[RFC PATCH 08/13] net: dsa: 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 08/13] net: dsa: future proof usage of list iterator after the loop
Date: Thu, 17 Feb 2022 19:48:24 +0100	[thread overview]
Message-ID: <20220217184829.1991035-9-jakobkoschel@gmail.com> (raw)
In-Reply-To: <20220217184829.1991035-1-jakobkoschel@gmail.com>

With the speculative safe version of the list iterator p will be NULL if
the terminating condition was hit and needs to be reset to p derived
from the head, before using p->list.

Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
 drivers/net/dsa/sja1105/sja1105_vl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c
index f5dca6a9b0f9..a4f2b95b09c4 100644
--- a/drivers/net/dsa/sja1105/sja1105_vl.c
+++ b/drivers/net/dsa/sja1105/sja1105_vl.c
@@ -40,6 +40,8 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
 			if (e->interval < p->interval)
 				break;
 		}
+		if (!p)
+			p = list_entry(p, &gating_cfg->entries, list);
 		list_add(&e->list, p->list.prev);
 	}
 
-- 
2.25.1

