Messages in this thread | | | Date | Fri, 21 Sep 2007 12:34:25 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 2/3] user.c: use kmem_cache_zalloc() |
| |
On Fri, 21 Sep 2007 13:39:06 +0400 Alexey Dobriyan <adobriyan@sw.ru> wrote:
> Quite a few fields are zeroed during user_struct creation, so use > kmem_cache_zalloc() -- save a few lines and #ifdef. Also will help avoid > #ifdef CONFIG_POSIX_MQUEUE in next patch. > > Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> > --- > > kernel/user.c | 13 +------------ > 1 file changed, 1 insertion(+), 12 deletions(-) > > --- a/kernel/user.c > +++ b/kernel/user.c > @@ -129,21 +129,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid) > if (!up) { > struct user_struct *new; > > - new = kmem_cache_alloc(uid_cachep, GFP_KERNEL); > + new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL); > if (!new) > return NULL; > new->uid = uid; > atomic_set(&new->__count, 1); > - atomic_set(&new->processes, 0); > - atomic_set(&new->files, 0); > - atomic_set(&new->sigpending, 0); > -#ifdef CONFIG_INOTIFY_USER > - atomic_set(&new->inotify_watches, 0); > - atomic_set(&new->inotify_devs, 0); > -#endif > - > - new->mq_bytes = 0; > - new->locked_shm = 0;
This assumes that setting an atomic_t to the all-zeroes pattern is equivalent to atomic_set(v, 0).
This happens to be true for all present architectures, afaik. But an architecture which has crappy primitives could quite legitimately implement its atomic_t as:
typedef struct { int counter; spinlock_t lock; } atomic_t;
in which case your assumption breaks.
So it's all a bit theoretical and a bit anal, and I'm sure we're making the same mistake in other places, but it's not a change I particularly like.. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |