On Mon, May 10, 2021 at 3:08 PM kernel test robot <lkp@xxxxxxxxx> wrote:
>
> In file included from include/linux/kernel.h:10,
> from drivers/media/rc/nuvoton-cir.c:25:
> include/linux/scatterlist.h: In function 'sg_set_buf':
> include/asm-generic/page.h:89:50: warning: ordered comparison of pointer with null pointer [-Wextra]
> 89 | #define virt_addr_valid(kaddr) (((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
> | ^~
> include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
> 78 | # define unlikely(x) __builtin_expect(!!(x), 0)
> | ^
> include/linux/scatterlist.h:137:2: note: in expansion of macro 'BUG_ON'
> 137 | BUG_ON(!virt_addr_valid(buf));
> | ^~~~~~
> include/linux/scatterlist.h:137:10: note: in expansion of macro 'virt_addr_valid'
> 137 | BUG_ON(!virt_addr_valid(buf));
> | ^~~~~~~~~~~~~~~
> drivers/media/rc/nuvoton-cir.c: In function 'nvt_get_rx_ir_data':
> >> drivers/media/rc/nuvoton-cir.c:761:15: warning: iteration 32 invokes undefined behavior [-Waggressive-loop-optimizations]
> 761 | nvt->buf[i] = nvt_cir_reg_read(nvt, CIR_SRXFIFO);
I think you can ignore this one, it's a preexisting issue with this
driver that gets uncovered by your patch: if "fifocount" is read from
a broken device as 0xff, the loop causes a buffer overflow.
The code is already unreachable because the interrupt handler
will have aborted already, so the compiler's dead code elimination
should have shut up that warning, but adding a range check
before the loop would address this as well.
As far as I can tell, this warning only shows up when building with
"make W=1".
Arnd
