Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752151AbaAXDKa (ORCPT ); Thu, 23 Jan 2014 22:10:30 -0500 Received: from mail-oa0-f53.google.com ([209.85.219.53]:62035 "EHLO mail-oa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750969AbaAXDK2 (ORCPT ); Thu, 23 Jan 2014 22:10:28 -0500 MIME-Version: 1.0 In-Reply-To: <20140123132325.cada6dca726c2cdd1173ad91@linux-foundation.org> References: <1390470990-16065-1-git-send-email-prabhakar.csengg@gmail.com> <20140123132325.cada6dca726c2cdd1173ad91@linux-foundation.org> Date: Fri, 24 Jan 2014 08:40:28 +0530 Message-ID: Subject: Re: [PATCH] lib/genalloc.c: add check gen_pool_dma_alloc() if dma pointer is not NULL From: Sachin Kamat To: Andrew Morton Cc: Prabhakar Lad , Philipp Zabel , Nicolin Chen , Joe Perches , LKML , DLOS Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24 January 2014 02:53, Andrew Morton wrote: > On Thu, 23 Jan 2014 15:51:31 +0530 Prabhakar Lad wrote: > >> Hi Sachin, >> >> On Thu, Jan 23, 2014 at 3:38 PM, Sachin Kamat wrote: >> > Hi Prabhakar, >> > >> > On 23 January 2014 15:26, Prabhakar Lad wrote: >> >> From: "Lad, Prabhakar" >> >> >> >> In the gen_pool_dma_alloc() the dma pointer can be NULL >> >> and while assigning gen_pool_virt_to_phys(pool, vaddr) to >> >> dma caused the following crash on da850 evm, >> >> >> > [snip] >> >> >> >> Signed-off-by: Lad, Prabhakar >> >> --- >> >> lib/genalloc.c | 3 ++- >> >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> >> >> diff --git a/lib/genalloc.c b/lib/genalloc.c >> >> index dda3116..f48163f 100644 >> >> --- a/lib/genalloc.c >> >> +++ b/lib/genalloc.c >> >> @@ -334,7 +334,8 @@ void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma) >> >> if (!vaddr) >> >> return NULL; >> >> >> >> - *dma = gen_pool_virt_to_phys(pool, vaddr); >> >> + if (dma) >> >> + *dma = gen_pool_virt_to_phys(pool, vaddr); >> > >> > Wouldn't it be better to return (with error/message) if dma is NULL >> > rather than silently ignore it? >> > >> I am not sure if returning here with error is OK, >> may be just adding a warning message could be OK ? > > The patch look OK as-is to me. `dma' is a second return value from > gen_pool_dma_alloc() and this patch extends the gen_pool_dma_alloc() > interface by making that return value optional. That's good for > callers who don't want the physical address, and they can call > gen_pool_virt_to_phys() at a later time to get the physical address > anyway. > > From my reading, 3.13.x kernels will need this patch. > > I suppose we should document the API change: > > --- a/lib/genalloc.c~lib-genallocc-add-check-gen_pool_dma_alloc-if-dma-pointer-is-not-null-fix > +++ a/lib/genalloc.c > @@ -316,7 +316,7 @@ EXPORT_SYMBOL(gen_pool_alloc); > * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage > * @pool: pool to allocate from > * @size: number of bytes to allocate from the pool > - * @dma: dma-view physical address > + * @dma: dma-view physical address return value. Use NULL if unneeded. Makes sense. Thanks Andrew. -- With warm regards, Sachin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/