[PATCH v1 1/1] [io_uring] don't stall on submission errors

From: "Stefan Bühler" <source@stbuehler.de>
To: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH v1 1/1] [io_uring] don't stall on submission errors
Date: Wed,  1 May 2019 13:49:55 +0200	[thread overview]
Message-ID: <20190501114955.13103-1-source@stbuehler.de> (raw)
In-Reply-To: <fc1f2755-2c79-f5de-4057-ff658f3919ca@kernel.dk>

Stalling is buggy right now, because it might wait for too many events;
for proper stalling we'd need to know how many submissions we ignored,
and reduce min_complete by that amount.

Easier not to stall at all.

Also fix some local variable names.

Should probably be merged with commit
fd25de20d38dd07e2ce7108986f1fd08f9bf03d4:
    io_uring: have submission side sqe errors post a cqe

Signed-off-by: Stefan Bühler <source@stbuehler.de>
---
 fs/io_uring.c | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e614a675a1e0..17eae94a54fc 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1846,7 +1846,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
 			  unsigned int nr, bool has_user, bool mm_fault)
 {
 	struct io_submit_state state, *statep = NULL;
-	int ret, i, submitted = 0;
+	int ret, i, inflight = 0;
 
 	if (nr > IO_PLUG_THRESHOLD) {
 		io_submit_state_start(&state, ctx, nr);
@@ -1863,7 +1863,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
 			ret = io_submit_sqe(ctx, &sqes[i], statep);
 		}
 		if (!ret) {
-			submitted++;
+			inflight++;
 			continue;
 		}
 
@@ -1873,7 +1873,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
 	if (statep)
 		io_submit_state_end(&state);
 
-	return submitted;
+	return inflight;
 }
 
 static int io_sq_thread(void *data)
@@ -2011,7 +2011,7 @@ static int io_sq_thread(void *data)
 static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 {
 	struct io_submit_state state, *statep = NULL;
-	int i, submit = 0;
+	int i, submitted = 0;
 
 	if (to_submit > IO_PLUG_THRESHOLD) {
 		io_submit_state_start(&state, ctx, to_submit);
@@ -2028,12 +2028,11 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 		s.has_user = true;
 		s.needs_lock = false;
 		s.needs_fixed_file = false;
-		submit++;
+		submitted++;
 
 		ret = io_submit_sqe(ctx, &s, statep);
 		if (ret) {
 			io_cqring_add_event(ctx, s.sqe->user_data, ret, 0);
-			break;
 		}
 	}
 	io_commit_sqring(ctx);
@@ -2041,7 +2040,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 	if (statep)
 		io_submit_state_end(statep);
 
-	return submit;
+	return submitted;
 }
 
 static unsigned io_cqring_events(struct io_cq_ring *ring)
@@ -2779,15 +2778,6 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 
 		min_complete = min(min_complete, ctx->cq_entries);
 
-		/*
-		 * The application could have included the 'to_submit' count
-		 * in how many events it wanted to wait for. If we failed to
-		 * submit the desired count, we may need to adjust the number
-		 * of events to poll/wait for.
-		 */
-		if (submitted < to_submit)
-			min_complete = min_t(unsigned, submitted, min_complete);
-
 		if (ctx->flags & IORING_SETUP_IOPOLL) {
 			mutex_lock(&ctx->uring_lock);
 			ret = io_iopoll_check(ctx, &nr_events, min_complete);
-- 
2.20.1

