linux-kernel - [RFC PATCH 4/4] llist.h: Fix parentheses around macro pointer parameter use

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Date:   Wed,  3 May 2023 21:29:14 -0400
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Huang Ying <ying.huang@...el.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [RFC PATCH 4/4] llist.h: Fix parentheses around macro pointer parameter use

Add missing parentheses around use of macro argument "pos" in those
patterns to ensure operator precedence behaves as expected:

- typeof(*pos)
- pos->member

The typeof(*pos) lack of parentheses around "pos" is not an issue per se
in the specific macros modified here because "pos" is used as an lvalue,
which should prevent use of any operator causing issue. Still add the
extra parentheses for consistency.

Remove useless parentheses around use of macro parameter (node) in the
following pattern:

  llist_entry((node), typeof(*pos), member)

Because comma is the lowest priority operator already, so the extra pair
of parentheses is redundant.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Huang Ying <ying.huang@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>
---
 include/linux/llist.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/llist.h b/include/linux/llist.h
index 85bda2d02d65..45d358c15d0d 100644
--- a/include/linux/llist.h
+++ b/include/linux/llist.h
@@ -173,9 +173,9 @@ static inline void init_llist_head(struct llist_head *list)
  * reverse the order by yourself before traversing.
  */
 #define llist_for_each_entry_safe(pos, n, node, member)			       \
-	for (pos = llist_entry((node), typeof(*pos), member);		       \
+	for (pos = llist_entry(node, typeof(*(pos)), member);		       \
 	     member_address_is_nonnull(pos, member) &&			       \
-	        (n = llist_entry(pos->member.next, typeof(*n), member), true); \
+		(n = llist_entry((pos)->member.next, typeof(*(n)), member), true); \
 	     pos = n)
 
 /**
-- 
2.25.1