On 2019/10/9 9:19, Jackie Liu wrote:
__io_get_deferred_req is used to get all defer lists, including defer_list
and timeout_list, but io_sequence_defer should be only cares about the sequence.

Signed-off-by: Jackie Liu <liuyu...@kylinos.cn>
---
  fs/io_uring.c | 13 +++++--------
  1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 8a0381f1a43b..8ec2443eb019 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -418,9 +418,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct 
io_uring_params *p)
  static inline bool io_sequence_defer(struct io_ring_ctx *ctx,
                                     struct io_kiocb *req)
  {
-       /* timeout requests always honor sequence */
-       if (!(req->flags & REQ_F_TIMEOUT) &&
-           (req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
+       if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
                return false;
return req->sequence != ctx->cached_cq_tail + ctx->rings->sq_dropped;
@@ -435,12 +433,11 @@ static struct io_kiocb *__io_get_deferred_req(struct 
io_ring_ctx *ctx,
                return NULL;
req = list_first_entry(list, struct io_kiocb, list);
-       if (!io_sequence_defer(ctx, req)) {
-               list_del_init(&req->list);
-               return req;
-       }
+       if (!(req->flags & REQ_F_TIMEOUT) && io_sequence_defer(ctx, req))
+               return NULL;
Hi,

For timeout req, we should also compare the sequence to determine to return NULL or the req. But now we will return req directly. Actually, no need to compare req->flags with REQ_F_TIMEOUT.

Another problem, before this change, a timeout req can also drain the sqe(io_queue_sqe->io_req_defer and add to refer list), i am not sure is it a right or wrong logic, but your patch fix that.

Thanks,
Kun.
- return NULL;
+       list_del_init(&req->list);
+       return req;
  }
static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)


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