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
Unified · Split
| @@ -455,6 +455,9 @@ int __trace_puts(unsigned long ip, const char *str, int size) · 454 unmodified lines | ||
| 455 | 455 | unsigned long irq_flags; |
| 456 | 456 | int alloc; |
| 457 | 457 | |
| 458 | + if (unlikely(tracing_selftest_running || tracing_disabled)) | |
| 459 | + return 0; | |
| 460 | + | |
| 458 | 461 | alloc = sizeof(*entry) + size + 2; /* possible \n added */ |
| 459 | 462 | |
| 460 | 463 | local_save_flags(irq_flags); |
| @@ -495,6 +498,9 @@ int __trace_bputs(unsigned long ip, const char *str) · 34 unmodified lines | ||
| 495 | 498 | unsigned long irq_flags; |
| 496 | 499 | int size = sizeof(struct bputs_entry); |
| 497 | 500 | |
| 501 | + if (unlikely(tracing_selftest_running || tracing_disabled)) | |
| 502 | + return 0; | |
| 503 | + | |
| 498 | 504 | local_save_flags(irq_flags); |
| 499 | 505 | buffer = global_trace.trace_buffer.buffer; |
| 500 | 506 | event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size, |
| @@ -3519,60 +3525,103 @@ static const char readme_msg[] = · 3018 unmodified lines | ||
| 3519 | 3525 | " instances\t\t- Make sub-buffers with: mkdir instances/foo\n" |
| 3520 | 3526 | "\t\t\t Remove sub-buffer with rmdir\n" |
| 3521 | 3527 | " trace_options\t\t- Set format or modify how tracing happens\n" |
| 3522 | − "\t\t\t Disable an option by adding a suffix 'no' to the option name\n" | |
| 3528 | + "\t\t\t Disable an option by adding a suffix 'no' to the\n" | |
| 3529 | + "\t\t\t option name\n" | |
| 3523 | 3530 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 3524 | 3531 | "\n available_filter_functions - list of functions that can be filtered on\n" |
| 3525 | − " set_ftrace_filter\t- echo function name in here to only trace these functions\n" | |
| 3526 | − " accepts: func_full_name, *func_end, func_begin*, *func_middle*\n" | |
| 3527 | − " modules: Can select a group via module\n" | |
| 3528 | − " Format: :mod:<module-name>\n" | |
| 3529 | − " example: echo :mod:ext3 > set_ftrace_filter\n" | |
| 3530 | − " triggers: a command to perform when function is hit\n" | |
| 3531 | − " Format: <function>:<trigger>[:count]\n" | |
| 3532 | − " trigger: traceon, traceoff\n" | |
| 3533 | − " enable_event:<system>:<event>\n" | |
| 3534 | − " disable_event:<system>:<event>\n" | |
| 3532 | + " set_ftrace_filter\t- echo function name in here to only trace these\n" | |
| 3533 | + "\t\t\t functions\n" | |
| 3534 | + "\t accepts: func_full_name, *func_end, func_begin*, *func_middle*\n" | |
| 3535 | + "\t modules: Can select a group via module\n" | |
| 3536 | + "\t Format: :mod:<module-name>\n" | |
| 3537 | + "\t example: echo :mod:ext3 > set_ftrace_filter\n" | |
| 3538 | + "\t triggers: a command to perform when function is hit\n" | |
| 3539 | + "\t Format: <function>:<trigger>[:count]\n" | |
| 3540 | + "\t trigger: traceon, traceoff\n" | |
| 3541 | + "\t\t enable_event:<system>:<event>\n" | |
| 3542 | + "\t\t disable_event:<system>:<event>\n" | |
| 3535 | 3543 | #ifdef CONFIG_STACKTRACE |
| 3536 | − " stacktrace\n" | |
| 3544 | + "\t\t stacktrace\n" | |
| 3537 | 3545 | #endif |
| 3538 | 3546 | #ifdef CONFIG_TRACER_SNAPSHOT |
| 3539 | − " snapshot\n" | |
