[RFC PATCH 09/13] drbd: future proof usage of list iterator after the loop

From: Jakob Koschel <jakobkoschel@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Arnd Bergman <arnd@arndb.de>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Mike Rapoport <rppt@kernel.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Brian Johannesmeyer <bjohannesmeyer@gmail.com>,
	Cristiano Giuffrida <c.giuffrida@vu.nl>,
	"Bos, H.J." <h.j.bos@vu.nl>,
	Jakob Koschel <jakobkoschel@gmail.com>
Subject: [RFC PATCH 09/13] drbd: future proof usage of list iterator after the loop
Date: Thu, 17 Feb 2022 19:48:25 +0100	[thread overview]
Message-ID: <20220217184829.1991035-10-jakobkoschel@gmail.com> (raw)
In-Reply-To: <20220217184829.1991035-1-jakobkoschel@gmail.com>

With the speculative safe version of the list iterator req will be NULL
if the terminating condition was hit and needs to be reset to req
derived from the head, before calling list_for_each_entry_safe_from().

Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
 drivers/block/drbd/drbd_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 6f450816c4fa..d98205b46f59 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -227,6 +227,8 @@ void tl_release(struct drbd_connection *connection, unsigned int barrier_nr,
 	list_for_each_entry(req, &connection->transfer_log, tl_requests)
 		if (req->epoch == expect_epoch)
 			break;
+	if (!req)
+		req = list_entry(req, &connection->transfer_log, tl_requests);
 	list_for_each_entry_safe_from(req, r, &connection->transfer_log, tl_requests) {
 		if (req->epoch != expect_epoch)
 			break;
-- 
2.25.1

