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Date: Sat, 26 Sep 2026 13:19:27 +0100
From: Nathan Chancellor <nathan@kernel.org>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: Andy Lutomirski <luto@kernel.org>, Thomas Gleixner <tglx@kernel.org>,
	Theodore Ts'o <tytso@mit.edu>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>,
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	Madhavan Srinivasan <maddy@linux.ibm.com>,
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	Nicholas Piggin <npiggin@gmail.com>,
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Subject: Re: [PATCH v2] random: vDSO: Avoid call to memset() when zeroing
 reserved in __cvdso_getrandom_data()
Message-ID: <20260926121927.GA1486962@ax162>
References: <20260925-vdso-getrandom-avoid-memset-llvm-24-v2-1-ce640f872393@kernel.org>
 <87zex4ic68.fsf@linux-m68k.org>
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In-Reply-To: <87zex4ic68.fsf@linux-m68k.org>

On Sat, Sep 26, 2026 at 11:39:43AM +0200, Andreas Schwab wrote:
> On Sep 25 2026, Nathan Chancellor wrote:
> 
> > +#if __has_builtin(__builtin_memset_inline)
> > +#define memset_inline(dst, value, size) __builtin_memset_inline(dst, value, size)
> > +#elif IS_ENABLED(CONFIG_CC_HAS_OPT_INLINE_MEMSET)
> > +#define memset_inline(dst, value, size) __builtin_memset(dst, value, size)
> > +#else
> > +static inline void *memset_inline(void *dst, int value, size_t size)
> > +{
> > +	char *d = dst;
> > +
> > +	while (size--)
> > +		*d++ = value;
> > +
> > +	return d;
> > +}
> > +#endif
> > +
> 
> memset actually returns the original pointer, not the incremented one.
> Nothing uses the return value of memset_inline here, but it is
> confusing.

Whoops, good catch, I guess my fingers gave up on those last two
characters :) I will fix this for v3 once there has been some time for
further review.

-- 
Cheers,
Nathan