linux-kernel - [PATCH 8/8] fs/aio: Use rcu_work instead of explicit rcu and work item

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Date:   Wed, 14 Mar 2018 12:45:15 -0700
From:   Tejun Heo <tj@...nel.org>
To:     torvalds@...ux-foundation.org, jannh@...gle.com,
        paulmck@...ux.vnet.ibm.com, bcrl@...ck.org,
        viro@...iv.linux.org.uk, kent.overstreet@...il.com
Cc:     security@...nel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com, Tejun Heo <tj@...nel.org>
Subject: [PATCH 8/8] fs/aio: Use rcu_work instead of explicit rcu and work item

Workqueue now has rcu_work.  Use it instead of open-coding rcu -> work
item bouncing.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
Hello,

If there's no objection, I'll route this together with rcu_work patch
through wq/for-4.17.

Thanks.

 fs/aio.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 6bcd3fb..88d7927 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -115,8 +115,7 @@ struct kioctx {
 	struct page		**ring_pages;
 	long			nr_pages;
 
-	struct rcu_head		free_rcu;
-	struct work_struct	free_work;	/* see free_ioctx() */
+	struct rcu_work		free_rwork;	/* see free_ioctx() */
 
 	/*
 	 * signals when all in-flight requests are done
@@ -592,13 +591,12 @@ static int kiocb_cancel(struct aio_kiocb *kiocb)
 /*
  * free_ioctx() should be RCU delayed to synchronize against the RCU
  * protected lookup_ioctx() and also needs process context to call
- * aio_free_ring(), so the double bouncing through kioctx->free_rcu and
- * ->free_work.
+ * aio_free_ring().  Use rcu_work.
  */
 static void free_ioctx(struct work_struct *work)
 {
-	struct kioctx *ctx = container_of(work, struct kioctx, free_work);
-
+	struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
+					  free_rwork);
 	pr_debug("freeing %p\n", ctx);
 
 	aio_free_ring(ctx);
@@ -608,14 +606,6 @@ static void free_ioctx(struct work_struct *work)
 	kmem_cache_free(kioctx_cachep, ctx);
 }
 
-static void free_ioctx_rcufn(struct rcu_head *head)
-{
-	struct kioctx *ctx = container_of(head, struct kioctx, free_rcu);
-
-	INIT_WORK(&ctx->free_work, free_ioctx);
-	schedule_work(&ctx->free_work);
-}
-
 static void free_ioctx_reqs(struct percpu_ref *ref)
 {
 	struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
@@ -625,7 +615,8 @@ static void free_ioctx_reqs(struct percpu_ref *ref)
 		complete(&ctx->rq_wait->comp);
 
 	/* Synchronize against RCU protected table->table[] dereferences */
-	call_rcu(&ctx->free_rcu, free_ioctx_rcufn);
+	INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
+	queue_rcu_work(system_wq, &ctx->free_rwork);
 }
 
 /*
-- 
2.9.5