From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Vaneet Narang <v.narang@samsung.com>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Maninder Singh <maninder1.s@samsung.com>,
"sergey.senozhatsky@gmail.com" <sergey.senozhatsky@gmail.com>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
AMIT SAHRAWAT <a.sahrawat@samsung.com>,
PANKAJ MISHRA <pankaj.m@samsung.com>
Subject: Re: [PATCH 2/2] printk: make sure to print log on console.
Date: Fri, 1 Jun 2018 18:34:02 +0900 [thread overview]
Message-ID: <20180601093402.GB1841@jagdpanzerIV> (raw)
In-Reply-To: <20180601084236epcms5p5063cd250524f105a334d8d553302ab51@epcms5p5>
Hello,
On (06/01/18 14:12), Vaneet Narang wrote:
> > CPU0 CPU1
> >
> > set console verbose
> >
> > dump_backtrace()
> > {
> > // for (;;) print frames
> > printk("%pS\n", frame0);
> > printk("%pS\n", frame1);
> > printk("%pS\n", frame2);
> > printk("%pS\n", frame3);
> > ... console_loglevel = CONSOLE_LOGLEVEL_SILENT;
> > printk("%pS\n", frame12);
> > printk("%pS\n", frame13);
> > }
> >
>
> This is not printk issue, its printk usage issue. User need to handle this part using some protection.
>
> What we highlighted is issue related to printk, Where usage is correct
> but still printk can miss some logs due to printk design of asynchronous printing.
Yeah, I understand your example from the commit message. What I said was
"the patch does not fully address the problem". One way or another we still
can miss logs due to the very same problem: either console_loglevel
manipulation on another CPU, or printk_safe(), etc. May be there other
scenarios that are broken.
So if we are going to apply the patch [I don't have real objections, and
Petr seems to be fine], then I'd probably ask for a better commit messages.
Namely, I really want to document cases that are not addressed and are
still known to be broken.
-ss
next prev parent reply other threads:[~2018-06-01 9:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20180531102246epcas5p2f1cbc6ff217172e12e2f78bb88eb4a7e@epcas5p2.samsung.com>
2018-05-31 10:19 ` [PATCH 2/2] printk: make sure to print log on console Maninder Singh
2018-05-31 10:52 ` Sergey Senozhatsky
2018-05-31 12:21 ` Petr Mladek
2018-06-01 4:40 ` Sergey Senozhatsky
2018-06-01 8:53 ` Petr Mladek
2018-06-01 9:09 ` Petr Mladek
2018-06-01 9:37 ` Sergey Senozhatsky
2018-06-01 9:18 ` Sergey Senozhatsky
[not found] ` <CGME20180531102246epcas5p2f1cbc6ff217172e12e2f78bb88eb4a7e@epcms5p5>
2018-06-01 8:42 ` Vaneet Narang
2018-06-01 9:34 ` Sergey Senozhatsky [this message]
2018-05-31 13:27 ` Petr Mladek
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