From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: sergey.senozhatsky.work@gmail.com, dvyukov@google.com,
pmladek@suse.com, sergey.senozhatsky@gmail.com,
syzkaller@googlegroups.com, rostedt@goodmis.org,
fengguang.wu@intel.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org
Subject: Re: [PATCH] printk: inject caller information into the body of message
Date: Thu, 17 May 2018 20:21:35 +0900 [thread overview]
Message-ID: <20180517112135.GB20796@jagdpanzerIV> (raw)
In-Reply-To: <201805112058.AAB05258.HJQFFOMFOVtOSL@I-love.SAKURA.ne.jp>
On (05/11/18 20:58), Tetsuo Handa wrote:
[..]
> - if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf)) {
> + if (nr_ext_console_drivers) {
> + cont_flush();
> + return false;
> + }
> +
> + /* Inject before memcpy() in order to avoid overflow. */
> + if (!cont.len)
> + text = printk_inject_caller_info(text, &len);
> +
> + /* If the line gets too long, split it up in separate records. */
> + if (cont.len + len > sizeof(cont.buf)) {
> cont_flush();
> return false;
> }
> @@ -1820,6 +1860,9 @@ static size_t log_output(int facility, int level, enum log_flags lflags, const c
> return text_len;
> }
>
> + /* Inject caller info. */
> + text = printk_inject_caller_info(text, &text_len);
> +
> /* Store it in the record log */
> return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len);
> }
[..]
I think this is slightly intrusive. I understand that you want to avoid
struct printk_log modification, let's try to see if we have any other
options.
Dunno...
For instance, can we store context tracking info as a extended record
data? We have that dict/dict_len thing. So may we can store tracking
info there? Extended records will appear on the serial console /* if
console supports extended data */ or can be read in via devkmsg_read().
Any other options?
> #include "internal.h"
>
> @@ -83,6 +84,17 @@ static __printf(2, 0) int printk_safe_log_store(struct printk_safe_seq_buf *s,
[..]
> len = atomic_read(&s->len);
> @@ -102,7 +114,15 @@ static __printf(2, 0) int printk_safe_log_store(struct printk_safe_seq_buf *s,
> smp_rmb();
>
> va_copy(ap, args);
> - add = vscnprintf(s->buffer + len, sizeof(s->buffer) - len, fmt, ap);
> + if (printk_caller_info) {
> + struct va_format vaf = { .fmt = fmt, .va = &ap };
> +
> + add = scnprintf(s->buffer + len, sizeof(s->buffer) - len,
> + "(%c%u) %pV", c, v, &vaf);
> + } else {
> + add = vscnprintf(s->buffer + len, sizeof(s->buffer) - len,
> + fmt, ap);
> + }
A bit of a silly question - do we want to modify printk_safe at this
point? With this implementation printk_safe entries will have two context
info-s attached: one from original printk_safe_log_store and another one
from printk_safe_flush->log_store. I suspect that adding context info in
printk_safe_log_store is, probably, not really needed. We flush printk_safe
from irq work on the CPU that issued unsafe printk, so part of the context
info will be valid if you append context info only in printk log_store - at
least the correct smp_processor_id.
-ss
next prev parent reply other threads:[~2018-05-17 11:21 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <201804232233.CIC65675.OJSOMFQOFFHVtL@I-love.SAKURA.ne.jp>
[not found] ` <CACT4Y+boyw_Qy=y-iTnsKZrtTgF0Hk3nHN_xtqUdX4etgiYDQw@mail.gmail.com>
2018-04-24 1:33 ` printk feature for syzbot? Sergey Senozhatsky
2018-04-24 14:40 ` Steven Rostedt
2018-04-26 10:06 ` Petr Mladek
