linux-kernel - [PATCH 2/4] io_uring: initialize percpu refcounters using PERCU_REF_ALLOW

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Message-ID: <20190507170150.64051-2-guro@fb.com>
Date:   Tue, 7 May 2019 10:01:48 -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 2/4] io_uring: 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. This is exactly what
percpu_ref_reinit() called from __io_uring_register() is supposed to
do. So let's initialize percpu refcounters with the
PERCU_REF_ALLOW_REINIT flag.

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

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 452e35357865..9a9df175af31 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -397,7 +397,8 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	if (!ctx)
 		return NULL;
 
-	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free, 0, GFP_KERNEL)) {
+	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
+			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
 		kfree(ctx);
 		return NULL;
 	}
-- 
2.20.1