Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <7181a47b-001c-0588-4102-1cfd8bead0ac@igalia.com>
Date:   Tue, 16 Aug 2022 17:12:33 -0300
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.12.0
Subject: Re: [PATCH v2 08/13] tracing: Improve panic/die notifiers
Content-Language: en-US
To:     Steven Rostedt <rostedt@goodmis.org>,
        Alan Stern <stern@rowland.harvard.edu>
Cc:     akpm@linux-foundation.org, bhe@redhat.com, pmladek@suse.com,
        kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-hyperv@vger.kernel.org, netdev@vger.kernel.org,
        x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net,
        halves@canonical.com, fabiomirmar@gmail.com,
        alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com,
        arnd@arndb.de, bp@alien8.de, corbet@lwn.net,
        d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com,
        dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org,
        mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com,
        jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org,
        luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com,
        paulmck@kernel.org, peterz@infradead.org, senozhatsky@chromium.org,
        tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com,
        will@kernel.org, Sergei Shtylyov <sergei.shtylyov@gmail.com>
References: <20220719195325.402745-1-gpiccoli@igalia.com>
 <20220719195325.402745-9-gpiccoli@igalia.com>
 <20220816101445.184ebb7c@gandalf.local.home>
 <YvuwUAGi6PvY5kmR@rowland.harvard.edu>
 <20220816115249.66cf8f15@gandalf.local.home>
From:   "Guilherme G. Piccoli" <gpiccoli@igalia.com>
In-Reply-To: <20220816115249.66cf8f15@gandalf.local.home>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 16/08/2022 12:52, Steven Rostedt wrote:
> On Tue, 16 Aug 2022 10:57:20 -0400
> Alan Stern <stern@rowland.harvard.edu> wrote:
> 
>>> static int trace_die_panic_handler(struct notifier_block *self,
>>> 				unsigned long ev, void *unused)
>>> {
>>> 	if (!ftrace_dump_on_oops)
>>> 		return NOTIFY_DONE;
>>>
>>> 	/* The die notifier requires DIE_OOPS to trigger */
>>> 	if (self == &trace_die_notifier && ev != DIE_OOPS)
>>> 		return NOTIFY_DONE;
>>>
>>> 	ftrace_dump(ftrace_dump_on_oops);
>>>
>>> 	return NOTIFY_DONE;
>>> }  
>>
>> Or better yet:
>>
>> 	if (ftrace_dump_on_oops) {
>>
>> 		/* The die notifier requires DIE_OOPS to trigger */
>> 		if (self != &trace_die_notifier || ev == DIE_OOPS)
>> 			ftrace_dump(ftrace_dump_on_oops);
>> 	}
>> 	return NOTIFY_DONE;
>>
> 
> That may be more consolidated but less easy to read and follow. This is far
> from a fast path.
> 
> As I maintain this bike-shed, I prefer the one I suggested ;-)
> 
> -- Steve

Perfect Steve and Alan, appreciate your suggestions!
I'll submit V3 using your change Steve - honestly, I'm not sure why in
the heck I put a goto there, yours is basically the same code, modulo
the goto heheh

A braino from me, for sure!
Cheers,


Guilherme