linux-kernel - [PATCH 3/4] md: initialize percpu refcounters using PERCU_REF_ALLOW

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Message-ID: <20190507170150.64051-3-guro@fb.com>
Date:   Tue, 7 May 2019 10:01:49 -0700
From:   Roman Gushchin <guro@...com>
To:     Tejun Heo <tj@...nel.org>
CC:     Jens Axboe <axboe@...nel.dk>, Song Liu <songliubraving@...com>,
        Dennis Zhou <dennis@...nel.org>,
        <linux-kernel@...r.kernel.org>, <kernel-team@...com>,
        Roman Gushchin <guro@...com>
Subject: [PATCH 3/4] md: initialize percpu refcounters using PERCU_REF_ALLOW_REINIT

Percpu reference counters should now be initialized with the
PERCPU_REF_ALLOW_REINIT in order to allow switching them to the
percpu mode from the atomic mode.
To make percpu_ref_switch_to_percpu() call in set_in_sync()
succeed,let's initialize percpu refcounters with the
PERCU_REF_ALLOW_REINIT flag.

Signed-off-by: Roman Gushchin <guro@...com>
---
 drivers/md/md.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 45ffa23fa85d..6b60211d0b3e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5245,7 +5245,8 @@ int mddev_init_writes_pending(struct mddev *mddev)
 {
 	if (mddev->writes_pending.percpu_count_ptr)
 		return 0;
-	if (percpu_ref_init(&mddev->writes_pending, no_op, 0, GFP_KERNEL) < 0)
+	if (percpu_ref_init(&mddev->writes_pending, no_op,
+			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL) < 0)
 		return -ENOMEM;
 	/* We want to start with the refcount at zero */
 	percpu_ref_put(&mddev->writes_pending);
-- 
2.20.1