Steven Rostedt (VMware) a2a67e53f9 ring-buffer: Have ring_buffer_iter_empty() return true when empty ... commit 78f7a45dac upstream. I noticed that reading the snapshot file when it is empty no longer gives a status. It suppose to show the status of the snapshot buffer as well as how to allocate and use it. For example: ># cat snapshot # tracer: nop # # # * Snapshot is allocated * # # Snapshot commands: # echo 0 > snapshot : Clears and frees snapshot buffer # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated. # Takes a snapshot of the main buffer. # echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free) # (Doesn't have to be '2' works with any number that # is not a '0' or '1') But instead it just showed an empty buffer: ># cat snapshot # tracer: nop # # entries-in-buffer/entries-written: 0/0 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | What happened was that it was using the ring_buffer_iter_empty() function to see if it was empty, and if it was, it showed the status. But that function was returning false when it was empty. The reason was that the iter header page was on the reader page, and the reader page was empty, but so was the buffer itself. The check only tested to see if the iter was on the commit page, but the commit page was no longer pointing to the reader page, but as all pages were empty, the buffer is also. Fixes: 651e22f270 ("ring-buffer: Always reset iterator to reader page") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2017-04-27 09:09:31 +02:00
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blktrace.c
bpf_trace.c
ftrace.c	ftrace: Fix removing of second function probe	2017-04-21 09:30:06 +02:00
Kconfig
Makefile	Makefile: Mute warning for __builtin_return_address(>0) for tracing only	2016-09-30 10:18:35 +02:00
power-traces.c
ring_buffer_benchmark.c
ring_buffer.c	ring-buffer: Have ring_buffer_iter_empty() return true when empty	2017-04-27 09:09:31 +02:00
rpm-traces.c
trace_benchmark.c
trace_benchmark.h
trace_branch.c
trace_clock.c
trace_entries.h
trace_event_perf.c
trace_events_filter_test.h
trace_events_filter.c
trace_events_trigger.c
trace_events.c	tracing: Don't display trigger file for events that can't be enabled	2016-05-11 11:21:13 +02:00
trace_export.c
trace_functions_graph.c	fgraph: Handle a case where a tracer ignores set_graph_notrace	2017-01-09 08:07:50 +01:00
trace_functions.c
trace_irqsoff.c	tracing: Have preempt(irqs)off trace preempt disabled functions	2016-04-12 09:08:59 -07:00
trace_kdb.c
trace_kprobe.c
trace_mmiotrace.c
trace_nop.c
trace_output.c
trace_output.h
trace_printk.c	tracing: Handle NULL formats in hold_module_trace_bprintk_format()	2016-07-27 09:47:32 -07:00
trace_probe.c
trace_probe.h
trace_sched_switch.c
trace_sched_wakeup.c
trace_selftest_dynamic.c
trace_selftest.c
trace_seq.c
trace_stack.c
trace_stat.c
trace_stat.h
trace_syscalls.c
trace_uprobe.c
trace.c	tracing: Allocate the snapshot buffer before enabling probe	2017-04-27 09:09:31 +02:00
trace.h