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@chris-wilson.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petri Latvala <petri.latvala@intel.com>
Link: http://lkml.kernel.org/r/151027307351.14762.4611888896020658384@mail.alporthouse.com

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index e2ebe8c71e8fe31fa7d5ec16a74798b40ca41469..6647b33f7eb0bdae240b7fc1c3635d39d817cead 100644 (file)
--- 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.