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Date: Mon, 27 Jan 2014 10:52:43 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...nel.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Tom Zanussi <tom.zanussi@...ux.intel.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] tracing: Documentation updates and minor bug fix
Linus,
The first two patches fix the debugfs README file to reflect better
the new features added to 3.14.
The third patch is a minor bugfix to the trace_puts() functions that
will crash the system if a developer adds one before the tracing system
is setup. It also affects trace_printk() if it has no arguments, as
the code will convert it to a trace_puts() as well. Note, this bug
will not affect unmodified kernels, as trace_printk() and trace_puts()
should only be used by developers for testing.
Please pull the latest trace-fixes-3.14 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-fixes-3.14
Tag SHA1: 14cc12e3c68e42cd2afb8f7e7beb7a570c22e2f8
Head SHA1: 3132e107d608f8753240d82d61303c500fd515b4
Steven Rostedt (Red Hat) (2):
tracing: Fix formatting of trace README file
tracing: Check if tracing is enabled in trace_puts()
Tom Zanussi (1):
tracing/README: Add event file usage to tracing mini-HOWTO
----
kernel/trace/trace.c | 113 ++++++++++++++++++++++++++++++++++++---------------
1 file changed, 81 insertions(+), 32 deletions(-)
---------------------------
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 20c755e..815c878 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -455,6 +455,9 @@ int __trace_puts(unsigned long ip, const char *str, int size)
unsigned long irq_flags;
int alloc;
+ if (unlikely(tracing_selftest_running || tracing_disabled))
+ return 0;
+
alloc = sizeof(*entry) + size + 2; /* possible \n added */
local_save_flags(irq_flags);
@@ -495,6 +498,9 @@ int __trace_bputs(unsigned long ip, const char *str)
unsigned long irq_flags;
int size = sizeof(struct bputs_entry);
+ if (unlikely(tracing_selftest_running || tracing_disabled))
+ return 0;
+
local_save_flags(irq_flags);
buffer = global_trace.trace_buffer.buffer;
event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
@@ -3519,60 +3525,103 @@ static const char readme_msg[] =
" instances\t\t- Make sub-buffers with: mkdir instances/foo\n"
"\t\t\t Remove sub-buffer with rmdir\n"
" trace_options\t\t- Set format or modify how tracing happens\n"
- "\t\t\t Disable an option by adding a suffix 'no' to the option name\n"
+ "\t\t\t Disable an option by adding a suffix 'no' to the\n"
+ "\t\t\t option name\n"
#ifdef CONFIG_DYNAMIC_FTRACE
"\n available_filter_functions - list of functions that can be filtered on\n"
- " set_ftrace_filter\t- echo function name in here to only trace these functions\n"
- " accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
- " modules: Can select a group via module\n"
- " Format: :mod:<module-name>\n"
- " example: echo :mod:ext3 > set_ftrace_filter\n"
- " triggers: a command to perform when function is hit\n"
- " Format: <function>:<trigger>[:count]\n"
- " trigger: traceon, traceoff\n"
- " enable_event:<system>:<event>\n"
- " disable_event:<system>:<event>\n"
+ " set_ftrace_filter\t- echo function name in here to only trace these\n"
+ "\t\t\t functions\n"
+ "\t accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+ "\t modules: Can select a group via module\n"
+ "\t Format: :mod:<module-name>\n"
+ "\t example: echo :mod:ext3 > set_ftrace_filter\n"
+ "\t triggers: a command to perform when function is hit\n"
+ "\t Format: <function>:<trigger>[:count]\n"
+ "\t trigger: traceon, traceoff\n"
+ "\t\t enable_event:<system>:<event>\n"
+ "\t\t disable_event:<system>:<event>\n"
#ifdef CONFIG_STACKTRACE
- " stacktrace\n"
+ "\t\t stacktrace\n"
#endif
#ifdef CONFIG_TRACER_SNAPSHOT
- " snapshot\n"
+ "\t\t snapshot\n"
#endif
- " example: echo do_fault:traceoff > set_ftrace_filter\n"
- " echo do_trap:traceoff:3 > set_ftrace_filter\n"
- " The first one will disable tracing every time do_fault is hit\n"
- " The second will disable tracing at most 3 times when do_trap is hit\n"
- " The first time do trap is hit and it disables tracing, the counter\n"
- " will decrement to 2. If tracing is already disabled, the counter\n"
- " will not decrement. It only decrements when the trigger did work\n"
- " To remove trigger without count:\n"
- " echo '!<function>:<trigger> > set_ftrace_filter\n"
- " To remove trigger with a count:\n"
