On 5/16/23 11:00, Kanchan Joshi wrote:
On Mon, May 15, 2023 at 01:54:42PM +0100, Pavel Begunkov wrote:
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@xxxxxxxxx>
---
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 */
Should this also translate to some warn_on anywhere?
Would love to but don't see how. We can only check it doesn't
produce more than 1 CQE, but that would need
nr_cqes_before = cqes_ready();
tw_item->run();
WARN_ON(cqes_ready() >= nr_cqes_before + 1);
but that's just too ugly
+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);
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
+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);
+}
That should fail for nvme unless exported.
Any reason to export this? No one is using this at the moment.
+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);
Seems you did not want callers to pass the the new flag (LAZY_WAKE) and
therefore this helper.
Yep, I wouldn't mind exposing just *LAZY_WAKE but don't want
to let it use whatever flags there might be in the future.
Initially I wanted to just make io_uring_cmd_complete_in_task and
io_uring_cmd_do_in_task_lazy static inline, but that would need
some code shuffling to make it clean.
And if you did not want callers to know about this flag (internal
details of io_uring), it would be better to have two exported helpers
io_uring_cmd_do_in_task_lazy() and io_uring_cmd_complete_in_task().
Both will use the internal helper __io_uring_cmd_do_in_task with
different flag.
That's how it should be in this patch
--
Pavel Begunkov
