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McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Steven Rostedt , Lai Jiangshan , Zqiang , rcu@vger.kernel.org Subject: [RFC PATCH 3/4] rculist.h: Fix parentheses around macro pointer parameter use Date: Wed, 3 May 2023 21:29:13 -0400 Message-Id: <20230504012914.1797355-3-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230504012914.1797355-1-mathieu.desnoyers@efficios.com> References: <20230504012914.1797355-1-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RDNS_NONE,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1764926092714439470?= X-GMAIL-MSGID: =?utf-8?q?1764926092714439470?= Add missing parentheses around use of macro argument "pos" in those patterns to ensure operator precedence behaves as expected: - typeof(*pos) - pos->member This corrects the following usage pattern where operator precedence is unexpected: LIST_HEAD(testlist); struct test { struct list_head node; int a; }; // pos->member issue void f(void) { struct test *t1; struct test **t2 = &t1; list_for_each_entry_rcu((*t2), &testlist, node) { /* works */ //... } list_for_each_entry_rcu(*t2, &testlist, node) { /* broken */ //... } } 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. Signed-off-by: Mathieu Desnoyers Cc: "Paul E. McKenney" Cc: Andrew Morton Cc: Frederic Weisbecker Cc: Neeraj Upadhyay Cc: Joel Fernandes Cc: Josh Triplett Cc: Boqun Feng Cc: Steven Rostedt Cc: Lai Jiangshan Cc: Zqiang Cc: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Steven Rostedt (Google) --- include/linux/rculist.h | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/include/linux/rculist.h b/include/linux/rculist.h index d29740be4833..d27aeff5447d 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -388,9 +388,9 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, */ #define list_for_each_entry_rcu(pos, head, member, cond...) \ for (__list_check_rcu(dummy, ## cond, 0), \ - pos = list_entry_rcu((head)->next, typeof(*pos), member); \ - &pos->member != (head); \ - pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) + pos = list_entry_rcu((head)->next, typeof(*(pos)), member);\ + &(pos)->member != (head); \ + pos = list_entry_rcu((pos)->member.next, typeof(*(pos)), member)) /** * list_for_each_entry_srcu - iterate over rcu list of given type @@ -407,9 +407,9 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, */ #define list_for_each_entry_srcu(pos, head, member, cond) \ for (__list_check_srcu(cond), \ - pos = list_entry_rcu((head)->next, typeof(*pos), member); \ - &pos->member != (head); \ - pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) + pos = list_entry_rcu((head)->next, typeof(*(pos)), member);\ + &(pos)->member != (head); \ + pos = list_entry_rcu((pos)->member.next, typeof(*(pos)), member)) /** * list_entry_lockless - get the struct for this entry @@ -441,9 +441,9 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, * but never deleted. */ #define list_for_each_entry_lockless(pos, head, member) \ - for (pos = list_entry_lockless((head)->next, typeof(*pos), member); \ - &pos->member != (head); \ - pos = list_entry_lockless(pos->member.next, typeof(*pos), member)) + for (pos = list_entry_lockless((head)->next, typeof(*(pos)), member); \ + &(pos)->member != (head); \ + pos = list_entry_lockless((pos)->member.next, typeof(*(pos)), member)) /** * list_for_each_entry_continue_rcu - continue iteration over list of given type @@ -464,9 +464,9 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, * position. */ #define list_for_each_entry_continue_rcu(pos, head, member) \ - for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \ - &pos->member != (head); \ - pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) + for (pos = list_entry_rcu((pos)->member.next, typeof(*(pos)), member); \ + &(pos)->member != (head); \ + pos = list_entry_rcu((pos)->member.next, typeof(*(pos)), member)) /** * list_for_each_entry_from_rcu - iterate over a list from current point @@ -486,8 +486,8 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, * after the given position. */ #define list_for_each_entry_from_rcu(pos, head, member) \ - for (; &(pos)->member != (head); \ - pos = list_entry_rcu(pos->member.next, typeof(*(pos)), member)) + for (; &(pos)->member != (head); \ + pos = list_entry_rcu((pos)->member.next, typeof(*(pos)), member)) /** * hlist_del_rcu - deletes entry from hash list without re-initialization