[PATCH AUTOSEL 5.3 178/203] io_uring: fix wrong sequence setting logic

Sasha Levin
2019-09-22T19:31:49Z

From: Jackie Liu <liuyun01@kylinos.cn>

[ Upstream commit 8776f3fa15a5cd213c4dfab7ddaf557983374ea6 ]

Sqo_thread will get sqring in batches, which will cause
ctx->cached_sq_head to be added in batches. if one of these
sqes is set with the DRAIN flag, then he will never get a
chance to process, and finally sqo_thread will not exit.

Fixes: de0617e4671 ("io_uring: add support for marking commands as draining")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/io_uring.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index cfb48bd088e12..06d048341fa41 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -288,6 +288,7 @@ struct io_ring_ctx {
struct sqe_submit {
const struct io_uring_sqe *sqe;
unsigned short index;
+ u32 sequence;
bool has_user;
bool needs_lock;
bool needs_fixed_file;
@@ -2040,7 +2041,7 @@ static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,

if (flags & IOSQE_IO_DRAIN) {
req->flags |= REQ_F_IO_DRAIN;
- req->sequence = ctx->cached_sq_head - 1;
+ req->sequence = s->sequence;
}

if (!io_op_needs_file(s->sqe))
@@ -2247,6 +2248,7 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
if (head < ctx->sq_entries) {
s->index = head;
s->sqe = &ctx->sq_sqes[head];
+ s->sequence = ctx->cached_sq_head;
ctx->cached_sq_head++;
return true;
}
--
2.20.1