From: Manfred Spraul Date: Sat, 3 Sep 2005 22:55:07 +0000 (-0700) Subject: [PATCH] slab: removes local_irq_save()/local_irq_restore() pair X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=00e145b6d59a16dd7740197a18f7abdb3af004a9;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git [PATCH] slab: removes local_irq_save()/local_irq_restore() pair Proposed by and based on a patch from Eric Dumazet : 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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))); }