io_uring: consolidate CQ nr events calculation

Add a helper which calculates number of events in CQ. Handcoded version
of it in io_cqring_overflow_flush() is not the clearest thing, so it
makes it slightly more readable.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index fa3cf56..56ce97f 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1693,6 +1693,11 @@ static inline bool io_should_trigger_evfd(struct io_ring_ctx *ctx)
        return io_wq_current_is_worker();
 }
 
+static inline unsigned __io_cqring_events(struct io_ring_ctx *ctx)
+{
+       return ctx->cached_cq_tail - READ_ONCE(ctx->rings->cq.head);
+}
+
 static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
 {
        if (waitqueue_active(&ctx->wait))
@@ -1723,14 +1728,10 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
        unsigned long flags;
        LIST_HEAD(list);
 
-       if (!force) {
-               if ((ctx->cached_cq_tail - READ_ONCE(rings->cq.head) ==
-                   rings->cq_ring_entries))
-                       return false;
-       }
+       if (!force && __io_cqring_events(ctx) == rings->cq_ring_entries)
+               return false;
 
        spin_lock_irqsave(&ctx->completion_lock, flags);
-
        cqe = NULL;
        list_for_each_entry_safe(req, tmp, &ctx->cq_overflow_list, compl.list) {
                if (!io_match_task(req, tsk, files))
@@ -2314,8 +2315,6 @@ static void io_double_put_req(struct io_kiocb *req)
 
 static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
 {
-       struct io_rings *rings = ctx->rings;
-
        if (test_bit(0, &ctx->cq_check_overflow)) {
                /*
                 * noflush == true is from the waitqueue handler, just ensure
@@ -2330,7 +2329,7 @@ static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
 
        /* See comment at the top of this file */
        smp_rmb();
-       return ctx->cached_cq_tail - READ_ONCE(rings->cq.head);
+       return __io_cqring_events(ctx);
 }
 
 static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)