linux-kernel - Re: [PATCH V2] panic: add support to update panic

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Date:   Fri, 27 Oct 2017 13:00:06 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Jeetesh Burman <jburman@...dia.com>, keescook@...omium.org,
        linux-kernel@...r.kernel.org, bbasu@...dia.com,
        Andrew Morton <akpm@...ux-foundation.org>, robh+dt@...nel.org,
        frowand.list@...il.com, devicetree@...r.kernel.org
Subject: Re: [PATCH V2] panic: add support to update panic_timeout via DT

[+devicetree, Rob, Frank]

On Fri, Oct 27, 2017 at 06:53:14PM +0900, Sergey Senozhatsky wrote:
> Cc-ing Andrew on this
> 
> 
> v1: lkml.kernel.org/r/1509076662-22253-1-git-send-email-jburman@...dia.com
>     lkml.kernel.org/r/20171027080006.GA609@...erII.localdomain
> 
> v2: lkml.kernel.org/r/1509097165-15695-1-git-send-email-jburman@...dia.com
> 
> 	-ss
> 
> On (10/27/17 15:09), Jeetesh Burman wrote:
> > Add support to set 'panic_timeout' value via dtb to have
> > control from device tree. This makes sense when you have
> > multiple platforms support from same defconfig and
> > differentiated only through device tree blob.
> > The patch will check for panic time out value coming
> > from dtb if it exists, otherwise continues with
> > defconfig provided option.

I will let Rob and Frank chime in - as far as I am concerned
you are (ab)using DT to configure a Linux kernel specific internal
variable and that's certainly not what DT is there for.

Lorenzo
 
> > Signed-off-by: Jeetesh Burman <jburman@...dia.com>
> > ---
> >  kernel/panic.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kernel/panic.c b/kernel/panic.c
> > index bdd18af..b487331 100644
> > --- a/kernel/panic.c
> > +++ b/kernel/panic.c
> > @@ -27,6 +27,7 @@
> >  #include <linux/console.h>
> >  #include <linux/bug.h>
> >  #include <linux/ratelimit.h>
> > +#include <linux/of.h>
> >  
> >  #define PANIC_TIMER_STEP 100
> >  #define PANIC_BLINK_SPD 18
> > @@ -482,9 +483,15 @@ static u64 oops_id;
> >  
> >  static int init_oops_id(void)
> >  {
> > -	if (!oops_id)
> > +	struct device_node *np;
> > +
> > +	if (!oops_id) {
> > +		np = of_find_node_by_name(NULL, "panic_timeout");
> > +		if (np)
> > +			of_property_read_u32(np, "panic-timeout-value",
> > +							&panic_timeout);
> >  		get_random_bytes(&oops_id, sizeof(oops_id));
> > -	else
> > +	} else
> >  		oops_id++;
> >  
> >  	return 0;
> > -- 
> > 2.1.4
> >