io_uring: avoid pointless cred reference count bump

req->creds and ctx->sq_creds already hold reference counts that are
stable during the operations.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Jeff Layton <[email protected]>
Reviewed-by: Jens Axboe <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

Author: brauner

io_uring/io_uring.c

@@ -1728,7 +1728,7 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 		return -EBADF;
 
 	if (unlikely((req->flags & REQ_F_CREDS) && req->creds != current_cred()))
-		creds = override_creds(get_new_cred(req->creds));
+		creds = override_creds(req->creds);
 
 	if (!def->audit_skip)
 		audit_uring_entry(req->opcode);
@@ -1739,7 +1739,7 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 		audit_uring_exit(!ret, ret);
 
 	if (creds)
-		put_cred(revert_creds(creds));
+		revert_creds(creds);
 
 	if (ret == IOU_OK) {
 		if (issue_flags & IO_URING_F_COMPLETE_DEFER)

io_uring/sqpoll.c

@@ -174,7 +174,7 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
 		const struct cred *creds = NULL;
 
 		if (ctx->sq_creds != current_cred())
-			creds = override_creds(get_new_cred(ctx->sq_creds));
+			creds = override_creds(ctx->sq_creds);
 
 		mutex_lock(&ctx->uring_lock);
 		if (!wq_list_empty(&ctx->iopoll_list))
@@ -192,7 +192,7 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
 		if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))
 			wake_up(&ctx->sqo_sq_wait);
 		if (creds)
-			put_cred(revert_creds(creds));
+			revert_creds(creds);
 	}
 
 	return ret;