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Date: Mon, 16 May 2016 15:02:52 -0700
From: Calvin Owens <calvinowens@fb.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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Subject: Re: [RFC][PATCH] printk: Add option to append kernel version to the
 dict
Message-ID: <20160516220252.GA2281534@devbig337.prn1.facebook.com>
References: <51047c0f6e86abcb9ee13f60653b6946f8fcfc99.1463172791.git.calvinowens@fb.com>
 <20160515063643.GA817@swordfish>
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On Sunday 05/15 at 15:36 +0900, Sergey Senozhatsky wrote:
> Hello,
> 
> On (05/13/16 13:58), Calvin Owens wrote:
> [..]
> > +#if defined(CONFIG_PRINTK_APPEND_UNAME)
> > +static ssize_t msg_print_ext_uname(char *buf, size_t size)
> > +{
> > +	return scnprintf(buf, size, " UNAME=%s\n", init_utsname()->release);
> > +}
> > +#else
> > +static ssize_t msg_print_ext_uname(char *buf, size_t size)
> > +{
> > +	return 0;
> > +}
> > +#endif
> > +
> >  /* /dev/kmsg - userspace message inject/listen interface */
> >  struct devkmsg_user {
> >  	u64 seq;
> > @@ -2305,6 +2317,8 @@ skip:
> >  						sizeof(ext_text) - ext_len,
> >  						log_dict(msg), msg->dict_len,
> >  						log_text(msg), msg->text_len);
> > +			ext_len += msg_print_ext_uname(ext_text + ext_len,
> > +						sizeof(ext_text) - ext_len);
> >  		}
> 
> what if there is no place left for init_utsname() after
> msg_print_ext_header() + msg_print_ext_body()?

It ends up being truncated, like either of the preceeding calls would.

> do you need init_utsname in every message? or just in WARN/ERR ones?

I need it added to anything which netconsole actually emits: so I could
filter based on loglevel here if you like.

Thanks,
Calvin

> 
> 	-ss