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The first two patches fix the debugfs README file to reflect better

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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.
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Merge tag 'trace-fixes-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "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"

* tag 'trace-fixes-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Check if tracing is enabled in trace_puts()
  tracing: Fix formatting of trace README file
  tracing/README: Add event file usage to tracing mini-HOWTO
This commit is contained in:
Linus Torvalds 2014-01-27 08:22:30 -08:00
commit ba635f8cd2
1 changed files with 81 additions and 32 deletions
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113
kernel/trace/trace.c
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@ -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