linux-kernel - [tip:irq/core] irq/work: Use llist_for_each_entry

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Date:   Sun, 12 Nov 2017 04:24:15 -0800
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, petri.latvala@...el.com,
        linux-kernel@...r.kernel.org, byungchul.park@....com,
        tglx@...utronix.de, frederic@...nel.org, peterz@...radead.org,
        mingo@...nel.org
Subject: [tip:irq/core] irq/work: Use llist_for_each_entry_safe

Commit-ID:  d00a08cf9ee986ad6689ce8c6fd176aff679c106
Gitweb:     https://git.kernel.org/tip/d00a08cf9ee986ad6689ce8c6fd176aff679c106
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Sun, 12 Nov 2017 13:02:51 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Sun, 12 Nov 2017 13:15:14 +0100

irq/work: Use llist_for_each_entry_safe

The llist_for_each_entry() loop in irq_work_run_list() is unsafe because
once the works PENDING bit is cleared it can be requeued on another CPU.

Use llist_for_each_entry_safe() instead.

Fixes: 16c0890dc66d ("irq/work: Don't reinvent the wheel but use existing llist API")
Reported-by:Chris Wilson <chris@...is-wilson.co.uk>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Frederic Weisbecker <frederic@...nel.org>
Cc: Byungchul Park <byungchul.park@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Petri Latvala <petri.latvala@...el.com>
Link: http://lkml.kernel.org/r/151027307351.14762.4611888896020658384@mail.alporthouse.com
---
 kernel/irq_work.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index e2ebe8c..6647b33f 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -128,9 +128,9 @@ bool irq_work_needs_cpu(void)
 
 static void irq_work_run_list(struct llist_head *list)
 {
-	unsigned long flags;
-	struct irq_work *work;
+	struct irq_work *work, *tmp;
 	struct llist_node *llnode;
+	unsigned long flags;
 
 	BUG_ON(!irqs_disabled());
 
@@ -138,7 +138,7 @@ static void irq_work_run_list(struct llist_head *list)
 		return;
 
 	llnode = llist_del_all(list);
-	llist_for_each_entry(work, llnode, llnode) {
+	llist_for_each_entry_safe(work, tmp, llnode, llnode) {
 		/*
 		 * Clear the PENDING bit, after this point the @work
 		 * can be re-used.