io_uring: cap io_sqring_entries() at SQ ring size

We already do this manually for the !SQPOLL case, do it in general and
we can also dump the ugly min3() in io_submit_sqes().

Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -2434,7 +2434,7 @@ int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
 	if (unlikely(!entries))
 		return 0;
 	/* make sure SQ entry isn't read before tail */
-	ret = left = min3(nr, ctx->sq_entries, entries);
+	ret = left = min(nr, entries);
 	io_get_task_refs(left);
 	io_submit_state_start(&ctx->submit_state, left);
 

io_uring/io_uring.h

@@ -262,9 +262,11 @@ static inline bool io_sqring_full(struct io_ring_ctx *ctx)
 static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
 {
 	struct io_rings *rings = ctx->rings;
+	unsigned int entries;
 
 	/* make sure SQ entry isn't read before tail */
-	return smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
+	entries = smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
+	return min(entries, ctx->sq_entries);
 }
 
 static inline int io_run_task_work(void)