| Message ID | 20140123132325.cada6dca726c2cdd1173ad91@linux-foundation.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 24 January 2014 02:53, Andrew Morton <akpm@linux-foundation.org> wrote: > On Thu, 23 Jan 2014 15:51:31 +0530 Prabhakar Lad <prabhakar.csengg@gmail.com> wrote: > >> Hi Sachin, >> >> On Thu, Jan 23, 2014 at 3:38 PM, Sachin Kamat <sachin.kamat@linaro.org> wrote: >> > Hi Prabhakar, >> > >> > On 23 January 2014 15:26, Prabhakar Lad <prabhakar.csengg@gmail.com> wrote: >> >> From: "Lad, Prabhakar" <prabhakar.csengg@gmail.com> >> >> >> >> 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 <prabhakar.csengg@gmail.com> >> >> --- >> >> 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.
--- 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. * * Allocate the requested number of bytes from the specified pool. * Uses the pool allocation function (with first-fit algorithm by default).