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authorTom Zanussi <tom.zanussi@linux.intel.com>2019-03-31 18:48:15 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-04-02 18:24:06 -0400
commit8a062902be725f647dc8da532b04d836546a369a (patch)
treed80858410ea2a8d53c16d4852ba297dd3afffe21 /kernel/trace/trace.h
parentf45d1225adb0479478cee989e2ae2d7d2c62b31b (diff)
downloadlinux-8a062902be725f647dc8da532b04d836546a369a.tar.bz2
tracing: Add tracing error log
Introduce a new ftrace file, tracing/error_log, for ftrace commands to log errors. This is useful for allowing more complex commands such as hist trigger and kprobe_event commands to point out specifically where something may have gone wrong without forcing them to resort to more ad hoc methods such as tacking error messages onto existing output files. To log a tracing error, call the event_log_err() function, passing it a location string describing where it came from e.g. kprobe_events or system:event, the command that caused the error, an array of static error strings describing errors and an index within that array which describes the specific error, along with the position to place the error caret. Reading the log displays the last (currently) 8 errors logged in the following format: [timestamp] <loc>: error: <static error text> Command: <command that caused the error> ^ Memory for the error log isn't allocated unless there has been a trace event error, and the error log can be cleared and have its memory freed by writing the empty string in truncation mode to it: # echo > tracing/error_log. Link: http://lkml.kernel.org/r/0c2c82571fd38c5f3a88ca823627edff250e9416.1554072478.git.tom.zanussi@linux.intel.com Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Suggested-by: Masami Hiramatsu <mhiramat@kernel.org> Improvements-suggested-by: Steve Rostedt <rostedt@goodmis.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace.h')
-rw-r--r--kernel/trace/trace.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d80cee49e0eb..b711edbef7e7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1884,6 +1884,10 @@ extern ssize_t trace_parse_run_command(struct file *file,
const char __user *buffer, size_t count, loff_t *ppos,
int (*createfn)(int, char**));
+extern unsigned int err_pos(char *cmd, const char *str);
+extern void tracing_log_err(const char *loc, const char *cmd,
+ const char **errs, u8 type, u8 pos);
+
/*
* Normal trace_printk() and friends allocates special buffers
* to do the manipulation, as well as saves the print formats