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@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e492f0f11588bb5aa11d7d24e6f53b7c7628afdb.1709905727.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 0f52ea80103efcf46bd166c077fdc7827efe4def..65475b7aa03a372db2c6b85104f38c2b29f9aac0 100644 (file)
--- 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 5a4001139e288bfb3b4e89638d317487b8bd24c3..65947b9afc7157563eb60698379fb8be837dab20 100644 (file)
--- 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 dd6fe3b328f40e9673463a5734bda69468e4404f..c3c154790e45230a1d503173e287c6305ab22916 100644 (file)
--- 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);