| 3547 | + "\t\t snapshot\n" | |
| 3540 | 3548 | #endif |
| 3541 | − " example: echo do_fault:traceoff > set_ftrace_filter\n" | |
| 3542 | − " echo do_trap:traceoff:3 > set_ftrace_filter\n" | |
| 3543 | − " The first one will disable tracing every time do_fault is hit\n" | |
| 3544 | − " The second will disable tracing at most 3 times when do_trap is hit\n" | |
| 3545 | − " The first time do trap is hit and it disables tracing, the counter\n" | |
| 3546 | − " will decrement to 2. If tracing is already disabled, the counter\n" | |
| 3547 | − " will not decrement. It only decrements when the trigger did work\n" | |
| 3548 | − " To remove trigger without count:\n" | |
| 3549 | − " echo '!<function>:<trigger> > set_ftrace_filter\n" | |
| 3550 | − " To remove trigger with a count:\n" | |
| 3551 | − " echo '!<function>:<trigger>:0 > set_ftrace_filter\n" | |
| 3549 | + "\t example: echo do_fault:traceoff > set_ftrace_filter\n" | |
| 3550 | + "\t echo do_trap:traceoff:3 > set_ftrace_filter\n" | |
| 3551 | + "\t The first one will disable tracing every time do_fault is hit\n" | |
| 3552 | + "\t The second will disable tracing at most 3 times when do_trap is hit\n" | |
| 3553 | + "\t The first time do trap is hit and it disables tracing, the\n" | |
| 3554 | + "\t counter will decrement to 2. If tracing is already disabled,\n" | |
| 3555 | + "\t the counter will not decrement. It only decrements when the\n" | |
| 3556 | + "\t trigger did work\n" | |
| 3557 | + "\t To remove trigger without count:\n" | |
| 3558 | + "\t echo '!<function>:<trigger> > set_ftrace_filter\n" | |
| 3559 | + "\t To remove trigger with a count:\n" | |
| 3560 | + "\t echo '!<function>:<trigger>:0 > set_ftrace_filter\n" | |
| 3552 | 3561 | " set_ftrace_notrace\t- echo function name in here to never trace.\n" |
| 3553 | − " accepts: func_full_name, *func_end, func_begin*, *func_middle*\n" | |
| 3554 | − " modules: Can select a group via module command :mod:\n" | |
| 3555 | − " Does not accept triggers\n" | |
| 3562 | + "\t accepts: func_full_name, *func_end, func_begin*, *func_middle*\n" | |
| 3563 | + "\t modules: Can select a group via module command :mod:\n" | |
| 3564 | + "\t Does not accept triggers\n" | |
| 3556 | 3565 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
| 3557 | 3566 | #ifdef CONFIG_FUNCTION_TRACER |
| 3558 | − " set_ftrace_pid\t- Write pid(s) to only function trace those pids (function)\n" | |
| 3567 | + " set_ftrace_pid\t- Write pid(s) to only function trace those pids\n" | |
| 3568 | + "\t\t (function)\n" | |
| 3559 | 3569 | #endif |
| 3560 | 3570 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 3561 | 3571 | " set_graph_function\t- Trace the nested calls of a function (function_graph)\n" |
| 3562 | 3572 | " max_graph_depth\t- Trace a limited depth of nested calls (0 is unlimited)\n" |
| 3563 | 3573 | #endif |
| 3564 | 3574 | #ifdef CONFIG_TRACER_SNAPSHOT |
| 3565 | − "\n snapshot\t\t- Like 'trace' but shows the content of the static snapshot buffer\n" | |
| 3566 | − "\t\t\t Read the contents for more information\n" | |
| 3575 | + "\n snapshot\t\t- Like 'trace' but shows the content of the static\n" | |
| 3576 | + "\t\t\t snapshot buffer. Read the contents for more\n" | |
