Messages in this thread Patch in this message |  | | Date | Mon, 27 Oct 2014 20:54:25 +0100 | From | Oleg Nesterov <> | Subject | [PATCH 2/3] introduce probe_slab_address() |
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Extract the ifdef(CONFIG_DEBUG_PAGEALLOC) code from get_freepointer_safe() into the new generic helper, probe_slab_address(). The next patch will add another user.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- include/linux/uaccess.h | 15 +++++++++++++++ mm/slub.c | 6 +----- 2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index effb637..3367396 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -71,6 +71,21 @@ static inline unsigned long __copy_from_user_nocache(void *to, __probe_kernel_read(&(retval), (__force void *)(addr), sizeof(retval)) /* + * Same as probe_kernel_address(), but @addr must be the valid pointer + * to a slab object, potentially freed/reused/unmapped. + */ +#ifdef CONFIG_DEBUG_PAGEALLOC +#define probe_slab_address(addr, retval) \ + probe_kernel_address(addr, retval) +#else +#define probe_slab_address(addr, retval) \ + ({ \ + (retval) = *(typeof(retval) *)(addr); \ + 0; \ + }) +#endif + +/* * probe_kernel_read(): safely attempt to read from a location * @dst: pointer to the buffer that shall take the data * @src: address to read from diff --git a/mm/slub.c b/mm/slub.c index 3e8afcc..0467d22 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -265,11 +265,7 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) { void *p; -#ifdef CONFIG_DEBUG_PAGEALLOC - probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p)); -#else - p = get_freepointer(s, object); -#endif + probe_slab_address(object + s->offset, p); return p; } -- 1.5.5.1
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