- " echo '!<function>:<trigger>:0 > set_ftrace_filter\n"
+ "\t example: echo do_fault:traceoff > set_ftrace_filter\n"
+ "\t echo do_trap:traceoff:3 > set_ftrace_filter\n"
+ "\t The first one will disable tracing every time do_fault is hit\n"
+ "\t The second will disable tracing at most 3 times when do_trap is hit\n"
+ "\t The first time do trap is hit and it disables tracing, the\n"
+ "\t counter will decrement to 2. If tracing is already disabled,\n"
+ "\t the counter will not decrement. It only decrements when the\n"
+ "\t trigger did work\n"
+ "\t To remove trigger without count:\n"
+ "\t echo '!<function>:<trigger> > set_ftrace_filter\n"
+ "\t To remove trigger with a count:\n"
+ "\t echo '!<function>:<trigger>:0 > set_ftrace_filter\n"
" set_ftrace_notrace\t- echo function name in here to never trace.\n"
- " accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
- " modules: Can select a group via module command :mod:\n"
- " Does not accept triggers\n"
+ "\t accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+ "\t modules: Can select a group via module command :mod:\n"
+ "\t Does not accept triggers\n"
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_TRACER
- " set_ftrace_pid\t- Write pid(s) to only function trace those pids (function)\n"
+ " set_ftrace_pid\t- Write pid(s) to only function trace those pids\n"
+ "\t\t (function)\n"
#endif
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
" set_graph_function\t- Trace the nested calls of a function (function_graph)\n"
" max_graph_depth\t- Trace a limited depth of nested calls (0 is unlimited)\n"
#endif
#ifdef CONFIG_TRACER_SNAPSHOT
- "\n snapshot\t\t- Like 'trace' but shows the content of the static snapshot buffer\n"
- "\t\t\t Read the contents for more information\n"
+ "\n snapshot\t\t- Like 'trace' but shows the content of the static\n"
+ "\t\t\t snapshot buffer. Read the contents for more\n"
+ "\t\t\t information\n"
#endif
#ifdef CONFIG_STACK_TRACER
" stack_trace\t\t- Shows the max stack trace when active\n"
" stack_max_size\t- Shows current max stack size that was traced\n"
- "\t\t\t Write into this file to reset the max size (trigger a new trace)\n"
+ "\t\t\t Write into this file to reset the max size (trigger a\n"
+ "\t\t\t new trace)\n"
#ifdef CONFIG_DYNAMIC_FTRACE
- " stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace traces\n"
+ " stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace\n"
+ "\t\t\t traces\n"
#endif
#endif /* CONFIG_STACK_TRACER */
+ " events/\t\t- Directory containing all trace event subsystems:\n"
+ " enable\t\t- Write 0/1 to enable/disable tracing of all events\n"
+ " events/<system>/\t- Directory containing all trace events for <system>:\n"
+ " enable\t\t- Write 0/1 to enable/disable tracing of all <system>\n"
+ "\t\t\t events\n"
+ " filter\t\t- If set, only events passing filter are traced\n"
+ " events/<system>/<event>/\t- Directory containing control files for\n"
+ "\t\t\t <event>:\n"
+ " enable\t\t- Write 0/1 to enable/disable tracing of <event>\n"
+ " filter\t\t- If set, only events passing filter are traced\n"
+ " trigger\t\t- If set, a command to perform when event is hit\n"
+ "\t Format: <trigger>[:count][if <filter>]\n"
+ "\t trigger: traceon, traceoff\n"
+ "\t enable_event:<system>:<event>\n"
+ "\t disable_event:<system>:<event>\n"
+#ifdef CONFIG_STACKTRACE
+ "\t\t stacktrace\n"
+#endif
+#ifdef CONFIG_TRACER_SNAPSHOT
+ "\t\t snapshot\n"
+#endif
+ "\t example: echo traceoff > events/block/block_unplug/trigger\n"
+ "\t echo traceoff:3 > events/block/block_unplug/trigger\n"
+ "\t echo 'enable_event:kmem:kmalloc:3 if nr_rq > 1' > \\\n"
+ "\t events/block/block_unplug/trigger\n"
+ "\t The first disables tracing every time block_unplug is hit.\n"
+ "\t The second disables tracing the first 3 times block_unplug is hit.\n"
+ "\t The third enables the kmalloc event the first 3 times block_unplug\n"
+ "\t is hit and has value of greater than 1 for the 'nr_rq' event field.\n"
+ "\t Like function triggers, the counter is only decremented if it\n"
+ "\t enabled or disabled tracing.\n"
+ "\t To remove a trigger without a count:\n"
+ "\t echo '!<trigger> > <system>/<event>/trigger\n"
+ "\t To remove a trigger with a count:\n"
+ "\t echo '!<trigger>:0 > <system>/<event>/trigger\n"
+ "\t Filters can be ignored when removing a trigger.\n"
;
static ssize_t
--
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