WSL2-Linux-Kernel/kernel/trace
Steven Rostedt (Red Hat) 524a386825 ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled
Some archs (specifically PowerPC), are sensitive with the ordering of
the enabling of the calls to function tracing and setting of the
function to use to be traced.

That is, update_ftrace_function() sets what function the ftrace_caller
trampoline should call. Some archs require this to be set before
calling ftrace_run_update_code().

Another bug was discovered, that ftrace_startup_sysctl() called
ftrace_run_update_code() directly. If the function the ftrace_caller
trampoline changes, then it will not be updated. Instead a call
to ftrace_startup_enable() should be called because it tests to see
if the callback changed since the code was disabled, and will
tell the arch to update appropriately. Most archs do not need this
notification, but PowerPC does.

The problem could be seen by the following commands:

 # echo 0 > /proc/sys/kernel/ftrace_enabled
 # echo function > /sys/kernel/debug/tracing/current_tracer
 # echo 1 > /proc/sys/kernel/ftrace_enabled
 # cat /sys/kernel/debug/tracing/trace

The trace will show that function tracing was not active.

Cc: stable@vger.kernel.org # 2.6.27+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2015-03-09 10:55:34 -04:00
..
Kconfig tracing: Remove function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST 2014-07-18 13:58:12 -04:00
Makefile Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2015-02-11 17:42:32 -08:00
blktrace.c Merge branch 'for-3.19/core' of git://git.kernel.dk/linux-block 2014-12-13 14:14:23 -08:00
ftrace.c ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled 2015-03-09 10:55:34 -04:00
power-traces.c PM / sleep: export suspend_resume trace event 2015-01-30 02:10:41 +01:00
ring_buffer.c ring-buffer: Do not wake up a splice waiter when page is not full 2015-02-11 07:41:42 -05:00
ring_buffer_benchmark.c trace: Use 64-bit timekeeping 2015-01-28 11:02:05 -05:00
rpm-traces.c PM / Runtime: Introduce trace points for tracing rpm_* functions 2011-09-27 22:53:27 +02:00
trace.c tracing: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
trace.h tracing: Make tracing_init_dentry_tr() static 2015-02-02 10:22:23 -05:00
trace_benchmark.c tracing: Only calculate stats of tracepoint benchmarks for 2^32 times 2014-06-06 00:41:38 -04:00
trace_benchmark.h tracing: Add tracepoint benchmark tracepoint 2014-05-29 22:49:54 -04:00
trace_branch.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_clock.c tracing: Fix wraparound problems in "uptime" trace clock 2014-07-21 09:56:12 -04:00
trace_entries.h tracing: Add trace_puts() for even faster trace_printk() tracing 2013-03-15 00:35:55 -04:00
trace_event_perf.c perf: Avoid horrible stack usage 2015-01-14 15:11:45 +01:00
trace_events.c The updates included in this pull request for ftrace are: 2015-02-12 08:37:41 -08:00
trace_events_filter.c tracing: Allow NOT to filter AND and OR clauses 2014-12-03 10:00:27 -05:00
trace_events_filter_test.h tracing/filter: Add startup tests for events filter 2011-08-19 14:35:59 -04:00
trace_events_trigger.c trace: Replace single-character seq_puts with seq_putc 2014-11-14 07:55:55 -05:00
trace_export.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_functions.c tracing/trivial: Fix typos and make an int into a bool 2014-11-20 10:05:36 -05:00
trace_functions_graph.c tracing: Use IS_ERR() check for return value of tracing_init_dentry() 2015-01-22 11:19:49 -05:00
trace_irqsoff.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_kdb.c KGDB/KDB fixes and cleanups 2015-01-09 20:51:10 -08:00
trace_kprobe.c The updates included in this pull request for ftrace are: 2015-02-12 08:37:41 -08:00
trace_mmiotrace.c tracing: Do not check return values of trace_seq_p*() for mmio tracer 2014-11-19 15:25:44 -05:00
trace_nop.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_output.c tracing: Add array printing helper 2015-01-28 10:34:47 -05:00
trace_output.h tracing: Add trace_seq_has_overflowed() and trace_handle_return() 2014-11-19 15:25:39 -05:00
trace_printk.c tracing: Use IS_ERR() check for return value of tracing_init_dentry() 2015-01-22 11:19:49 -05:00
trace_probe.c tracing/probes: Do not use return value of trace_seq_printf() 2014-11-19 15:25:44 -05:00
trace_probe.h kprobes, ftrace: Use NOKPROBE_SYMBOL macro in ftrace 2014-04-24 10:26:39 +02:00
trace_sched_switch.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_sched_wakeup.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_selftest.c Seems that Peter Zijlstra added a new check that is making old 2014-10-12 07:28:55 -04:00
trace_selftest_dynamic.c ftrace: Add self-tests for multiple function trace users 2011-05-18 19:24:51 -04:00
trace_seq.c tracing: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
trace_stack.c tracing: Use IS_ERR() check for return value of tracing_init_dentry() 2015-01-22 11:19:49 -05:00
trace_stat.c tracing: Use IS_ERR() check for return value of tracing_init_dentry() 2015-01-22 11:19:49 -05:00
trace_stat.h tracing/stat: Add stat_release() callback 2009-07-10 12:14:05 +02:00
trace_syscalls.c perf: Avoid horrible stack usage 2015-01-14 15:11:45 +01:00
trace_uprobe.c The updates included in this pull request for ftrace are: 2015-02-12 08:37:41 -08:00