82 lines
2.5 KiB
Diff
82 lines
2.5 KiB
Diff
From 39f710e222c6e981f751df63b84ecb82b67940d0 Mon Sep 17 00:00:00 2001
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From: Peter Zijlstra <peterz@infradead.org>
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Date: Wed, 22 Mar 2017 11:35:53 +0100
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Subject: [PATCH 010/365] futex: Cleanup refcounting
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Upstream commit bf92cf3a5100f5a0d5f9834787b130159397cb22
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Add a put_pit_state() as counterpart for get_pi_state() so the refcounting
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becomes consistent.
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Cc: juri.lelli@arm.com
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Cc: bigeasy@linutronix.de
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Cc: xlpang@redhat.com
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Cc: rostedt@goodmis.org
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Cc: mathieu.desnoyers@efficios.com
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Cc: jdesfossez@efficios.com
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Cc: dvhart@infradead.org
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Cc: bristot@redhat.com
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Link: http://lkml.kernel.org/r/20170322104151.801778516@infradead.org
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/futex.c | 13 +++++++++----
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1 file changed, 9 insertions(+), 4 deletions(-)
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diff --git a/kernel/futex.c b/kernel/futex.c
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index c0d5e64b37b2..629db2cd530e 100644
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--- a/kernel/futex.c
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+++ b/kernel/futex.c
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@@ -818,7 +818,7 @@ static int refill_pi_state_cache(void)
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return 0;
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}
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-static struct futex_pi_state * alloc_pi_state(void)
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+static struct futex_pi_state *alloc_pi_state(void)
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{
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struct futex_pi_state *pi_state = current->pi_state_cache;
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@@ -828,6 +828,11 @@ static struct futex_pi_state * alloc_pi_state(void)
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return pi_state;
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}
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+static void get_pi_state(struct futex_pi_state *pi_state)
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+{
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+ WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount));
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+}
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+
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/*
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* Drops a reference to the pi_state object and frees or caches it
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* when the last reference is gone.
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@@ -872,7 +877,7 @@ static void put_pi_state(struct futex_pi_state *pi_state)
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* Look up the task based on what TID userspace gave us.
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* We dont trust it.
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*/
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-static struct task_struct * futex_find_get_task(pid_t pid)
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+static struct task_struct *futex_find_get_task(pid_t pid)
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{
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struct task_struct *p;
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@@ -1119,7 +1124,7 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval,
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goto out_einval;
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out_attach:
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- atomic_inc(&pi_state->refcount);
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+ get_pi_state(pi_state);
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raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
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*ps = pi_state;
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return 0;
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@@ -2056,7 +2061,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
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* refcount on the pi_state and store the pointer in
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* the futex_q object of the waiter.
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*/
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- atomic_inc(&pi_state->refcount);
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+ get_pi_state(pi_state);
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this->pi_state = pi_state;
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ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex,
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this->rt_waiter,
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--
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2.28.0
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