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Message-ID: <CAHmME9qp5J6yhj+TYtZEhC-snqWB85gdYQ1=-eUysaYT8BkgwQ@mail.gmail.com> Date: Wed, 7 Jun 2017 20:16:05 +0200 From: "Jason A. Donenfeld" <Jason@...c4.com> To: kbuild test robot <lkp@...el.com> Cc: kbuild-all@...org, "Theodore Ts'o" <tytso@....edu>, Linux Crypto Mailing List <linux-crypto@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, kernel-hardening@...ts.openwall.com, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, David Miller <davem@...emloft.net> Subject: Re: [PATCH v3 03/13] random: invalidate batched entropy after crng init Strange, not all compilers do this warning. Fixing with: diff --git a/drivers/char/random.c b/drivers/char/random.c index 12758db..5252690 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -2061,8 +2061,8 @@ static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64); u64 get_random_u64(void) { u64 ret; - bool use_lock = crng_init < 2; - unsigned long flags; + const bool use_lock = READ_ONCE(crng_init) < 2; + unsigned long flags = 0; struct batched_entropy *batch; #if BITS_PER_LONG == 64 @@ -2099,8 +2099,8 @@ static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32); u32 get_random_u32(void) { u32 ret; - bool use_lock = crng_init < 2; - unsigned long flags; + const bool use_lock = READ_ONCE(crng_init) < 2; + unsigned long flags = 0; struct batched_entropy *batch; if (arch_get_random_int(&ret)) Const, because it's more correct. READ_ONCE to be certain that the compiler doesn't try to paste the expression into both uses. And finally flags=0 to shutup the compiler. If anybody has a better way of approaching this, feel free to chime in.
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