Re: [PATCH v2] io_uring/net: ensure async prep handlers always initialize ->done_io

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On 3/16/24 23:58, Jens Axboe wrote:
On 3/16/24 11:42 AM, Pavel Begunkov wrote:
On 3/16/24 17:01, Jens Axboe wrote:
On 3/16/24 10:57 AM, Pavel Begunkov wrote:
On 3/16/24 16:51, Jens Axboe wrote:
On 3/16/24 10:46 AM, Pavel Begunkov wrote:
On 3/16/24 16:42, Jens Axboe wrote:
On 3/16/24 10:36 AM, Pavel Begunkov wrote:
On 3/16/24 16:36, Jens Axboe wrote:
...

It should only set REQ_F_EARLY_FAIL if we fail
_before_ prep is called

I did try both ways, fails if we just have:

Ok, but the point is that the sendzc's ->fail doesn't
need to be called unless you've done ->prep first.

But it fails, not sure how else to say it.

liburing tests? Which test case? If so, it should be another

Like I mentioned earlier, it's send zc and it's failing the test case
for that. test/send-zerocopy.t.

bug. REQ_F_NEED_CLEANUP is only set by opcodes, if a request is
terminated before ->prep is called, it means it never entered
any of the opdef callbacks and have never seen any of net.c
code, so there should be no REQ_F_NEED_CLEANUP, and so
io_sendrecv_fail() wouldn't try to set F_MORE. I don't know
what's wrong.

Feel free to take a look! I do like the simplicity of the early error
flag.

./send-zerocopy.t works fine

Huh, I wonder what I messed up. But:

My blind guess would be it called ->prep(), which is assumingly
failed, but then there was no ->fail() following it. BTW, we might
want to loose up that case, similar to mshots sendzc might decide
not to post notifications for any reason and the user should always
check F_MORE first.

@@ -2250,7 +2249,13 @@ static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
      int ret;
ret = io_init_req(ctx, req, sqe);
-    if (unlikely(ret))
+    if (unlikely(ret)) {
+        req->flags |= REQ_F_UNPREPPED_FAIL;
+        return io_submit_fail_init(sqe, req, ret);
+    }
+
+    ret = def->prep(req, sqe);
+    if (ret)
          return io_submit_fail_init(sqe, req, ret);

this obviously won't compile, assuming this is not the one you ran.

Urgh, yeah, some left unstaged



diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index ea7e5488b3be..de3a2c67c4a7 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -478,6 +478,7 @@ enum {
 	REQ_F_CAN_POLL_BIT,
 	REQ_F_BL_EMPTY_BIT,
 	REQ_F_BL_NO_RECYCLE_BIT,
+	REQ_F_UNPREPPED_FAIL_BIT,
/* not a real bit, just to check we're not overflowing the space */
 	__REQ_F_LAST_BIT,
@@ -556,6 +557,8 @@ enum {
 	REQ_F_BL_EMPTY		= IO_REQ_FLAG(REQ_F_BL_EMPTY_BIT),
 	/* don't recycle provided buffers for this request */
 	REQ_F_BL_NO_RECYCLE	= IO_REQ_FLAG(REQ_F_BL_NO_RECYCLE_BIT),
+
+	REQ_F_UNPREPPED_FAIL	= IO_REQ_FLAG(REQ_F_UNPREPPED_FAIL_BIT),
 };
typedef void (*io_req_tw_func_t)(struct io_kiocb *req, struct io_tw_state *ts);
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 846d67a9c72e..1231f8c53014 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -993,7 +993,7 @@ void io_req_defer_failed(struct io_kiocb *req, s32 res)
req_set_fail(req);
 	io_req_set_res(req, res, io_put_kbuf(req, IO_URING_F_UNLOCKED));
-	if (def->fail)
+	if (!(req->flags & REQ_F_UNPREPPED_FAIL) && def->fail)
 		def->fail(req);
 	io_req_complete_defer(req);
 }
@@ -2201,8 +2201,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		}
 		req->flags |= REQ_F_CREDS;
 	}
-
-	return def->prep(req, sqe);
+	return 0;
 }
static __cold int io_submit_fail_init(const struct io_uring_sqe *sqe,
@@ -2250,7 +2249,13 @@ static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	int ret;
ret = io_init_req(ctx, req, sqe);
-	if (unlikely(ret))
+	if (unlikely(ret)) {
+		req->flags |= REQ_F_UNPREPPED_FAIL;
+		return io_submit_fail_init(sqe, req, ret);
+	}
+
+	ret = io_issue_defs[req->opcode].prep(req, sqe);
+	if (ret)
 		return io_submit_fail_init(sqe, req, ret);
trace_io_uring_submit_req(req);


--
Pavel Begunkov




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