue; + + if (!cancel_all && req->task != task) + continue; + + if (cmd->flags & IORING_URING_CMD_CANCELABLE) { + /* ->sqe isn't available if no async data */ + if (!req_has_async_data(req)) + cmd->sqe = NULL; + file->f_op->uring_cmd(cmd, IO_URING_F_CANCEL); + ret = true; + } + } + io_submit_flush_completions(ctx); + mutex_unlock(&ctx->uring_lock); + + return ret; +} + static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx, struct task_struct *task, bool cancel_all) @@ -3307,6 +3341,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx, ret |= io_kill_timeouts(ctx, task, cancel_all); if (task) ret |= io_run_task_work() > 0; + ret |= io_uring_try_cancel_uring_cmd(ctx, task, cancel_all); return ret; } diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c index 537795fddc87..d6b200a0be33 100644 --- a/io_uring/uring_cmd.c +++ b/io_uring/uring_cmd.c @@ -13,6 +13,52 @@ #include "rsrc.h" #include "uring_cmd.h" +static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd, + unsigned int issue_flags) +{ + if (cmd->flags & IORING_URING_CMD_CANCELABLE) { + struct io_kiocb *req = cmd_to_io_kiocb(cmd); + struct io_ring_ctx *ctx = req->ctx; + + io_ring_submit_lock(ctx, issue_flags); + cmd->flags &= ~IORING_URING_CMD_CANCELABLE; + hlist_del(&req->hash_node); + io_ring_submit_unlock(ctx, issue_flags); + } +} + +/* + * Mark this command as concelable, then io_uring_try_cancel_uring_cmd() + * will try to cancel this issued command by sending ->uring_cmd() with + * issue_flags of IO_URING_F_CANCEL. + * + * The command is guaranteed to not be done when calling ->uring_cmd() + * with IO_URING_F_CANCEL, but it is driver's responsibility to deal + * with race between io_uring canceling and normal completion. + */ +int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, + unsigned int issue_flags) +{ + struct io_kiocb *req = cmd_to_io_kiocb(cmd); + struct io_ring_ctx *ctx = req->ctx; + + io_ring_submit_lock(ctx, issue_flags); + if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) { + cmd->flags |= IORING_URING_CMD_CANCELABLE; + hlist_add_head(&req->hash_node, &ctx->cancelable_uring_cmd); + } + io_ring_submit_unlock(ctx, issue_flags); + + return 0; +} +EXPORT_SYMBOL_GPL(io_uring_cmd_mark_cancelable); + +struct task_struct *io_uring_cmd_get_task(struct io_uring_cmd *cmd) +{ + return cmd_to_io_kiocb(cmd)->task; +} +EXPORT_SYMBOL_GPL(io_uring_cmd_get_task); + static void io_uring_cmd_work(struct io_kiocb *req, struct io_tw_state *ts) { struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); @@ -56,6 +102,8 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2, { struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); + io_uring_cmd_del_cancelable(ioucmd, issue_flags); + if (ret < 0) req_set_fail(req);
uring_cmd may never complete, such as ublk, in which uring cmd isn't completed until one new block request is coming from ublk block device. Add cancelable uring_cmd to provide mechanism to driver for cancelling pending commands in its own way. Add API of io_uring_cmd_mark_cancelable() for driver to mark one command as cancelable, then io_uring will cancel this command in io_uring_cancel_generic(). ->uring_cmd() callback is reused for canceling command in driver's way, then driver gets notified with the cancelling from io_uring. Add API of io_uring_cmd_get_task() to help driver cancel handler deal with the canceling. Cc: Gabriel Krisman Bertazi <krisman@suse.de> Suggested-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ming Lei <ming.lei@redhat.com> --- ublk patches: https://github.com/ming1/linux/commits/uring_exit_and_ublk V2: - use ->uring_cmd() with IO_URING_F_CANCEL for canceling command include/linux/io_uring.h | 15 +++++++++++ include/linux/io_uring_types.h | 6 +++++ include/uapi/linux/io_uring.h | 7 +++-- io_uring/io_uring.c | 35 +++++++++++++++++++++++++ io_uring/uring_cmd.c | 48 ++++++++++++++++++++++++++++++++++ 5 files changed, 109 insertions(+), 2 deletions(-)