From: Andi Kleen <andi@firstfloor•org>
To: Andrew Morton <akpm@linux-foundation•org>
Cc: randy.dunlap@oracle•com, lenb@kernel•org,
linux-acpi@vger•kernel.org, linux-next@vger•kernel.org
Subject: Re: [PATCH -next] acpi utmisc: use WARN_ON() instead of warn_on_slowpath()
Date: Wed, 02 Jul 2008 22:51:52 +0200 [thread overview]
Message-ID: <486BEA68.7000801@firstfloor.org> (raw)
In-Reply-To: <20080702133540.20d578cd.akpm@linux-foundation.org>
Andrew Morton wrote:
> On Wed, 02 Jul 2008 22:11:06 +0200
> Andi Kleen <andi@firstfloor•org> wrote:
>
>> Here's a patch. Can you use that one instead of Randy's please?
>>
>
> No.
>
>> [bug-fallback text/plain (593B)]
>> Supply warn_on_slow_path() even for the !CONFIG_BUG case
>>
>> Fix build problem with ACPI for !CONFIG_BUG. Noted by Randy Dunlap.
>>
>> Signed-off-by: Andi Kleen <ak@linux•intel.com>
>>
>> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
>> index 2632328..d0d83b7 100644
>> --- a/include/asm-generic/bug.h
>> +++ b/include/asm-generic/bug.h
>> @@ -63,6 +63,9 @@ extern void warn_on_slowpath(const char *file, const int line);
>> unlikely(__ret_warn_on); \
>> })
>> #endif
>> +
>> +static inline void warn_on_slowpath(const char *file, const int line) {}
>> +
>> #endif
>
> There's no reason why asm/bug.h has to even include asm-generic/bug.h.
I checked them all and they all do.
Besides for the ACPI case we only have to care about x86 and ia64.
But all do it anyways.
> And there's no reason why an architecture which defined __WARN needs to
> define warn_on_slowpath() even if it _does_ include asm-generic/bug.h.
> And I didn't even begin to look at what might disable
> WANT_WARN_ON_SLOWPATH.
I think warn_on_slow_path() should be a general interface.
Perhaps with a better name though.
>
> This is all poking deep into the private internals of one particular
> implementation of this interface.
But it's in kernel/panic.c. I don't think anyone can compile
without that. So it should be always there (unless you undefine CONFIG_BUG)
> Furthermore even if it _does_ happen to work, you've gone and coupled
> the availability of this acpi debbugging feature to CONFIG_BUG, which
> seems arbitrary.
Well not defining CONFIG_BUG means "I don't care about debugging" doesn't it?
Not having (or having only crippled) ACPI debugging in that case seems reasonable
Doesn't seem that arbitrary to me.
>
> If you really want to do it this way (and it sounds reasonable) then
> can we please do it in a less-than-totally-hacky-and-broken way?
>
>
>
> For example, define a new, always-available helper function in (say)
> kernel/panic.c along the lines of
>
> void emit_warning_message(?)(const char *msg, int line)
Ok we can just rename warn_on_slow_path() which is already there to that new name.
Would that satisfy you?
>
> and then call that from warn_on_slowpath(). Will require that
> warn_on_slowpath become inlined so we don't get a useless extra entry
> in the backtraces all the time.
>
> Or just use printk and dump_stack.
I think the reason for the warn_on_slowpath() is that it produces
patterns that can be detected by Arjan's kerneloops scripts.
I'm not sure manual printk/dump_stack would have the same effect.
-Andi
next prev parent reply other threads:[~2008-07-02 20:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080701103339.b5acc1f3.randy.dunlap@oracle.com>
[not found] ` <20080701131714.5093fa49.akpm@linux-foundation.org>
[not found] ` <23433248.1214943818230.JavaMail.oracle@acsmt302.oracle.com>
[not found] ` <20080701133535.f92a673c.akpm@linux-foundation.org>
2008-07-02 18:28 ` [PATCH -next] acpi utmisc: use WARN_ON() instead of warn_on_slowpath() Randy Dunlap
2008-07-02 18:50 ` Andi Kleen
2008-07-02 19:14 ` Andrew Morton
2008-07-02 19:31 ` Andi Kleen
2008-07-02 19:43 ` Andrew Morton
2008-07-02 20:11 ` Andi Kleen
2008-07-02 20:35 ` Andrew Morton
2008-07-02 20:51 ` Andi Kleen [this message]
2008-07-02 21:02 ` Andrew Morton
2008-07-02 21:07 ` Andi Kleen
2008-07-02 21:14 ` Andrew Morton
2008-07-06 17:18 ` Len Brown
2008-07-06 18:13 ` Andi Kleen
2008-07-06 18:52 ` Arjan van de Ven
2008-07-07 6:19 ` Andi Kleen
2008-07-07 7:03 ` Arjan van de Ven
2008-07-08 15:44 ` Thomas Renninger
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