Merge branch 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull two workqueue fixes from Tejun Heo:
 "A lockdep notation update so that nested work_on_cpu() invocations
  don't lead to spurious lockdep warnings and fix for an unbound attr
  bug which made what's shown in sysfs deviate from the actual ones.
  Both patches have pretty limited scope"

* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: copy workqueue_attrs with all fields
  workqueue: allow work_on_cpu() to be called recursively

1 files changed, 34 insertions, 10 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 0b72e816b8d0..7f5d4be22034 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2817,6 +2817,19 @@ already_gone:
         return false;
 }
 
+static bool __flush_work(struct work_struct *work)
+{
+        struct wq_barrier barr;
+
+        if (start_flush_work(work, &barr)) {
+                wait_for_completion(&barr.done);
+                destroy_work_on_stack(&barr.work);
+                return true;
+        } else {
+                return false;
+        }
+}
+
 /**
  * flush_work - wait for a work to finish executing the last queueing instance
  * @work: the work to flush
@@ -2830,18 +2843,10 @@ already_gone:
  */
 bool flush_work(struct work_struct *work)
 {
-        struct wq_barrier barr;
-
         lock_map_acquire(&work->lockdep_map);
         lock_map_release(&work->lockdep_map);
 
-        if (start_flush_work(work, &barr)) {
-                wait_for_completion(&barr.done);
-                destroy_work_on_stack(&barr.work);
-                return true;
-        } else {
-                return false;
-        }
+        return __flush_work(work);
 }
 EXPORT_SYMBOL_GPL(flush_work);
 
@@ -3411,6 +3416,12 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to,
 {
         to->nice = from->nice;
         cpumask_copy(to->cpumask, from->cpumask);
+        /*
+         * Unlike hash and equality test, this function doesn't ignore
+         * ->no_numa as it is used for both pool and wq attrs.  Instead,
+         * get_unbound_pool() explicitly clears ->no_numa after copying.
+         */
+        to->no_numa = from->no_numa;
 }
 
 /* hash value of the content of @attr */
@@ -3578,6 +3589,12 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
         lockdep_set_subclass(&pool->lock, 1);   /* see put_pwq() */
         copy_workqueue_attrs(pool->attrs, attrs);
 
+        /*
+         * no_numa isn't a worker_pool attribute, always clear it.  See
+         * 'struct workqueue_attrs' comments for detail.
+         */
+        pool->attrs->no_numa = false;
+
         /* if cpumask is contained inside a NUMA node, we belong to that node */
         if (wq_numa_enabled) {
                 for_each_node(node) {
@@ -4756,7 +4773,14 @@ long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 
         INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
         schedule_work_on(cpu, &wfc.work);
-        flush_work(&wfc.work);
+
+        /*
+         * The work item is on-stack and can't lead to deadlock through
+         * flushing.  Use __flush_work() to avoid spurious lockdep warnings
+         * when work_on_cpu()s are nested.
+         */
+        __flush_work(&wfc.work);
+
         return wfc.ret;
 }
 EXPORT_SYMBOL_GPL(work_on_cpu);