RE: [PATCH] hexagon: fix using plain integer as NULL pointer warning in cmpxchg

[Brian Cain]

> -----Original Message-----
> From: Maíra Canal <mcanal@xxxxxxxxxx>
> Sent: Sunday, January 26, 2025 4:59 PM
> To: Christian Gmeiner <christian.gmeiner@xxxxxxxxx>; Willem de Bruijn
> <willemdebruijn.kernel@xxxxxxxxx>
> Cc: linux-hexagon@xxxxxxxxxxxxxxx; Brian Cain <bcain@xxxxxxxxxxx>; linux-
> kernel@xxxxxxxxxxxxxxx; dhowells@xxxxxxxxxx; edumazet@xxxxxxxxxx;
> Willem de Bruijn <willemb@xxxxxxxxxx>; kernel test robot <lkp@xxxxxxxxx>;
> mcanal@xxxxxxxxxx
> Subject: Re: [PATCH] hexagon: fix using plain integer as NULL pointer warning
> in cmpxchg
> 
> WARNING: This email originated from outside of Qualcomm. Please be wary of
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> 
> Hi Brian,
> 
> Do you have an estimate for when this patch will be picked? We are
> getting build reports from Hexagon in the V3D GPU driver [1].

Sorry for the delay.  I will work on it this week, Maíra.

> [1]
> https://lore.kernel.org/oe-kbuild-all/202501031246.AD8Jjze0-lkp@xxxxxxxxx/
> 
> Best Regards,
> - Maíra
> 
> On 07/01/25 07:17, Christian Gmeiner wrote:
> > Hi Willem,
> >
> >>
> >> From: Willem de Bruijn <willemb@xxxxxxxxxx>
> >>
> >> Sparse reports
> >>
> >>      net/ipv4/inet_diag.c:1511:17: sparse: sparse: Using plain integer as NULL
> pointer
> >>
> >> Due to this code calling cmpxchg on a non-integer type
> >> struct inet_diag_handler *
> >>
> >>      return !cmpxchg((const struct
> inet_diag_handler**)&inet_diag_table[type],
> >>                      NULL, h) ? 0 : -EEXIST;
> >>
> >> While hexagon's cmpxchg assigns an integer value to a variable of this
> >> type.
> >>
> >>      __typeof__(*(ptr)) __oldval = 0;
> >>
> >> Update this assignment to cast 0 to the correct type.
> >>
> >> The original issue is easily reproduced at head with the below block,
> >> and is absent after this change.
> >>
> >>      make LLVM=1 ARCH=hexagon defconfig
> >>      make C=1 LLVM=1 ARCH=hexagon net/ipv4/inet_diag.o
> >>
> >> Fixes: 99a70aa051d2 ("Hexagon: Add processor and system headers")
> >> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >> Closes: https://lore.kernel.org/oe-kbuild-all/202411091538.PGSTqUBi-
> lkp@xxxxxxxxx/
> >> Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx>
> >
> > Closes: https://lore.kernel.org/oe-kbuild-all/202501031246.AD8Jjze0-
> lkp@xxxxxxxxx/
> > Tested-by: Christian Gmeiner <cgmeiner@xxxxxxxxxx>
> >
> >> ---
> >>   arch/hexagon/include/asm/cmpxchg.h | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/arch/hexagon/include/asm/cmpxchg.h
> b/arch/hexagon/include/asm/cmpxchg.h
> >> index bf6cf5579cf4..9c58fb81f7fd 100644
> >> --- a/arch/hexagon/include/asm/cmpxchg.h
> >> +++ b/arch/hexagon/include/asm/cmpxchg.h
> >> @@ -56,7 +56,7 @@ __arch_xchg(unsigned long x, volatile void *ptr, int
> size)
> >>          __typeof__(ptr) __ptr = (ptr);                          \
> >>          __typeof__(*(ptr)) __old = (old);                       \
> >>          __typeof__(*(ptr)) __new = (new);                       \
> >> -       __typeof__(*(ptr)) __oldval = 0;                        \
> >> +       __typeof__(*(ptr)) __oldval = (__typeof__(*(ptr))) 0;   \
> >>                                                                  \
> >>          asm volatile(                                           \
> >>                  "1:     %0 = memw_locked(%1);\n"                \
> >> --
> >> 2.47.0.338.g60cca15819-goog
> >>
> >>
> >
> >