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| author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2014-12-12 22:27:10 -0500 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2014-12-15 10:17:38 -0500 |
| commit | 0daa2302968c13b657118d6ac92471f8fd2f3f28 (patch) | |
| tree | 8bea68f7bbeab6521c11c01f55b5660082eeedf6 /kernel/sysctl.c | |
| parent | 5f893b2639b21ffe6834b1aebba392c37d2b83f9 (diff) | |
| download | lwn-0daa2302968c13b657118d6ac92471f8fd2f3f28.tar.gz lwn-0daa2302968c13b657118d6ac92471f8fd2f3f28.zip | |
tracing: Add tp_printk cmdline to have tracepoints go to printk()
Add the kernel command line tp_printk option that will have tracepoints
that are active sent to printk() as well as to the trace buffer.
Passing "tp_printk" will activate this. To turn it off, the sysctl
/proc/sys/kernel/tracepoint_printk can have '0' echoed into it. Note,
this only works if the cmdline option is used. Echoing 1 into the sysctl
file without the cmdline option will have no affect.
Note, this is a dangerous option. Having high frequency tracepoints send
their data to printk() can possibly cause a live lock. This is another
reason why this is only active if the command line option is used.
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/sysctl.c')
| -rw-r--r-- | kernel/sysctl.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 4aada6d9fe74..bb50c2187194 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -622,6 +622,13 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "tracepoint_printk", + .data = &tracepoint_printk, + .maxlen = sizeof(tracepoint_printk), + .mode = 0644, + .proc_handler = proc_dointvec, + }, #endif #ifdef CONFIG_KEXEC { |