Merge tag 'linux-kselftest-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel...

[linux.git] / kernel / irq_work.c

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index df0dbf4d859b46eea8cdee40bbc05182f6f6b19f..828cc30774bc4d76f498503b083dad428dbf0baa 100644 (file)
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -29,24 +29,16 @@ static DEFINE_PER_CPU(struct llist_head, lazy_list);
  */
 static bool irq_work_claim(struct irq_work *work)
 {
-       int flags, oflags, nflags;
+       int oflags;
 
+       oflags = atomic_fetch_or(IRQ_WORK_CLAIMED, &work->flags);
        /*
-        * Start with our best wish as a premise but only trust any
-        * flag value after cmpxchg() result.
+        * If the work is already pending, no need to raise the IPI.
+        * The pairing atomic_fetch_andnot() in irq_work_run() makes sure
+        * everything we did before is visible.
         */
-       flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING;
-       for (;;) {
-               nflags = flags | IRQ_WORK_CLAIMED;
-               oflags = atomic_cmpxchg(&work->flags, flags, nflags);
-               if (oflags == flags)
-                       break;
-               if (oflags & IRQ_WORK_PENDING)
-                       return false;
-               flags = oflags;
-               cpu_relax();
-       }
-
+       if (oflags & IRQ_WORK_PENDING)
+               return false;
        return true;
 }
 
@@ -143,7 +135,6 @@ static void irq_work_run_list(struct llist_head *list)
 {
        struct irq_work *work, *tmp;
        struct llist_node *llnode;
-       int flags;
 
        BUG_ON(!irqs_disabled());
 
@@ -152,6 +143,7 @@ static void irq_work_run_list(struct llist_head *list)
 
        llnode = llist_del_all(list);
        llist_for_each_entry_safe(work, tmp, llnode, llnode) {
+               int flags;
                /*
                 * Clear the PENDING bit, after this point the @work
                 * can be re-used.
@@ -159,14 +151,14 @@ static void irq_work_run_list(struct llist_head *list)
                 * to claim that work don't rely on us to handle their data
                 * while we are in the middle of the func.
                 */
-               flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING;
-               atomic_xchg(&work->flags, flags);
+               flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
 
                work->func(work);
                /*
                 * Clear the BUSY bit and return to the free state if
                 * no-one else claimed it meanwhile.
                 */
+               flags &= ~IRQ_WORK_PENDING;
                (void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
        }
 }