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authorManfred Spraul <manfred@colorfullife.com>2005-09-03 15:55:07 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:05:49 -0700
commit00e145b6d59a16dd7740197a18f7abdb3af004a9 (patch)
tree7b081ccfa6a34e5a17f4f1d6925d4945df2a97c1 /mm
parent34342e863c3143640c031760140d640a06c6a5f8 (diff)
downloadlinux-sh-00e145b6d59a16dd7740197a18f7abdb3af004a9.tar.gz
[PATCH] slab: removes local_irq_save()/local_irq_restore() pair
Proposed by and based on a patch from Eric Dumazet <dada1@cosmosbay.com>: This patch removes unnecessary critical section in ksize() function, as cli/sti are rather expensive on modern CPUS. It additionally adds a docbook entry for ksize() and further simplifies the code. Signed-Off-By: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/slab.c26
1 files changed, 15 insertions, 11 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 75127a6f1fd9..a9ff4f7f9860 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3076,20 +3076,24 @@ ssize_t slabinfo_write(struct file *file, const char __user *buffer,
}
#endif
+/**
+ * ksize - get the actual amount of memory allocated for a given object
+ * @objp: Pointer to the object
+ *
+ * kmalloc may internally round up allocations and return more memory
+ * than requested. ksize() can be used to determine the actual amount of
+ * memory allocated. The caller may use this additional memory, even though
+ * a smaller amount of memory was initially specified with the kmalloc call.
+ * The caller must guarantee that objp points to a valid object previously
+ * allocated with either kmalloc() or kmem_cache_alloc(). The object
+ * must not be freed during the duration of the call.
+ */
unsigned int ksize(const void *objp)
{
- kmem_cache_t *c;
- unsigned long flags;
- unsigned int size = 0;
-
- if (likely(objp != NULL)) {
- local_irq_save(flags);
- c = GET_PAGE_CACHE(virt_to_page(objp));
- size = kmem_cache_size(c);
- local_irq_restore(flags);
- }
+ if (unlikely(objp == NULL))
+ return 0;
- return size;
+ return obj_reallen(GET_PAGE_CACHE(virt_to_page(objp)));
}