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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2014-06-18 22:33:51 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2014-06-18 22:33:51 -0300
commit6d520f15b746e85b26358ec77e11524f8b4a2224 (patch)
treededab09e8e12a9129251c22d17a513cb176b3114 /kernels/linux-libre-pae/0008-futex-avoid-race-between-requeue-and-wake.patch
parentf69f9e4ba8e14a329efc2cf72ae254e781e9bf37 (diff)
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linux-libre-{pae,xen}-3.15.1-1: updating version
* readd dell_rbu module * remove not needed patches * #40818 (https://bugs.archlinux.org/task/40818) disable CONFIG_MEMCG_KMEM * #40773 (https://bugs.archlinux.org/task/40773) disable not needed OTG drivers * #40759 (https://bugs.archlinux.org/task/40759) add ROMFS kernel module * #40845 (https://bugs.archlinux.org/task/40845) add vivi v4l2 modules
Diffstat (limited to 'kernels/linux-libre-pae/0008-futex-avoid-race-between-requeue-and-wake.patch')
-rw-r--r--kernels/linux-libre-pae/0008-futex-avoid-race-between-requeue-and-wake.patch94
1 files changed, 0 insertions, 94 deletions
diff --git a/kernels/linux-libre-pae/0008-futex-avoid-race-between-requeue-and-wake.patch b/kernels/linux-libre-pae/0008-futex-avoid-race-between-requeue-and-wake.patch
deleted file mode 100644
index 8685e1168..000000000
--- a/kernels/linux-libre-pae/0008-futex-avoid-race-between-requeue-and-wake.patch
+++ /dev/null
@@ -1,94 +0,0 @@
-From aafcd8f8692fb9e389608c1efad2e57c0bbb9362 Mon Sep 17 00:00:00 2001
-From: Linus Torvalds <torvalds@linux-foundation.org>
-Date: Tue, 8 Apr 2014 15:30:07 -0700
-Subject: [PATCH 08/10] futex: avoid race between requeue and wake
-
-commit 69cd9eba38867a493a043bb13eb9b33cad5f1a9a upstream.
-
-Jan Stancek reported:
- "pthread_cond_broadcast/4-1.c testcase from openposix testsuite (LTP)
- occasionally fails, because some threads fail to wake up.
-
- Testcase creates 5 threads, which are all waiting on same condition.
- Main thread then calls pthread_cond_broadcast() without holding mutex,
- which calls:
-
- futex(uaddr1, FUTEX_CMP_REQUEUE_PRIVATE, 1, 2147483647, uaddr2, ..)
-
- This immediately wakes up single thread A, which unlocks mutex and
- tries to wake up another thread:
-
- futex(uaddr2, FUTEX_WAKE_PRIVATE, 1)
-
- If thread A manages to call futex_wake() before any waiters are
- requeued for uaddr2, no other thread is woken up"
-
-The ordering constraints for the hash bucket waiter counting are that
-the waiter counts have to be incremented _before_ getting the spinlock
-(because the spinlock acts as part of the memory barrier), but the
-"requeue" operation didn't honor those rules, and nobody had even
-thought about that case.
-
-This fairly simple patch just increments the waiter count for the target
-hash bucket (hb2) when requeing a futex before taking the locks. It
-then decrements them again after releasing the lock - the code that
-actually moves the futex(es) between hash buckets will do the additional
-required waiter count housekeeping.
-
-Reported-and-tested-by: Jan Stancek <jstancek@redhat.com>
-Acked-by: Davidlohr Bueso <davidlohr@hp.com>
-Cc: Peter Zijlstra <peterz@infradead.org>
-Cc: Thomas Gleixner <tglx@linutronix.de>
-Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- kernel/futex.c | 5 +++++
- 1 file changed, 5 insertions(+)
-
-diff --git a/kernel/futex.c b/kernel/futex.c
-index 08ec814..16b1f2c 100644
---- a/kernel/futex.c
-+++ b/kernel/futex.c
-@@ -1450,6 +1450,7 @@ retry:
- hb2 = hash_futex(&key2);
-
- retry_private:
-+ hb_waiters_inc(hb2);
- double_lock_hb(hb1, hb2);
-
- if (likely(cmpval != NULL)) {
-@@ -1459,6 +1460,7 @@ retry_private:
-
- if (unlikely(ret)) {
- double_unlock_hb(hb1, hb2);
-+ hb_waiters_dec(hb2);
-
- ret = get_user(curval, uaddr1);
- if (ret)
-@@ -1508,6 +1510,7 @@ retry_private:
- break;
- case -EFAULT:
- double_unlock_hb(hb1, hb2);
-+ hb_waiters_dec(hb2);
- put_futex_key(&key2);
- put_futex_key(&key1);
- ret = fault_in_user_writeable(uaddr2);
-@@ -1517,6 +1520,7 @@ retry_private:
- case -EAGAIN:
- /* The owner was exiting, try again. */
- double_unlock_hb(hb1, hb2);
-+ hb_waiters_dec(hb2);
- put_futex_key(&key2);
- put_futex_key(&key1);
- cond_resched();
-@@ -1592,6 +1596,7 @@ retry_private:
-
- out_unlock:
- double_unlock_hb(hb1, hb2);
-+ hb_waiters_dec(hb2);
-
- /*
- * drop_futex_key_refs() must be called outside the spinlocks. During
---
-1.9.2
-