[PATCH for-next 1/2] io_uring/cmd: add cmd lazy tw wake helper

Pavel Begunkov
2023-05-15T12:57:50Z

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>
---
include/linux/io_uring.h | 18 ++++++++++++++++--
io_uring/uring_cmd.c | 16 ++++++++++++----
2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 7fe31b2cd02f..bb9c666bd584 100644
--- 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 5e32db48696d..476c7877ce58 100644
--- 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)
--
2.40.0