Messages in this thread | | | From | Yury Norov <> | Date | Mon, 28 Dec 2020 12:10:46 -0800 | Subject | Re: [PATCH] drm/komeda: use bitmap API to convert U32 to bitmap |
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On Mon, Dec 28, 2020 at 11:49 AM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > On Mon, Dec 28, 2020 at 11:43:43AM -0800, Yury Norov wrote: > > The commit be3e477effba636ad25 ("drm/komeda: Fix bit > > check to import to value of proper type") fixes possible > > out-of-bound issue related to find_first_bit() usage, but > > does not address the endianness problem. > > Hmm... Can you elaborate? > > ... > > > u32 comp_mask) > > > - unsigned long comp_mask_local = (unsigned long)comp_mask; > > Here we convert u32 to unsigned long (LSB is kept LSB since it happens in > native endianess). > > > - id = find_first_bit(&comp_mask_local, 32); > > Here it takes an address to unsigned long and tries only lower 32 bits. > > Are you telling that find_first_bit() has an issue?
It seems you're right, there's no issue with endianness in existing code. In fact, the line
> > - unsigned long comp_mask_local = (unsigned long)comp_mask;
is an opencoded version of bitmap_from_arr32(dst, src, 32).
Maybe it would be better to use the bitmap API here, but existing code is correct. Sorry for the noise.
Yury
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