io_uring: set -EINTR directly when a signal wakes up in io_cqring_wait

We didn't use -ERESTARTSYS to tell the application layer to restart the
system call, but instead return -EINTR. we can set -EINTR directly when
wakeup by the signal, which can help us save an assignment operation and
comparison operation.

Reviewed-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 76d6530..a520c42 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2976,7 +2976,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
                .to_wait        = min_events,
        };
        struct io_rings *rings = ctx->rings;
-       int ret;
+       int ret = 0;
 
        if (io_cqring_events(rings) >= min_events)
                return 0;
@@ -2994,7 +2994,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
                        return ret;
        }
 
-       ret = 0;
        iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
        trace_io_uring_cqring_wait(ctx, min_events);
        do {
@@ -3004,15 +3003,13 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
                        break;
                schedule();
                if (signal_pending(current)) {
-                       ret = -ERESTARTSYS;
+                       ret = -EINTR;
                        break;
                }
        } while (1);
        finish_wait(&ctx->wait, &iowq.wq);
 
-       restore_saved_sigmask_unless(ret == -ERESTARTSYS);
-       if (ret == -ERESTARTSYS)
-               ret = -EINTR;
+       restore_saved_sigmask_unless(ret == -EINTR);
 
        return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
 }