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 to cancel 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(). Driver callback is provided for canceling command in driver's way, meantime driver gets notified with exiting of io_uring task or context. Suggested-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- ublk patches: https://github.com/ming1/linux/commits/uring_exit_and_ublk include/linux/io_uring.h | 22 +++++++++++++++++- include/linux/io_uring_types.h | 6 +++++ include/uapi/linux/io_uring.h | 7 ++++-- io_uring/io_uring.c | 30 ++++++++++++++++++++++++ io_uring/uring_cmd.c | 42 ++++++++++++++++++++++++++++++++++ 5 files changed, 104 insertions(+), 3 deletions(-) diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h index 106cdc55ff3b..5b98308a154f 100644 --- a/include/linux/io_uring.h +++ b/include/linux/io_uring.h @@ -22,6 +22,9 @@ enum io_uring_cmd_flags { IO_URING_F_IOPOLL = (1 << 10), }; +typedef void (uring_cmd_cancel_fn)(struct io_uring_cmd *, + unsigned int issue_flags, struct task_struct *task); + struct io_uring_cmd { struct file *file; const struct io_uring_sqe *sqe; @@ -33,7 +36,17 @@ struct io_uring_cmd { }; u32 cmd_op; u32 flags; - u8 pdu[32]; /* available inline for free use */ + + /* less than 32 is available for cancelable cmd */ + union { + u8 pdu[32]; /* available inline for free use */ + + struct { + /* available inline for free use */ + u8 __pdu[32 - sizeof(uring_cmd_cancel_fn *)]; + uring_cmd_cancel_fn *cancel_fn; + }; + }; }; static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe) @@ -82,6 +95,8 @@ 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, uring_cmd_cancel_fn *fn); #else static inline int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw, struct iov_iter *iter, void *ioucmd) @@ -122,6 +137,11 @@ 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, uring_cmd_cancel_fn *fn) +{ + return -EOPNOTSUPP; +} #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..428cffb1a7e1 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3256,6 +3256,35 @@ 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); + + if (!cancel_all && req->task != task) + continue; + + /* safe to call ->cancel_fn() since cmd isn't done yet */ + if (cmd->flags & IORING_URING_CMD_CANCELABLE) { + cmd->cancel_fn(cmd, 0, task); + 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 +3336,7 @@ 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..47a6c84fd7f9 100644 --- a/io_uring/uring_cmd.c +++ b/io_uring/uring_cmd.c @@ -13,6 +13,46 @@ #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); + } +} + +/* + * cancel callback is called in io_uring_cancel_generic() for canceling + * this uring_cmd, and it is driver's responsibility to cover race between + * race between normal completion and canceling. + */ +int io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd, + unsigned int issue_flags, uring_cmd_cancel_fn *fn) +{ + struct io_kiocb *req = cmd_to_io_kiocb(cmd); + struct io_ring_ctx *ctx = req->ctx; + + if (!fn) + return -EINVAL; + + io_ring_submit_lock(ctx, issue_flags); + if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) { + cmd->cancel_fn = fn; + 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); + 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 +96,8 @@ 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); -- 2.40.1
