On Mon, Sep 14 2015 at 9:46am -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > On Sun, 13 Sep 2015, Julia Lawall wrote: > > > Remove unneeded NULL test. > > > > The semantic patch that makes this change is as follows: > > (http://coccinelle.lip6.fr/) > > > > // <smpl> > > @@ expression x; @@ > > -if (x != NULL) > > \(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x); > > // </smpl> > > > > Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxx> > > > > --- > > drivers/md/dm-bufio.c | 3 +-- > > drivers/md/dm-cache-target.c | 3 +-- > > drivers/md/dm-crypt.c | 6 ++---- > > drivers/md/dm-io.c | 3 +-- > > drivers/md/dm-log-userspace-base.c | 3 +-- > > drivers/md/dm-region-hash.c | 4 +--- > > drivers/md/dm.c | 13 ++++--------- > > 7 files changed, 11 insertions(+), 24 deletions(-) > > > > diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c > > index 83cc52e..8ad39b6 100644 > > --- a/drivers/md/dm-bufio.c > > +++ b/drivers/md/dm-bufio.c > > @@ -1864,8 +1864,7 @@ static void __exit dm_bufio_exit(void) > > for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) { > > struct kmem_cache *kc = dm_bufio_caches[i]; > > > > - if (kc) > > - kmem_cache_destroy(kc); > > + kmem_cache_destroy(kc); > > } > > The variable here can be NULL. I don't know how did you conclude that it > cannot. It seems that you didn't test the patch, if you did, you'd hit > NULL pointer dereference here. kmem_cache_destroy(), mempool_destroy(), etc all check for NULL and just return. So there is no need for the callers to check for NULL too. Mike -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
