diff options
| author | Manfred Spraul <manfred@colorfullife.com> | 2013-07-08 16:01:20 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-18 07:45:46 -0700 |
| commit | 49f7f31ab27de9bcaf2d12e1d0196400dadf6add (patch) | |
| tree | b95d01d51e49db3e79e8d49c8b856b54938612eb /ipc | |
| parent | 5cd37e921753eeff777a522aa78b0cc5a6ff7596 (diff) | |
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.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/ipc/util.c b/ipc/util.c index a0c139f3d1f3..4704223bfad4 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; |