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| 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/nmi.c | |
| parent | 42a0bb3f71383b457a7db362f1c69e7afb96732b (diff) | |
| download | linux-0-day-b522deabc6f18e4f938d93a84f345f2cbf3347d1.tar.gz linux-0-day-b522deabc6f18e4f938d93a84f345f2cbf3347d1.tar.xz | |
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/nmi.c')
| -rw-r--r-- | kernel/printk/nmi.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/printk/nmi.c b/kernel/printk/nmi.c index 303cf0d15e575..572f949222307 100644 --- a/kernel/printk/nmi.c +++ b/kernel/printk/nmi.c @@ -39,6 +39,7 @@ */ DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default; static int printk_nmi_irq_ready; +atomic_t nmi_message_lost; #define NMI_LOG_BUF_LEN (4096 - sizeof(atomic_t) - sizeof(struct irq_work)) @@ -64,8 +65,10 @@ static int vprintk_nmi(const char *fmt, va_list args) again: len = atomic_read(&s->len); - if (len >= sizeof(s->buffer)) + if (len >= sizeof(s->buffer)) { + atomic_inc(&nmi_message_lost); return 0; + } /* * Make sure that all old data have been read before the buffer was |