2018-05-10 4:22 ` Sergey Senozhatsky
2018-05-10 11:30 ` Petr Mladek
2018-05-10 12:11 ` Sergey Senozhatsky
2018-05-10 14:22 ` Steven Rostedt
2018-05-10 14:50 ` Tetsuo Handa
2018-05-11 1:45 ` Sergey Senozhatsky
[not found] ` <201805110238.w4B2cIGH079602@www262.sakura.ne.jp>
2018-05-11 6:21 ` Sergey Senozhatsky
2018-05-11 9:17 ` Dmitry Vyukov
2018-05-11 9:50 ` Sergey Senozhatsky
2018-05-11 11:58 ` [PATCH] printk: inject caller information into the body of message Tetsuo Handa
2018-05-17 11:21 ` Sergey Senozhatsky [this message]
2018-05-17 11:52 ` Sergey Senozhatsky
2018-05-18 12:15 ` Petr Mladek
2018-05-18 12:25 ` Dmitry Vyukov
2018-05-18 12:54 ` Petr Mladek
2018-05-18 13:08 ` Dmitry Vyukov
2018-05-24 2:21 ` Sergey Senozhatsky
2018-05-23 10:19 ` Tetsuo Handa
2018-05-24 2:14 ` Sergey Senozhatsky
2018-05-26 6:36 ` Dmitry Vyukov
2018-06-20 5:44 ` Dmitry Vyukov
2018-06-20 8:31 ` Sergey Senozhatsky
2018-06-20 8:45 ` Dmitry Vyukov
2018-06-20 9:06 ` Sergey Senozhatsky
2018-06-20 9:18 ` Sergey Senozhatsky
2018-06-20 9:31 ` Dmitry Vyukov
2018-06-20 11:07 ` Sergey Senozhatsky
2018-06-20 11:32 ` Dmitry Vyukov
2018-06-20 13:06 ` Sergey Senozhatsky
2018-06-22 13:06 ` Tetsuo Handa
2018-06-25 1:41 ` Sergey Senozhatsky
2018-06-25 9:36 ` Dmitry Vyukov
2018-06-27 10:29 ` Tetsuo Handa
2018-09-10 11:20 ` Alexander Potapenko
2018-09-12 6:53 ` Sergey Senozhatsky
2018-09-12 16:05 ` Steven Rostedt
2018-09-13 7:12 ` Sergey Senozhatsky
2018-09-13 12:26 ` Petr Mladek
2018-09-13 14:28 ` Sergey Senozhatsky
2018-09-14 1:22 ` Steven Rostedt
2018-09-14 2:15 ` Sergey Senozhatsky
2018-09-14 6:57 ` Sergey Senozhatsky
2018-09-14 10:37 ` Tetsuo Handa
2018-09-14 11:50 ` Sergey Senozhatsky
2018-09-14 12:03 ` Tetsuo Handa
2018-09-14 12:22 ` Sergey Senozhatsky
2018-09-19 11:02 ` Tetsuo Handa
2018-09-24 8:11 ` Tetsuo Handa
2018-09-27 16:10 ` Tetsuo Handa
2018-09-28 9:02 ` Sergey Senozhatsky
2018-09-28 9:09 ` Sergey Senozhatsky
2018-09-28 11:01 ` Tetsuo Handa
2018-09-29 10:51 ` Sergey Senozhatsky
2018-09-29 11:15 ` Tetsuo Handa
2018-10-01 2:37 ` Sergey Senozhatsky
2018-10-01 2:58 ` Sergey Senozhatsky
2018-10-01 11:21 ` Tetsuo Handa
2018-10-02 6:38 ` Sergey Senozhatsky
2018-10-08 10:31 ` Tetsuo Handa
2018-10-08 16:03 ` Petr Mladek
2018-10-08 20:48 ` Tetsuo Handa
2018-10-09 14:52 ` Petr Mladek
2018-10-09 21:19 ` Tetsuo Handa
2018-10-10 10:14 ` Tetsuo Handa
2018-10-11 10:20 ` Tetsuo Handa
2018-10-11 13:47 ` Steven Rostedt
2018-10-08 15:43 ` Petr Mladek
2018-09-28 8:56 ` Sergey Senozhatsky
2018-09-28 11:21 ` Tetsuo Handa
2018-09-29 11:13 ` Sergey Senozhatsky
2018-09-29 11:39 ` Tetsuo Handa
2018-10-01 5:52 ` Sergey Senozhatsky
2018-10-01 8:37 ` Sergey Senozhatsky
2018-10-01 18:06 ` Steven Rostedt
2018-09-14 1:12 ` Steven Rostedt
2018-09-14 1:55 ` Sergey Senozhatsky
2018-06-21 8:29 ` Sergey Senozhatsky
2018-06-20 9:30 ` Dmitry Vyukov
2018-06-20 11:19 ` Sergey Senozhatsky
2018-06-20 11:25 ` Dmitry Vyukov
2018-06-20 11:37 ` Fengguang Wu
2018-06-20 12:31 ` Dmitry Vyukov
2018-06-20 12:41 ` Fengguang Wu
2018-06-20 12:45 ` Dmitry Vyukov
2018-06-20 12:48 ` Fengguang Wu
2018-05-11 13:37 ` printk feature for syzbot? Steven Rostedt
2018-05-15 5:20 ` Sergey Senozhatsky
2018-05-15 14:39 ` Steven Rostedt
2018-05-11 11:02 ` [PATCH] printk: fix possible reuse of va_list variable Tetsuo Handa
2018-05-11 11:27 ` Sergey Senozhatsky
2018-05-17 11:57 ` Petr Mladek
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