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From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
	io-uring@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Tejun Heo <tj@kernel.org>, Dennis Zhou <dennis@kernel.org>,
	Christoph Lameter <cl@linux.com>
Subject: [PATCH v4 1/2] pcpu_ref: add percpu_ref_tryget_many()
Date: Sat, 28 Dec 2019 14:13:02 +0300
Message-ID: <9db688ebaea49de5e794d082aca351cc278ed2ed.1577528535.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1577528535.git.asml.silence@gmail.com>

Add percpu_ref_tryget_many(), which works the same way as
percpu_ref_tryget(), but grabs specified number of refs.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Dennis Zhou <dennis@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
---
 include/linux/percpu-refcount.h | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 390031e816dc..22d9d183950d 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -210,15 +210,17 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
 }
 
 /**
- * percpu_ref_tryget - try to increment a percpu refcount
+ * percpu_ref_tryget_many - try to increment a percpu refcount
  * @ref: percpu_ref to try-get
+ * @nr: number of references to get
  *
- * Increment a percpu refcount unless its count already reached zero.
+ * Increment a percpu refcount  by @nr unless its count already reached zero.
  * Returns %true on success; %false on failure.
  *
  * This function is safe to call as long as @ref is between init and exit.
  */
-static inline bool percpu_ref_tryget(struct percpu_ref *ref)
+static inline bool percpu_ref_tryget_many(struct percpu_ref *ref,
+					  unsigned long nr)
 {
 	unsigned long __percpu *percpu_count;
 	bool ret;
@@ -226,10 +228,10 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref)
 	rcu_read_lock();
 
 	if (__ref_is_percpu(ref, &percpu_count)) {
-		this_cpu_inc(*percpu_count);
+		this_cpu_add(*percpu_count, nr);
 		ret = true;
 	} else {
-		ret = atomic_long_inc_not_zero(&ref->count);
+		ret = atomic_long_add_unless(&ref->count, nr, 0);
 	}
 
 	rcu_read_unlock();
@@ -237,6 +239,20 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref)
 	return ret;
 }
 
+/**
+ * percpu_ref_tryget - try to increment a percpu refcount
+ * @ref: percpu_ref to try-get
+ *
+ * Increment a percpu refcount unless its count already reached zero.
+ * Returns %true on success; %false on failure.
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline bool percpu_ref_tryget(struct percpu_ref *ref)
+{
+	return percpu_ref_tryget_many(ref, 1);
+}
+
 /**
  * percpu_ref_tryget_live - try to increment a live percpu refcount
  * @ref: percpu_ref to try-get
-- 
2.24.0


  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-17 22:28 [PATCH 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-17 22:28 ` [PATCH 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-17 23:42   ` Jens Axboe
2019-12-18 16:26     ` Tejun Heo
2019-12-18 17:49       ` Dennis Zhou
2019-12-21 15:36         ` Pavel Begunkov
2019-12-17 22:28 ` [PATCH 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-17 23:21   ` Jens Axboe
2019-12-17 23:31     ` Jens Axboe
2019-12-18  9:25       ` Pavel Begunkov
2019-12-18  9:23     ` Pavel Begunkov
2019-12-18  0:02   ` Jens Axboe
2019-12-18 10:41     ` Pavel Begunkov
2019-12-21 16:15   ` [PATCH v2 0/3] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 16:15     ` [PATCH v2 1/3] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 16:15     ` [PATCH v2 2/3] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 16:15     ` [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits Pavel Begunkov
2019-12-21 16:20       ` Pavel Begunkov
2019-12-21 16:38         ` Jens Axboe
2019-12-21 16:48           ` Pavel Begunkov
2019-12-21 17:01             ` Jens Axboe
2019-12-21 17:26               ` Pavel Begunkov
2019-12-21 20:12       ` [PATCH v3 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 20:12         ` [PATCH v3 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 20:12         ` [PATCH v3 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 21:56           ` Pavel Begunkov
2019-12-28 11:13         ` [PATCH v4 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-28 11:13           ` Pavel Begunkov [this message]
2019-12-28 11:13           ` [PATCH v4 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-28 11:15             ` Pavel Begunkov
2019-12-28 17:03               ` Jens Axboe
2019-12-28 18:37                 ` Pavel Begunkov
2019-12-30  3:33                   ` Brian Gianforcaro
2019-12-30 18:45                     ` Pavel Begunkov

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