linux-kernel - Re: [PATCH 2/7] powerpc/traps: Return early in show_signal

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Date:   Wed, 25 Jul 2018 17:31:35 -0300
From:   Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
To:     LEROY Christophe <christophe.leroy@....fr>
Cc:     linuxppc-dev@...ts.ozlabs.org, "Tobin C . Harding" <me@...in.cc>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
        Simon Guo <wei.guo.simon@...il.com>,
        Paul Mackerras <paulus@...ba.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Michael Neuling <mikey@...ling.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Cyril Bur <cyrilbur@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Balbir Singh <bsingharora@...il.com>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        "Alastair D'Silva" <alastair@...ilva.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/7] powerpc/traps: Return early in show_signal_msg()

Hi, Christophe.

On Wed, Jul 25, 2018 at 05:42:28PM +0200, LEROY Christophe wrote:
> Murilo Opsfelder Araujo <muriloo@...ux.ibm.com> a écrit :
> 
> > Modify logic of show_signal_msg() to return early, if possible.  Replace
> > printk_ratelimited() by printk() and a default rate limit burst to limit
> > displaying unhandled signals messages.
> 
> Can you explain more the benefits of this change ?

Mainly is to improve readability of the function.

The conditions to display the message were coupled together in one
single `if` statement.

Besides that, patch 5/7 adds a call to print_vma_addr(), which is not
aware of any rate limit - it simply calls printk().

So splitting out the rate limit check outside show_signal_msg() makes it
easier to the caller decide if it wants to respect a printk rate limit
or not.

Cheers
Murilo