On Sun, Jun 05, 2022 at 06:07:38PM +0200, Luc Van Oostenryck wrote:
> On IA64, new sparse's warnings where issued after fixing
> some __rcu annotations in kernel/bpf/.
>
> These new warnings are false positives and appear on IA64 because
> on this architecture, the macros for cmpxchg() and xchg() make
> casts that ignore sparse annotations.
>
> This patch contains the minimal patch to fix this issue:
> adding a missing cast and some missing '__force'.
>
> Link: https://lore.kernel.org/r/20220601120013.bq5a3ynbkc3hngm5@mail
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Cc: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
Looks good to me!
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> ---
>
> Note: This patch is only compile tested on defconfig. The corresponding
> binary is unchanged (except some .rodata with the kernel version)
> as it should be.
>
> arch/ia64/include/uapi/asm/cmpxchg.h | 28 ++++++++++++++--------------
> 1 file changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/arch/ia64/include/uapi/asm/cmpxchg.h b/arch/ia64/include/uapi/asm/cmpxchg.h
> index 2c2f3cfeaa77..ca2e02685343 100644
> --- a/arch/ia64/include/uapi/asm/cmpxchg.h
> +++ b/arch/ia64/include/uapi/asm/cmpxchg.h
> @@ -33,24 +33,24 @@ extern void ia64_xchg_called_with_bad_pointer(void);
> \
> switch (size) { \
> case 1: \
> - __xchg_result = ia64_xchg1((__u8 *)ptr, x); \
> + __xchg_result = ia64_xchg1((__u8 __force *)ptr, x); \
> break; \
> \
> case 2: \
> - __xchg_result = ia64_xchg2((__u16 *)ptr, x); \
> + __xchg_result = ia64_xchg2((__u16 __force *)ptr, x); \
> break; \
> \
> case 4: \
> - __xchg_result = ia64_xchg4((__u32 *)ptr, x); \
> + __xchg_result = ia64_xchg4((__u32 __force *)ptr, x); \
> break; \
> \
> case 8: \
> - __xchg_result = ia64_xchg8((__u64 *)ptr, x); \
> + __xchg_result = ia64_xchg8((__u64 __force *)ptr, x); \
> break; \
> default: \
> ia64_xchg_called_with_bad_pointer(); \
> } \
> - __xchg_result; \
> + (__typeof__ (*(ptr)) __force) __xchg_result; \
> })
>
> #ifndef __KERNEL__
> @@ -76,42 +76,42 @@ extern long ia64_cmpxchg_called_with_bad_pointer(void);
> \
> switch (size) { \
> case 1: \
> - _o_ = (__u8) (long) (old); \
> + _o_ = (__u8) (long __force) (old); \
> break; \
> case 2: \
> - _o_ = (__u16) (long) (old); \
> + _o_ = (__u16) (long __force) (old); \
> break; \
> case 4: \
> - _o_ = (__u32) (long) (old); \
> + _o_ = (__u32) (long __force) (old); \
> break; \
> case 8: \
> - _o_ = (__u64) (long) (old); \
> + _o_ = (__u64) (long __force) (old); \
> break; \
> default: \
> break; \
> } \
> switch (size) { \
> case 1: \
> - _r_ = ia64_cmpxchg1_##sem((__u8 *) ptr, new, _o_); \
> + _r_ = ia64_cmpxchg1_##sem((__u8 __force *) ptr, new, _o_); \
> break; \
> \
> case 2: \
> - _r_ = ia64_cmpxchg2_##sem((__u16 *) ptr, new, _o_); \
> + _r_ = ia64_cmpxchg2_##sem((__u16 __force *) ptr, new, _o_); \
> break; \
> \
> case 4: \
> - _r_ = ia64_cmpxchg4_##sem((__u32 *) ptr, new, _o_); \
> + _r_ = ia64_cmpxchg4_##sem((__u32 __force *) ptr, new, _o_); \
> break; \
> \
> case 8: \
> - _r_ = ia64_cmpxchg8_##sem((__u64 *) ptr, new, _o_); \
> + _r_ = ia64_cmpxchg8_##sem((__u64 __force *) ptr, new, _o_); \
> break; \
> \
> default: \
> _r_ = ia64_cmpxchg_called_with_bad_pointer(); \
> break; \
> } \
> - (__typeof__(old)) _r_; \
> + (__typeof__(old) __force) _r_; \
> })
>
> #define cmpxchg_acq(ptr, o, n) \
> --
> 2.36.1
>
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