| Message ID | 20190715031851.6890-1-huangfq.daxian@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | None | expand |
On 7/15/19 05:18, Fuqian Huang wrote: > In commit 518a2f1925c3 > ("dma-mapping: zero memory returned from dma_alloc_*"), > dma_alloc_coherent has already zeroed the memory. > So memset is not needed I can't see any changes in the above mentioned commit that would make dma_alloc_coherent() (arm_coherent_dma_alloc()) zeroing its returned memory. Maybe you need to add a reference to some other instead? > Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com> > drivers/media/platform/exynos4-is/fimc-is.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/media/platform/exynos4-is/fimc-is.c b/drivers/media/platform/exynos4-is/fimc-is.c > index e043d55133a3..77633e356305 100644 > --- a/drivers/media/platform/exynos4-is/fimc-is.c > +++ b/drivers/media/platform/exynos4-is/fimc-is.c > @@ -341,7 +341,6 @@ static int fimc_is_alloc_cpu_memory(struct fimc_is *is) > return -ENOMEM; > > is->memory.size = FIMC_IS_CPU_MEM_SIZE; > - memset(is->memory.vaddr, 0, is->memory.size); -- Thanks, Sylwester
Sylwester Nawrocki <s.nawrocki@samsung.com> 於 2019年7月15日週一 下午5:00寫道： > > On 7/15/19 05:18, Fuqian Huang wrote: > > In commit 518a2f1925c3 > > ("dma-mapping: zero memory returned from dma_alloc_*"), > > dma_alloc_coherent has already zeroed the memory. > > So memset is not needed > > I can't see any changes in the above mentioned commit that would > make dma_alloc_coherent() (arm_coherent_dma_alloc()) zeroing its > returned memory. Maybe you need to add a reference to some other > instead? > In the last version patch set, I referenced the commit af7ddd8a627c ("Merge tag 'dma-mapping-4.21' of git://git.infradead.org/users/hch/dma-mapping") in the commit log. The merged commit mentions that "ensure dma_alloc_coherent returns zeroed memory to avoid kernel data leaks through userspace. We already did this for most common architectures, but this ensures we do it everywhere." dma_alloc_coherent has already zeroed the memory during allocation and the commit also deprecates dma_zalloc_coherent. Greg and other maintainer told me to use the actual commit rather than the merged commit. So I reference the commit that ensures the dma_alloc_coherent to returns zeroed memory every where. Maybe this belongs to the `most common achitectures` and is not impacted by the mentioned change. Should I rewrite the commit log? Just mention that dma_alloc_coherent has already zeroed the memory and not to reference the commit?
On 7/15/19 11:43, Fuqian Huang wrote: > Should I rewrite the commit log? Just mention that dma_alloc_coherent > has already zeroed the memory and not to reference the commit? I don't think it is really needed, since at hash 518a2f1925c3 dma_alloc_coherent() already zeroes the memory, so in fact all statements in your current commit message are true.
On 7/15/19 05:18, Fuqian Huang wrote: > In commit 518a2f1925c3 > ("dma-mapping: zero memory returned from dma_alloc_*"), > dma_alloc_coherent has already zeroed the memory. > So memset is not needed > > Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com> Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
diff --git a/drivers/media/platform/exynos4-is/fimc-is.c b/drivers/media/platform/exynos4-is/fimc-is.c index e043d55133a3..77633e356305 100644 --- a/drivers/media/platform/exynos4-is/fimc-is.c +++ b/drivers/media/platform/exynos4-is/fimc-is.c @@ -341,7 +341,6 @@ static int fimc_is_alloc_cpu_memory(struct fimc_is *is) return -ENOMEM; is->memory.size = FIMC_IS_CPU_MEM_SIZE; - memset(is->memory.vaddr, 0, is->memory.size); dev_info(dev, "FIMC-IS CPU memory base: %#x\n", (u32)is->memory.paddr);
In commit 518a2f1925c3 ("dma-mapping: zero memory returned from dma_alloc_*"), dma_alloc_coherent has already zeroed the memory. So memset is not needed Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com> --- Changes in v3: - Use actual commit rather than the merge commit in the commit message drivers/media/platform/exynos4-is/fimc-is.c | 1 - 1 file changed, 1 deletion(-)