linux/kernel/trace
Josef Bacik 4ce97dbf50 trace: Fix epoll hang when we race with new entries
Epoll on trace_pipe can sometimes hang in a weird case.  If the ring buffer is
empty when we set waiters_pending but an event shows up exactly at that moment
we can miss being woken up by the ring buffers irq work.  Since
ring_buffer_empty() is inherently racey we will sometimes think that the buffer
is not empty.  So we don't get woken up and we don't think there are any events
even though there were some ready when we added the watch, which makes us hang.
This patch fixes this by making sure that we are actually on the wait list
before we set waiters_pending, and add a memory barrier to make sure
ring_buffer_empty() is going to be correct.

Link: http://lkml.kernel.org/p/1408989581-23727-1-git-send-email-jbacik@fb.com

Cc: stable@vger.kernel.org # 3.10+
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-08-25 20:18:11 -04:00
..
Kconfig tracing: Remove function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST 2014-07-18 13:58:12 -04:00
Makefile tracing: Move the trace_seq_* functions into its own trace_seq.c file 2014-07-01 07:13:35 -04:00
blktrace.c Most of the changes were largely clean ups, and some documentation. 2014-04-03 10:26:31 -07:00
ftrace.c ftrace: Use current addr when converting to nop in __ftrace_replace_code() 2014-08-22 21:04:35 -04:00
power-traces.c PM / tracing: remove deprecated power trace API 2013-01-26 00:39:12 +01:00
ring_buffer.c trace: Fix epoll hang when we race with new entries 2014-08-25 20:18:11 -04:00
ring_buffer_benchmark.c trace: Replace hardcoding of 19 with MAX_NICE 2014-02-27 12:41:03 +01:00
rpm-traces.c PM / Runtime: Introduce trace points for tracing rpm_* functions 2011-09-27 22:53:27 +02:00
trace.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-05 17:46:42 -07:00
trace.h tracing: let user specify tracing_thresh after selecting function_graph 2014-07-18 15:48:52 -04:00
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: Update event filters for multibuffer 2013-11-05 16:50:20 -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: Check permission only for parent tracepoint event 2014-07-28 10:01:38 +02:00
trace_events.c Oleg Nesterov did several clean ups with the tracing filter code. 2014-08-04 12:02:48 -07:00
trace_events_filter.c tracing: Kill "filter_string" arg of replace_preds() 2014-07-16 14:58:53 -04:00
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 tracing: Use rcu_dereference_sched() for trace event triggers 2014-05-02 23:12:42 -04:00
trace_export.c tracing: Fix anonymous unions in struct ftrace_event_call 2014-04-09 20:02:55 -04:00
trace_functions.c tracing: Remove mock up poll wait function 2014-04-30 08:40:05 -04:00
trace_functions_graph.c tracing: Convert local function_graph functions to static 2014-07-18 21:16:06 -04:00
trace_irqsoff.c tracing: Allow irq/preempt tracers to be used by instances 2014-04-21 13:59:29 -04:00
trace_kdb.c tracing: Consolidate max_tr into main trace_array structure 2013-03-15 00:35:40 -04:00
trace_kprobe.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-06-12 19:18:49 -07:00
trace_mmiotrace.c tracing: Update event filters for multibuffer 2013-11-05 16:50:20 -05:00
trace_nop.c tracing: Remove mock up poll wait function 2014-04-30 08:40:05 -04:00
trace_output.c tracing: Add trace_seq_buffer_ptr() helper function 2014-07-01 07:13:39 -04:00
trace_output.h tracing: Make trace_seq_putmem_hex() more robust 2014-07-01 07:13:37 -04:00
trace_printk.c tracing: Add __tracepoint_string() to export string pointers 2013-07-26 13:39:44 -04:00
trace_probe.c kprobes, ftrace: Use NOKPROBE_SYMBOL macro in ftrace 2014-04-24 10:26:39 +02:00
trace_probe.h kprobes, ftrace: Use NOKPROBE_SYMBOL macro in ftrace 2014-04-24 10:26:39 +02:00
trace_sched_switch.c tracing: Update event filters for multibuffer 2013-11-05 16:50:20 -05:00
trace_sched_wakeup.c tracing: Remove mock up poll wait function 2014-04-30 08:40:05 -04:00
trace_selftest.c tracing: Add static to local functions 2014-04-21 14:00:46 -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: Remove trace_seq_reserve() 2014-07-01 07:13:37 -04:00
trace_stack.c tracing: Print max callstack on stacktrace bug 2014-06-02 16:43:49 -04:00
trace_stat.c trace/trace_stat: use rbtree postorder iteration helper instead of opencoding 2013-11-05 16:01:47 -05:00
trace_stat.h tracing/stat: Add stat_release() callback 2009-07-10 12:14:05 +02:00
trace_syscalls.c tracing: Consolidate event trigger code 2014-01-09 21:20:07 -05:00
trace_uprobe.c tracing/uprobes: Kill the dead TRACE_EVENT_FL_USE_CALL_FILTER logic 2014-07-16 14:25:19 -04:00