This is a note to let you know that I've just added the patch titled
ipc/util.c, ipc_rcu_alloc: cacheline align allocation
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipc-util.c-ipc_rcu_alloc-cacheline-align-allocation.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 196aa0132fc7261f34b10ae1bfb44abc1bc69b3c Mon Sep 17 00:00:00 2001
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Date: Mon, 8 Jul 2013 16:01:20 -0700
Subject: ipc/util.c, ipc_rcu_alloc: cacheline align allocation
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
commit 196aa0132fc7261f34b10ae1bfb44abc1bc69b3c upstream.
Enforce that ipc_rcu_alloc returns a cacheline aligned pointer on SMP.
Rationale:
The SysV sem code tries to move the main spinlock into a seperate
cacheline (____cacheline_aligned_in_smp). This works only if
ipc_rcu_alloc returns cacheline aligned pointers. vmalloc and kmalloc
return cacheline algined pointers, the implementation of ipc_rcu_alloc
breaks that.
[akpm@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
ipc/util.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -468,9 +468,7 @@ void ipc_free(void* ptr, int size)
struct ipc_rcu {
struct rcu_head rcu;
atomic_t refcount;
- /* "void *" makes sure alignment of following data is sane. */
- void *data[0];
-};
+} ____cacheline_aligned_in_smp;
/**
* ipc_rcu_alloc - allocate ipc and rcu space
@@ -488,12 +486,14 @@ void *ipc_rcu_alloc(int size)
if (unlikely(!out))
return NULL;
atomic_set(&out->refcount, 1);
- return out->data;
+ return out + 1;
}
int ipc_rcu_getref(void *ptr)
{
- return atomic_inc_not_zero(&container_of(ptr, struct ipc_rcu, data)->refcount);
+ struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
+
+ return atomic_inc_not_zero(&p->refcount);
}
/**
@@ -507,7 +507,7 @@ static void ipc_schedule_free(struct rcu
void ipc_rcu_putref(void *ptr)
{
- struct ipc_rcu *p = container_of(ptr, struct ipc_rcu, data);
+ struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
if (!atomic_dec_and_test(&p->refcount))
return;
Patches currently in stable-queue which might be from manfred@xxxxxxxxxxxxxxxx are
queue-3.10/ipc-sem-separate-wait-for-zero-and-alter-tasks-into-seperate-queues.patch
queue-3.10/ipc-util.c-ipc_rcu_alloc-cacheline-align-allocation.patch
queue-3.10/ipc-sem.c-cacheline-align-the-semaphore-structures.patch
queue-3.10/ipc-sem.c-always-use-only-one-queue-for-alter-operations.patch
queue-3.10/ipc-sem.c-rename-try_atomic_semop-to-perform_atomic_semop-docu-update.patch
queue-3.10/ipc-sem.c-replace-shared-sem_otime-with-per-semaphore-value.patch
--
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