Revert "[Backport] io_uring: don't keep looping for more events if we can't flush overflow"

Offering: HULK
hulk inclusion
category: feature
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6BTWC

-------------------------------

This reverts commit f7dc15c2.

We need to apply patch 788d0824269bef (io_uring: import 5.15-stable
io_uring) to move io_uring to separate directory and solve
the problem of CVE-2023-0240.
This patch can be reverted since patch 788d0824269bef contains it.
Signed-off-by: NLi Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: NZhang Yi <yi.zhang@huawei.com>
Reviewed-by: NWang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

fs/io_uring.c

@@ -1718,22 +1718,18 @@ static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
 	return cqe != NULL;
 }
 
-static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
+static void io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
 				     struct task_struct *tsk,
 				     struct files_struct *files)
 {
-	bool ret = true;
-
 	if (test_bit(0, &ctx->cq_check_overflow)) {
 		/* iopoll syncs against uring_lock, not completion_lock */
 		if (ctx->flags & IORING_SETUP_IOPOLL)
 			mutex_lock(&ctx->uring_lock);
-		ret = __io_cqring_overflow_flush(ctx, force, tsk, files);
+		__io_cqring_overflow_flush(ctx, force, tsk, files);
 		if (ctx->flags & IORING_SETUP_IOPOLL)
 			mutex_unlock(&ctx->uring_lock);
 	}
-
-	return ret;
 }
 
 static void __io_cqring_fill_event(struct io_kiocb *req, long res,
@@ -7035,11 +7031,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 	iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
 	trace_io_uring_cqring_wait(ctx, min_events);
 	do {
-		/* if we can't even flush overflow, don't wait for more */
-		if (!io_cqring_overflow_flush(ctx, false, NULL, NULL)) {
-			ret = -EBUSY;
-			break;
-		}
+		io_cqring_overflow_flush(ctx, false, NULL, NULL);
 		prepare_to_wait_exclusive(&ctx->wait, &iowq.wq,
 						TASK_INTERRUPTIBLE);
 		/* make sure we run task_work before checking for signals */