linux-kernel - mm/slub.c: inconsequent NULL checking

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Message-ID: <20080219224922.GO31955@cs181133002.pp.htv.fi>
Date:	Wed, 20 Feb 2008 00:49:22 +0200
From:	Adrian Bunk <bunk@...nel.org>
To:	Christoph Lameter <clameter@....com>, penberg@...helsinki.fi,
	mpm@...enic.com
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: mm/slub.c: inconsequent NULL checking

The Coverity checker spotted the following inconsequent NULL checking 
introduced by commit 8ff12cfc009a2a38d87fa7058226fe197bb2696f:

<--  snip  -->

...
static inline int is_end(void *addr)
{
        return (unsigned long)addr & PAGE_MAPPING_ANON;
}
...
static void deactivate_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
...
        if (c->freelist)    <----------------------------------------
                stat(c, DEACTIVATE_REMOTE_FREES);
        /*
         * Merge cpu freelist into freelist. Typically we get here
         * because both freelists are empty. So this is unlikely
         * to occur.
         *
         * We need to use _is_end here because deactivate slab may
         * be called for a debug slab. Then c->freelist may contain
         * a dummy pointer.
         */
        while (unlikely(!is_end(c->freelist))) {
                void **object;

                tail = 0;       /* Hot objects. Put the slab first */

                /* Retrieve object from cpu_freelist */
                object = c->freelist;
                c->freelist = c->freelist[c->offset];
...                           ^^^^^^^^^^^^^^^^^^^^^^

<--  snip  -->

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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