linux-kernel - [RFC PATCH v2 1/5] futex: Add futex_set

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Date:   Tue, 20 Sep 2016 09:42:39 -0400
From:   Waiman Long <Waiman.Long@....com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jonathan Corbet <corbet@....net>
Cc:     linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Davidlohr Bueso <dave@...olabs.net>,
        Jason Low <jason.low2@....com>,
        Scott J Norton <scott.norton@....com>,
        Douglas Hatch <doug.hatch@....com>,
        Waiman Long <Waiman.Long@....com>
Subject: [RFC PATCH v2 1/5] futex: Add futex_set_timer() helper function

This patch adds a new futex_set_timer() function to consolidate all
the sleeping hrtime setup code.

Signed-off-by: Waiman Long <Waiman.Long@....com>
---
 kernel/futex.c |   51 ++++++++++++++++++++++++---------------------------
 1 files changed, 24 insertions(+), 27 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 46cb3a3..37e61ef 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -467,6 +467,25 @@ static void drop_futex_key_refs(union futex_key *key)
 	}
 }
 
+/*
+ * Helper function to set the sleeping hrtimer.
+ */
+static inline void futex_set_timer(ktime_t *time, struct hrtimer_sleeper **pto,
+		struct hrtimer_sleeper *timeout, int flags, u64 range_ns)
+{
+	if (!time)
+		return;
+	*pto = timeout;
+	hrtimer_init_on_stack(&timeout->timer, (flags & FLAGS_CLOCKRT) ?
+			      CLOCK_REALTIME : CLOCK_MONOTONIC,
+			      HRTIMER_MODE_ABS);
+	hrtimer_init_sleeper(timeout, current);
+	if (range_ns)
+		hrtimer_set_expires_range_ns(&timeout->timer, *time, range_ns);
+	else
+		hrtimer_set_expires(&timeout->timer, *time);
+}
+
 /**
  * get_futex_key() - Get parameters which are the keys for a futex
  * @uaddr:	virtual address of the futex
@@ -2403,17 +2422,8 @@ static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
 		return -EINVAL;
 	q.bitset = bitset;
 
-	if (abs_time) {
-		to = &timeout;
-
-		hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ?
-				      CLOCK_REALTIME : CLOCK_MONOTONIC,
-				      HRTIMER_MODE_ABS);
-		hrtimer_init_sleeper(to, current);
-		hrtimer_set_expires_range_ns(&to->timer, *abs_time,
-					     current->timer_slack_ns);
-	}
-
+	futex_set_timer(abs_time, &to, &timeout, flags,
+			current->timer_slack_ns);
 retry:
 	/*
 	 * Prepare to wait on uaddr. On success, holds hb lock and increments
@@ -2501,13 +2511,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
 	if (refill_pi_state_cache())
 		return -ENOMEM;
 
-	if (time) {
-		to = &timeout;
-		hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME,
-				      HRTIMER_MODE_ABS);
-		hrtimer_init_sleeper(to, current);
-		hrtimer_set_expires(&to->timer, *time);
-	}
+	futex_set_timer(time, &to, &timeout, FLAGS_CLOCKRT, 0);
 
 retry:
 	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key, VERIFY_WRITE);
@@ -2816,15 +2820,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	if (!bitset)
 		return -EINVAL;
 
-	if (abs_time) {
-		to = &timeout;
-		hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ?
-				      CLOCK_REALTIME : CLOCK_MONOTONIC,
-				      HRTIMER_MODE_ABS);
-		hrtimer_init_sleeper(to, current);
-		hrtimer_set_expires_range_ns(&to->timer, *abs_time,
-					     current->timer_slack_ns);
-	}
+	futex_set_timer(abs_time, &to, &timeout, flags,
+			current->timer_slack_ns);
 
 	/*
 	 * The waiter is allocated on our stack, manipulated by the requeue
-- 
1.7.1