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authorManfred Spraul <manfred@colorfullife.com>2013-07-08 16:01:20 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-10-18 07:45:46 -0700
commit49f7f31ab27de9bcaf2d12e1d0196400dadf6add (patch)
treeb95d01d51e49db3e79e8d49c8b856b54938612eb /ipc
parent5cd37e921753eeff777a522aa78b0cc5a6ff7596 (diff)
downloadlinaro-lsk-49f7f31ab27de9bcaf2d12e1d0196400dadf6add.tar.gz
ipc/util.c, ipc_rcu_alloc: cacheline align allocation
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@linux-foundation.org: coding-style fixes] Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Rik van Riel <riel@redhat.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/util.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/ipc/util.c b/ipc/util.c
index a0c139f3d1f..4704223bfad 100644
--- 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_head *head)
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;