Messages in this thread | | | Date | Fri, 18 Nov 2011 19:44:06 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH v2] printk: add console output tracing |
| |
On Thu, Nov 17, 2011 at 04:21:08PM +0100, Johannes Berg wrote: > From: Johannes Berg <johannes.berg@intel.com> > > Add a printk.console trace point to record any printk > messages into the trace, regardless of the current > console loglevel. This can help correlate (existing) > printk debugging with other tracing. > > Signed-off-by: Johannes Berg <johannes.berg@intel.com> > --- > v2: remove extra file > > include/trace/events/printk.h | 44 ++++++++++++++++++++++++++++++++++++++++++ > kernel/printk.c | 5 ++++ > 2 files changed, 49 insertions(+) > > --- /dev/null 1970-01-01 00:00:00.000000000 +0000 > +++ b/include/trace/events/printk.h 2011-11-16 23:18:35.000000000 +0100 > @@ -0,0 +1,44 @@ > +#undef TRACE_SYSTEM > +#define TRACE_SYSTEM printk > + > +#if !defined(_TRACE_PRINTK_H) || defined(TRACE_HEADER_MULTI_READ) > +#define _TRACE_PRINTK_H > + > +#include <linux/tracepoint.h> > + > +TRACE_EVENT_CONDITION(console, > + TP_PROTO(const char *log_buf, unsigned start, unsigned end, > + unsigned log_buf_len), > + > + TP_ARGS(log_buf, start, end, log_buf_len), > + > + TP_CONDITION(start != end), > + > + TP_STRUCT__entry( > + __dynamic_array(char, msg, > + ((end - start + log_buf_len) & > + (log_buf_len - 1)) + 1)
Is all that care about log_buf_len necessary? It seems that printk ensures that log_end - con_start never exceeds log_buf_len, looking at emit_log_char()
Thanks.
> + ), > + > + TP_fast_assign( > + if ((start & (log_buf_len - 1)) > (end & (log_buf_len - 1))) { > + memcpy(__get_dynamic_array(msg), > + log_buf + (start & (log_buf_len - 1)), > + log_buf_len - (start & (log_buf_len - 1))); > + memcpy((char *)__get_dynamic_array(msg) + > + log_buf_len - (start & (log_buf_len - 1)), > + log_buf, end & (log_buf_len - 1)); > + } else > + memcpy(__get_dynamic_array(msg), > + log_buf + (start & (log_buf_len - 1)), > + (end - start + log_buf_len) & (log_buf_len - 1)); > + ((char *)__get_dynamic_array(msg))[(end - start + log_buf_len) & > + (log_buf_len - 1)] = 0; > + ), > + > + TP_printk("%s", __get_str(msg)) > +); > +#endif /* _TRACE_PRINTK_H */ > + > +/* This part must be outside protection */ > +#include <trace/define_trace.h> > --- a/kernel/printk.c 2011-11-16 22:25:43.000000000 +0100 > +++ b/kernel/printk.c 2011-11-17 16:19:19.000000000 +0100 > @@ -44,6 +44,9 @@ > > #include <asm/uaccess.h> > > +#define CREATE_TRACE_POINTS > +#include <trace/events/printk.h> > + > /* > * Architectures can override it: > */ > @@ -542,6 +545,8 @@ MODULE_PARM_DESC(ignore_loglevel, "ignor > static void _call_console_drivers(unsigned start, > unsigned end, int msg_log_level) > { > + trace_console(&LOG_BUF(0), start, end, log_buf_len); > + > if ((msg_log_level < console_loglevel || ignore_loglevel) && > console_drivers && start != end) { > if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { > >
| |