1 files changed, 33 insertions, 25 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1745ca788ede..6f2545037e57 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -377,7 +377,7 @@ struct workqueue_struct {
 
 	/* hot fields used during command issue, aligned to cacheline */
 	unsigned int		flags ____cacheline_aligned; /* WQ: WQ_* flags */
-	struct pool_workqueue __percpu __rcu **cpu_pwq; /* I: per-cpu pwqs */
+	struct pool_workqueue __rcu * __percpu *cpu_pwq; /* I: per-cpu pwqs */
 	struct wq_node_nr_active *node_nr_active[]; /* I: per-node nr_active */
 };
 
@@ -897,7 +897,7 @@ static struct worker_pool *get_work_pool(struct work_struct *work)
 
 static unsigned long shift_and_mask(unsigned long v, u32 shift, u32 bits)
 {
-	return (v >> shift) & ((1 << bits) - 1);
+	return (v >> shift) & ((1U << bits) - 1);
 }
 
 static void work_offqd_unpack(struct work_offq_data *offqd, unsigned long data)
@@ -2709,7 +2709,6 @@ static void detach_worker(struct worker *worker)
 
 	unbind_worker(worker);
 	list_del(&worker->node);
-	worker->pool = NULL;
 }
 
 /**
@@ -2729,6 +2728,7 @@ static void worker_detach_from_pool(struct worker *worker)
 
 	mutex_lock(&wq_pool_attach_mutex);
 	detach_worker(worker);
+	worker->pool = NULL;
 	mutex_unlock(&wq_pool_attach_mutex);
 
 	/* clear leftover flags without pool->lock after it is detached */
@@ -3349,9 +3349,12 @@ woke_up:
 	if (unlikely(worker->flags & WORKER_DIE)) {
 		raw_spin_unlock_irq(&pool->lock);
 		set_pf_worker(false);
-
+		/*
+		 * The worker is dead and PF_WQ_WORKER is cleared, worker->pool
+		 * shouldn't be accessed, reset it to NULL in case otherwise.
+		 */
+		worker->pool = NULL;
 		ida_free(&pool->worker_ida, worker->id);
-		WARN_ON_ONCE(!list_empty(&worker->entry));
 		return 0;
 	}
 
@@ -4167,7 +4170,6 @@ already_gone:
 static bool __flush_work(struct work_struct *work, bool from_cancel)
 {
 	struct wq_barrier barr;
-	unsigned long data;
 
 	if (WARN_ON(!wq_online))
 		return false;
@@ -4185,29 +4187,35 @@ static bool __flush_work(struct work_struct *work, bool from_cancel)
 	 * was queued on a BH workqueue, we also know that it was running in the
 	 * BH context and thus can be busy-waited.
 	 */
-	data = *work_data_bits(work);
-	if (from_cancel &&
-	    !WARN_ON_ONCE(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_BH)) {
-		/*
-		 * On RT, prevent a live lock when %current preempted soft
-		 * interrupt processing or prevents ksoftirqd from running by
-		 * keeping flipping BH. If the BH work item runs on a different
-		 * CPU then this has no effect other than doing the BH
-		 * disable/enable dance for nothing. This is copied from
-		 * kernel/softirq.c::tasklet_unlock_spin_wait().
-		 */
-		while (!try_wait_for_completion(&barr.done)) {
-			if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
-				local_bh_disable();
-				local_bh_enable();
-			} else {
-				cpu_relax();
+	if (from_cancel) {
+		unsigned long data = *work_data_bits(work);
+
+		if (!WARN_ON_ONCE(data & WORK_STRUCT_PWQ) &&
+		    (data & WORK_OFFQ_BH)) {
+			/*
+			 * On RT, prevent a live lock when %current preempted
+			 * soft interrupt processing or prevents ksoftirqd from
+			 * running by keeping flipping BH. If the BH work item
+			 * runs on a different CPU then this has no effect other
+			 * than doing the BH disable/enable dance for nothing.
+			 * This is copied from
+			 * kernel/softirq.c::tasklet_unlock_spin_wait().
+			 */
+			while (!try_wait_for_completion(&barr.done)) {
+				if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+					local_bh_disable();
+					local_bh_enable();
+				} else {
+					cpu_relax();
+				}
 			}
+			goto out_destroy;
 		}
-	} else {
-		wait_for_completion(&barr.done);
 	}
 
+	wait_for_completion(&barr.done);
+
+out_destroy:
 	destroy_work_on_stack(&barr.work);
 	return true;
 }