Re: [bug report] powerpc/mm/radix: Add tlbflush routines

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

On 01/31/2018 09:31 PM, Christophe LEROY wrote:
> 
> 
> Le 31/01/2018 à 16:45, Dan Carpenter a écrit :
>> Hello Aneesh Kumar K.V,
>>
>> The patch 1a472c9dba6b: "powerpc/mm/radix: Add tlbflush routines"
>> from Apr 29, 2016, leads to the following static checker warning:
>>
>>     arch/powerpc/mm/tlb_nohash.c:218 __local_flush_tlb_page()
>>     warn: always true condition '(pid != ~0) => (0-u32max != u64max)'
>>
>> arch/powerpc/mm/tlb_nohash.c
>>     211  void __local_flush_tlb_page(struct mm_struct *mm, unsigned 
>> long vmaddr,
>>     212                              int tsize, int ind)
>>     213  {
>>     214          unsigned int pid;
>>     215
>>     216          preempt_disable();
>>     217          pid = mm ? mm->context.id : 0;
>>     218          if (pid != MMU_NO_CONTEXT)
>>                      ^^^^^^^^^^^^^^^^^^^^^
>>     219                  _tlbil_va(vmaddr, pid, tsize, ind);
>>     220          preempt_enable();
>>     221  }
>>
>> I don't know very much about PowerPC.  The static checker is guessing
>> which headers to pull in instead of relying on the build system so there
>> are a lot of false positives.  It's apparently using the
>> arch/powerpc/include/asm/book3s/64/tlbflush.h header which does:
>>
>> #define MMU_NO_CONTEXT ~0UL
>>
>> so it's UINT_MAX vs U64_MAX which is making the checker complain.
> 
> As far as I can see from arch/powerpc/include/asm/mmu-hash64.h, 
> mm->context.id is an unsigned long, so pid should also be an unsigned 
> long, not an unsigned int ?
> 
> Christophe
> 

yes.

We did similar fixup for book3s radix
in 9690c15742688e9cb5ee4aa0b08e458551ceea13 (powerpc/mm/radix: Fix 
always false comparison against MMU_NO_CONTEXT
)

-aneesh