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x86/boot: Standardize strcmp()

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strcmp() is always expected to return 0 when arguments are equal,
negative when its first argument @str1 is less than its second argument
@str2 and a positive value otherwise. Previously strcmp("a", "b")
returned 1. Now it gives -1, as it is supposed to.

Until now this bug never triggered, because all uses for strcmp() in the
boot code tested for nonzero:

  triton:~/tip> git grep strcmp arch/x86/boot/
  arch/x86/boot/boot.h:int strcmp(const char *str1, const char *str2);
  arch/x86/boot/edd.c:            if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) {
  arch/x86/boot/edd.c:            else if (!strcmp(eddarg, "off"))
  arch/x86/boot/edd.c:            else if (!strcmp(eddarg, "on"))

should in the future strcmp() be used in a comparative way in the boot
code, it might have led to (not so subtle) bugs.

Signed-off-by: Arjun Sreedharan <arjun024@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426520267-1803-1-git-send-email-arjun024@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Arjun Sreedharan 2015-03-16 21:07:47 +05:30 committed by Ingo Molnar
parent 91d8f0416f
commit 1c1d046be6
1 changed files with 1 additions and 1 deletions
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2
arch/x86/boot/string.c
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@ -30,7 +30,7 @@ int strcmp(const char *str1, const char *str2)
int delta = 0;
while (*s1 || *s2) {
delta = *s2 - *s1;
delta = *s1 - *s2;
if (delta)
return delta;
s1++;