From: Daniel Borkmann Subject: [PATCH] lib: memzero_explicit: add comment for its usage Date: Tue, 6 Jan 2015 00:27:45 +0100 Message-ID: <1420500465-6522-1-git-send-email-dborkman@redhat.com> Cc: linux-crypto@vger.kernel.org To: herbert@gondor.apana.org.au Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41475 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753031AbbAEX1v (ORCPT ); Mon, 5 Jan 2015 18:27:51 -0500 Sender: linux-crypto-owner@vger.kernel.org List-ID: Lets improve the comment to add a note on when to use memzero_explicit() for those not digging through the git logs. We don't want people to pollute places with memzero_explicit() where it's not really necessary. Reference: https://lkml.org/lkml/2015/1/4/190 Suggested-by: Herbert Xu Signed-off-by: Daniel Borkmann --- [ Sending to -crypto as it's most relevant here and suggested by Herbert anyway. ] lib/string.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/lib/string.c b/lib/string.c index 1006330..d984ec4 100644 --- a/lib/string.c +++ b/lib/string.c @@ -604,6 +604,11 @@ EXPORT_SYMBOL(memset); * @s: Pointer to the start of the area. * @count: The size of the area. * + * Note: usually using memset() is just fine (!), but in cases + * where clearing out _local_ data at the end of a scope is + * necessary, memzero_explicit() should be used instead in + * order to prevent the compiler from optimising away zeroing. + * * memzero_explicit() doesn't need an arch-specific version as * it just invokes the one of memset() implicitly. */ -- 1.7.11.7