| 3577 | + "\t\t\t information\n" | |
| 3567 | 3578 | #endif |
| 3568 | 3579 | #ifdef CONFIG_STACK_TRACER |
| 3569 | 3580 | " stack_trace\t\t- Shows the max stack trace when active\n" |
| 3570 | 3581 | " stack_max_size\t- Shows current max stack size that was traced\n" |
| 3571 | − "\t\t\t Write into this file to reset the max size (trigger a new trace)\n" | |
| 3582 | + "\t\t\t Write into this file to reset the max size (trigger a\n" | |
| 3583 | + "\t\t\t new trace)\n" | |
| 3572 | 3584 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 3573 | − " stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace traces\n" | |
| 3585 | + " stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace\n" | |
| 3586 | + "\t\t\t traces\n" | |
| 3574 | 3587 | #endif |
| 3575 | 3588 | #endif /* CONFIG_STACK_TRACER */ |
| 3589 | + " events/\t\t- Directory containing all trace event subsystems:\n" | |
| 3590 | + " enable\t\t- Write 0/1 to enable/disable tracing of all events\n" | |
| 3591 | + " events/<system>/\t- Directory containing all trace events for <system>:\n" | |
| 3592 | + " enable\t\t- Write 0/1 to enable/disable tracing of all <system>\n" | |
| 3593 | + "\t\t\t events\n" | |
| 3594 | + " filter\t\t- If set, only events passing filter are traced\n" | |
| 3595 | + " events/<system>/<event>/\t- Directory containing control files for\n" | |
| 3596 | + "\t\t\t <event>:\n" | |
| 3597 | + " enable\t\t- Write 0/1 to enable/disable tracing of <event>\n" | |
| 3598 | + " filter\t\t- If set, only events passing filter are traced\n" | |
| 3599 | + " trigger\t\t- If set, a command to perform when event is hit\n" | |
| 3600 | + "\t Format: <trigger>[:count][if <filter>]\n" | |
| 3601 | + "\t trigger: traceon, traceoff\n" | |
| 3602 | + "\t enable_event:<system>:<event>\n" | |
| 3603 | + "\t disable_event:<system>:<event>\n" | |
| 3604 | +#ifdef CONFIG_STACKTRACE | |
| 3605 | + "\t\t stacktrace\n" | |
| 3606 | +#endif | |
| 3607 | +#ifdef CONFIG_TRACER_SNAPSHOT | |
| 3608 | + "\t\t snapshot\n" | |
| 3609 | +#endif | |
| 3610 | + "\t example: echo traceoff > events/block/block_unplug/trigger\n" | |
| 3611 | + "\t echo traceoff:3 > events/block/block_unplug/trigger\n" | |
| 3612 | + "\t echo 'enable_event:kmem:kmalloc:3 if nr_rq > 1' > \\\n" | |
| 3613 | + "\t events/block/block_unplug/trigger\n" | |
| 3614 | + "\t The first disables tracing every time block_unplug is hit.\n" | |
| 3615 | + "\t The second disables tracing the first 3 times block_unplug is hit.\n" | |
| 3616 | + "\t The third enables the kmalloc event the first 3 times block_unplug\n" | |
| 3617 | + "\t is hit and has value of greater than 1 for the 'nr_rq' event field.\n" | |
| 3618 | + "\t Like function triggers, the counter is only decremented if it\n" | |
| 3619 | + "\t enabled or disabled tracing.\n" | |
| 3620 | + "\t To remove a trigger without a count:\n" | |
| 3621 | + "\t echo '!<trigger> > <system>/<event>/trigger\n" | |
| 3622 | + "\t To remove a trigger with a count:\n" | |
| 3623 | + "\t echo '!<trigger>:0 > <system>/<event>/trigger\n" | |
| 3624 | + "\t Filters can be ignored when removing a trigger.\n" | |
| 3576 | 3625 | ; |
| 3577 | 3626 | |
| 3578 | 3627 | static ssize_t |