From: Ingo Molnar <mingo@elte.hu>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
systemtap <systemtap@sources.redhat.com>,
DLE <dle-develop@lists.sourceforge.net>
Subject: Re: [PATCH -tip 1/2] x86/alternatives: Fix build warning
Date: Fri, 05 Feb 2010 07:13:00 -0000 [thread overview]
Message-ID: <20100205071249.GB9320@elte.hu> (raw)
In-Reply-To: <20100205062427.3745.85746.stgit@dhcp-100-2-132.bos.redhat.com>
* Masami Hiramatsu <mhiramat@redhat.com> wrote:
> Fixes below warnings.
>
> ====
> FYI, there's this new build warning on x86 defconfig:
>
> arch/x86/kernel/alternative.c: In function 'alternatives_text_reserved':
> arch/x86/kernel/alternative.c:402: warning: comparison of distinct pointer types lacks a cast
> arch/x86/kernel/alternative.c:402: warning: comparison of distinct pointer types lacks a cast
> arch/x86/kernel/alternative.c:405: warning: comparison of distinct pointer types lacks a cast
> arch/x86/kernel/alternative.c:405: warning: comparison of distinct pointer types lacks a cast
>
> Caused by:
>
> 2cfa197: ftrace/alternatives: Introducing *_text_reserved functions
> ====
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Reported-by: Ingo Molnar <mingo@elte.hu>
> ---
>
> arch/x86/kernel/alternative.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
> index 3832fdc..99d9920 100644
> --- a/arch/x86/kernel/alternative.c
> +++ b/arch/x86/kernel/alternative.c
> @@ -399,10 +399,10 @@ int alternatives_text_reserved(void *start, void *end)
> u8 **ptr;
>
> list_for_each_entry(mod, &smp_alt_modules, next) {
> - if (mod->text > end || mod->text_end < start)
> + if (mod->text > (u8 *)end || mod->text_end < (u8 *)start)
> continue;
> for (ptr = mod->locks; ptr < mod->locks_end; ptr++)
> - if (start <= *ptr && end >= *ptr)
> + if ((u8 *)start <= *ptr && (u8 *)end >= *ptr)
> return 1;
> }
Such casts are a bit ugly and in general type casts are somewhat dangerous.
One possible solution would be to add intermediary local variables
(text_start/text_end) with u8 * type and assign start/end to them - which can
be done without a cast.
Thanks,
Ingo
next prev parent reply other threads:[~2010-02-05 7:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-05 6:16 Masami Hiramatsu
2010-02-05 6:16 ` [PATCH -tip 2/2] kprobes: Add mcount in kprobes blacklist Masami Hiramatsu
2010-02-05 7:51 ` [tip:perf/core] kprobes: Add mcount to the " tip-bot for Masami Hiramatsu
2010-02-15 5:23 ` [tip:tracing/urgent] " tip-bot for Masami Hiramatsu
2010-02-05 7:13 ` Ingo Molnar [this message]
2010-02-05 16:52 ` [PATCH -tip 1/2] x86/alternatives: Fix build warning Masami Hiramatsu
2010-02-05 17:09 ` [PATCH -tip v2] " Masami Hiramatsu
2010-02-07 19:44 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
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