diff options
| author | Petr Mladek <pmladek@suse.com> | 2016-05-20 17:00:36 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-20 17:58:30 -0700 |
| commit | b522deabc6f18e4f938d93a84f345f2cbf3347d1 (patch) | |
| tree | 297c5f13ffcb3521ea57f7f44bf78f6319de098d /kernel/printk/printk.c | |
| parent | 42a0bb3f71383b457a7db362f1c69e7afb96732b (diff) | |
| download | linux-b522deabc6f18e4f938d93a84f345f2cbf3347d1.tar.bz2 | |
printk/nmi: warn when some message has been lost in NMI context
We could not resize the temporary buffer in NMI context. Let's warn if
a message is lost.
This is rather theoretical. printk() should not be used in NMI. The
only sensible use is when we want to print backtrace from all CPUs. The
current buffer should be enough for this purpose.
[akpm@linux-foundation.org: whitespace fixlet]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jiri Kosina <jkosina@suse.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/printk/printk.c')
| -rw-r--r-- | kernel/printk/printk.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 71eba0607034..e38579d730f4 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1617,6 +1617,7 @@ asmlinkage int vprintk_emit(int facility, int level, unsigned long flags; int this_cpu; int printed_len = 0; + int nmi_message_lost; bool in_sched = false; /* cpu currently holding logbuf_lock in this function */ static unsigned int logbuf_cpu = UINT_MAX; @@ -1667,6 +1668,15 @@ asmlinkage int vprintk_emit(int facility, int level, strlen(recursion_msg)); } + nmi_message_lost = get_nmi_message_lost(); + if (unlikely(nmi_message_lost)) { + text_len = scnprintf(textbuf, sizeof(textbuf), + "BAD LUCK: lost %d message(s) from NMI context!", + nmi_message_lost); + printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0, + NULL, 0, textbuf, text_len); + } + /* * The printf needs to come first; we need the syslog * prefix which might be passed-in as a parameter. |