[PATCH] xen-blkback: Use freezable wait_event variants for freezable kthread

[Kevin Hao <haokexin@xxxxxxxxx>]

A freezable kernel thread can enter frozen state during freezing by
either calling try_to_freeze() or using wait_event_freezable() and its
variants. So for the following snippet of code in a kernel thread loop:
  try_to_freeze();
  wait_event_interruptible();

We can change it to a simple wait_event_freezable() and then eliminate
a function call.

Signed-off-by: Kevin Hao <haokexin@xxxxxxxxx>
---
 drivers/block/xen-blkback/blkback.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/block/xen-blkback/blkback.c 
b/drivers/block/xen-blkback/blkback.c
index 4defd7f387c7..bef0f950b257 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -563,20 +563,18 @@ int xen_blkif_schedule(void *arg)
 
        set_freezable();
        while (!kthread_should_stop()) {
-               if (try_to_freeze())
-                       continue;
                if (unlikely(vbd->size != vbd_sz(vbd)))
                        xen_vbd_resize(blkif);
 
                timeout = msecs_to_jiffies(LRU_INTERVAL);
 
-               timeout = wait_event_interruptible_timeout(
+               timeout = wait_event_freezable_timeout(
                        ring->wq,
                        ring->waiting_reqs || kthread_should_stop(),
                        timeout);
                if (timeout == 0)
                        goto purge_gnt_list;
-               timeout = wait_event_interruptible_timeout(
+               timeout = wait_event_freezable_timeout(
                        ring->pending_free_wq,
                        !list_empty(&ring->pending_free) ||
                        kthread_should_stop(),
@@ -593,8 +591,8 @@ int xen_blkif_schedule(void *arg)
                if (ret > 0)
                        ring->waiting_reqs = 1;
                if (ret == -EACCES)
-                       wait_event_interruptible(ring->shutdown_wq,
-                                                kthread_should_stop());
+                       wait_event_freezable(ring->shutdown_wq,
+                                            kthread_should_stop());
 
                if (do_eoi && !ring->waiting_reqs) {
                        xen_irq_lateeoi(ring->irq, eoi_flags);
-- 
2.39.2