Messages in this thread | | | Date | Wed, 6 Nov 2019 09:59:59 +0100 | From | Petr Mladek <> | Subject | Re: [PATCH] rss_stat: Add support to detect RSS updates of external mm |
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On Tue 2019-11-05 21:44:51, Joel Fernandes (Google) wrote: > Also vsprintf.c is refactored a bit to allow reuse of hashing code.
I agree with Sergey that it would make sense to move this outside vsprintf.c.
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index dee8fc467fcf..401baaac1813 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -761,11 +761,34 @@ static int __init initialize_ptr_random(void) > early_initcall(initialize_ptr_random); > > /* Maps a pointer to a 32 bit unique identifier. */ > +int ptr_to_hashval(const void *ptr, unsigned long *hashval_out) > +{ > + const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
str is unused.
> + unsigned long hashval;
IMHO, this local variable unnecessarily complicates the code. I would use the pointer directly and let compiler to optimize.
> + if (static_branch_unlikely(¬_filled_random_ptr_key)) > + return -EAGAIN; > + > +#ifdef CONFIG_64BIT > + hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key); > + /* > + * Mask off the first 32 bits, this makes explicit that we have > + * modified the address (and 32 bits is plenty for a unique ID). > + */ > + hashval = hashval & 0xffffffff; > +#else > + hashval = (unsigned long)siphash_1u32((u32)ptr, &ptr_key); > +#endif > + *hashval_out = hashval; > + return 0; > +}
Best Regards, Petr
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