Re: [PATCH] i2c: mediatek: modify threshold passed to i2c_get_dma_safe_msg_buf()

From: Hsin-Yi Wang
Date: Fri Feb 15 2019 - 04:17:42 EST

Ok, I can add a check in another patch. Should we return NULL pointer
if msg->len is 0 or print out some warnings? Thanks.

On Fri, Feb 15, 2019 at 5:10 PM Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote:
> On Fri, Feb 15, 2019 at 05:02:02PM +0800, Hsin-Yi Wang wrote:
> > i2c_get_dma_safe_msg_buf() allocates space based on msg->len. If threshold is
> > 0 and msg->len is also 0, function makes zero-length allocation, which returns
> > a special ZERO_SIZE_PTR instead of a NULL pointer, and this will cause later
> > code to fail. Modify the threshold to > 0 so the function returns NULL pointer.
> >
> > Fixes: fc66b39fe36a ("i2c: mediatek: Use DMA safe buffers for i2c transactions")
> > Signed-off-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
> Right. But we need to fix i2c_get_dma_safe_msg_buf(), so it will be
> handled for all callers. Do you want to add a check if msg->len is 0 or
> shall I? Both fine for me.