io_uring/cmd: add cmd lazy tw wake helper

We want to use IOU_F_TWQ_LAZY_WAKE in commands. First, introduce a new
cmd tw helper accepting TWQ flags, and then add
io_uring_cmd_do_in_task_laz() that will pass IOU_F_TWQ_LAZY_WAKE and
imply the "lazy" semantics, i.e. it posts no more than 1 CQE and
delaying execution of this tw should not prevent forward progress.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5b9f6716006df7e817f18bd555aee2f8f9c8b0c3.1684154817.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 7fe31b2cd02f1ebac6c2fb8aaf476d07085f7ae2..bb9c666bd5840d7e0116b46a3bde0094e99a8407 100644 (file)
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -46,13 +46,23 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
                              struct iov_iter *iter, void *ioucmd);
 void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2,
                        unsigned issue_flags);
-void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
-                       void (*task_work_cb)(struct io_uring_cmd *, unsigned));
 struct sock *io_uring_get_socket(struct file *file);
 void __io_uring_cancel(bool cancel_all);
 void __io_uring_free(struct task_struct *tsk);
 void io_uring_unreg_ringfd(void);
 const char *io_uring_get_opcode(u8 opcode);
+void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd,
+                           void (*task_work_cb)(struct io_uring_cmd *, unsigned),
+                           unsigned flags);
+/* users should follow semantics of IOU_F_TWQ_LAZY_WAKE */
+void io_uring_cmd_do_in_task_lazy(struct io_uring_cmd *ioucmd,
+                       void (*task_work_cb)(struct io_uring_cmd *, unsigned));
+
+static inline void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
+                       void (*task_work_cb)(struct io_uring_cmd *, unsigned))
+{
+       __io_uring_cmd_do_in_task(ioucmd, task_work_cb, 0);
+}
 
 static inline void io_uring_files_cancel(void)
 {
@@ -85,6 +95,10 @@ static inline void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
                        void (*task_work_cb)(struct io_uring_cmd *, unsigned))
 {
 }
+static inline void io_uring_cmd_do_in_task_lazy(struct io_uring_cmd *ioucmd,
+                       void (*task_work_cb)(struct io_uring_cmd *, unsigned))
+{
+}
 static inline struct sock *io_uring_get_socket(struct file *file)
 {
        return NULL;

diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 5e32db48696d4bb0a46c48addc042b076a284ebf..476c7877ce587037edc5a937dc4173ba0c1f0752 100644 (file)
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -20,16 +20,24 @@ static void io_uring_cmd_work(struct io_kiocb *req, struct io_tw_state *ts)
        ioucmd->task_work_cb(ioucmd, issue_flags);
 }
 
-void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
-                       void (*task_work_cb)(struct io_uring_cmd *, unsigned))
+void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd,
+                       void (*task_work_cb)(struct io_uring_cmd *, unsigned),
+                       unsigned flags)
 {
        struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);
 
        ioucmd->task_work_cb = task_work_cb;
        req->io_task_work.func = io_uring_cmd_work;
-       io_req_task_work_add(req);
+       __io_req_task_work_add(req, flags);
+}
+EXPORT_SYMBOL_GPL(__io_uring_cmd_do_in_task);
+
+void io_uring_cmd_do_in_task_lazy(struct io_uring_cmd *ioucmd,
+                       void (*task_work_cb)(struct io_uring_cmd *, unsigned))
+{
+       __io_uring_cmd_do_in_task(ioucmd, task_work_cb, IOU_F_TWQ_LAZY_WAKE);
 }
-EXPORT_SYMBOL_GPL(io_uring_cmd_complete_in_task);
+EXPORT_SYMBOL_GPL(io_uring_cmd_do_in_task_lazy);
 
 static inline void io_req_set_cqe32_extra(struct io_kiocb *req,
                                          u64 extra1, u64 extra2)