On 4/8/24 3:11 AM, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 6.8-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> To reproduce the conflict and resubmit, you may use the following commands:
>
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.8.y
> git checkout FETCH_HEAD
> git cherry-pick -x bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2024040826-handbrake-five-e04e@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..
Here's the dependency and the patch itself backported, please add for
6.8. Thanks!
--
Jens Axboe
From 5984bb9e2b72455e8e5a1925edde3079c9f949be Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Mon, 1 Apr 2024 11:30:06 -0600
Subject: [PATCH 2/2] io_uring: disable io-wq execution of multishot NOWAIT
requests
Commit bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b upstream.
Do the same check for direct io-wq execution for multishot requests that
commit 2a975d426c82 did for the inline execution, and disable multishot
mode (and revert to single shot) if the file type doesn't support NOWAIT,
and isn't opened in O_NONBLOCK mode. For multishot to work properly, it's
a requirement that nonblocking read attempts can be done.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
io_uring/io_uring.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 6fdcb5e07807..1a9f96ed259e 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1964,10 +1964,15 @@ void io_wq_submit_work(struct io_wq_work *work)
err = -EBADFD;
if (!file_can_poll(req->file))
goto fail;
- err = -ECANCELED;
- if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
- goto fail;
- return;
+ if (req->file->f_flags & O_NONBLOCK ||
+ req->file->f_mode & FMODE_NOWAIT) {
+ err = -ECANCELED;
+ if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
+ goto fail;
+ return;
+ } else {
+ req->flags &= ~REQ_F_APOLL_MULTISHOT;
+ }
}
if (req->flags & REQ_F_FORCE_ASYNC) {
--
2.43.0
From 6fa8da25be5ad285fae51584ce1d461fec42bd94 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date: Fri, 8 Mar 2024 13:55:57 +0000
Subject: [PATCH 1/2] io_uring: refactor DEFER_TASKRUN multishot checks
Commit e0e4ab52d17096d96c21a6805ccd424b283c3c6d upstream.
We disallow DEFER_TASKRUN multishots from running by io-wq, which is
checked by individual opcodes in the issue path. We can consolidate all
it in io_wq_submit_work() at the same time moving the checks out of the
hot path.
Suggested-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/e492f0f11588bb5aa11d7d24e6f53b7c7628afdb.1709905727.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
io_uring/io_uring.c | 20 ++++++++++++++++++++
io_uring/net.c | 21 ---------------------
io_uring/rw.c | 2 --
3 files changed, 20 insertions(+), 23 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 572effd0af53..6fdcb5e07807 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -949,6 +949,8 @@ bool io_fill_cqe_req_aux(struct io_kiocb *req, bool defer, s32 res, u32 cflags)
u64 user_data = req->cqe.user_data;
struct io_uring_cqe *cqe;
+ lockdep_assert(!io_wq_current_is_worker());
+
if (!defer)
return __io_post_aux_cqe(ctx, user_data, res, cflags, false);
@@ -1950,6 +1952,24 @@ void io_wq_submit_work(struct io_wq_work *work)
goto fail;
}
+ /*
+ * If DEFER_TASKRUN is set, it's only allowed to post CQEs from the
+ * submitter task context. Final request completions are handed to the
+ * right context, however this is not the case of auxiliary CQEs,
+ * which is the main mean of operation for multishot requests.
+ * Don't allow any multishot execution from io-wq. It's more restrictive
+ * than necessary and also cleaner.
+ */
+ if (req->flags & REQ_F_APOLL_MULTISHOT) {
+ err = -EBADFD;
+ if (!file_can_poll(req->file))
+ goto fail;
+ err = -ECANCELED;
+ if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
+ goto fail;
+ return;
+ }
+
if (req->flags & REQ_F_FORCE_ASYNC) {
bool opcode_poll = def->pollin || def->pollout;
diff --git a/io_uring/net.c b/io_uring/net.c
index 5a4001139e28..65947b9afc71 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -78,19 +78,6 @@ struct io_sr_msg {
*/
#define MULTISHOT_MAX_RETRY 32
-static inline bool io_check_multishot(struct io_kiocb *req,
- unsigned int issue_flags)
-{
- /*
- * When ->locked_cq is set we only allow to post CQEs from the original
- * task context. Usual request completions will be handled in other
- * generic paths but multipoll may decide to post extra cqes.
- */
- return !(issue_flags & IO_URING_F_IOWQ) ||
- !(req->flags & REQ_F_APOLL_MULTISHOT) ||
- !req->ctx->task_complete;
-}
-
int io_shutdown_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_shutdown *shutdown = io_kiocb_to_cmd(req, struct io_shutdown);
@@ -837,9 +824,6 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
(sr->flags & IORING_RECVSEND_POLL_FIRST))
return io_setup_async_msg(req, kmsg, issue_flags);
- if (!io_check_multishot(req, issue_flags))
- return io_setup_async_msg(req, kmsg, issue_flags);
-
retry_multishot:
if (io_do_buffer_select(req)) {
void __user *buf;
@@ -935,9 +919,6 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
(sr->flags & IORING_RECVSEND_POLL_FIRST))
return -EAGAIN;
- if (!io_check_multishot(req, issue_flags))
- return -EAGAIN;
-
sock = sock_from_file(req->file);
if (unlikely(!sock))
return -ENOTSOCK;
@@ -1386,8 +1367,6 @@ int io_accept(struct io_kiocb *req, unsigned int issue_flags)
struct file *file;
int ret, fd;
- if (!io_check_multishot(req, issue_flags))
- return -EAGAIN;
retry:
if (!fixed) {
fd = __get_unused_fd_flags(accept->flags, accept->nofile);
diff --git a/io_uring/rw.c b/io_uring/rw.c
index dd6fe3b328f4..c3c154790e45 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -932,8 +932,6 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
*/
if (!file_can_poll(req->file))
return -EBADFD;
- if (issue_flags & IO_URING_F_IOWQ)
- return -EAGAIN;
ret = __io_read(req, issue_flags);
--
2.43.0
