linux/kernel/trace/ring_buffer.c, branch v4.11

ring-buffer: Have ring_buffer_iter_empty() return true when empty

2017-04-20T01:23:47Z

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. Cc: stable@vger.kernel.org Fixes: 651e22f2701b ("ring-buffer: Always reset iterator to reader page") Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Fix return value check in test_ringbuffer()

2017-04-05T13:36:52Z

In case of error, the function kthread_run() returns ERR_PTR() and never returns NULL. The NULL test in the return value check should be replaced with IS_ERR(). Link: http://lkml.kernel.org/r/1466184839-14927-1-git-send-email-weiyj_lk@163.com Cc: stable@vger.kernel.org Fixes: 6c43e554a ("ring-buffer: Add ring buffer startup selftest") Signed-off-by: Wei Yongjun Signed-off-by: Steven Rostedt (VMware)

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:27Z

We are going to split out of , which will have to be picked up from other headers and .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

Merge tag 'trace-v4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2016-12-15T21:49:34Z

Pull tracing updates from Steven Rostedt: "This release has a few updates: - STM can hook into the function tracer - Function filtering now supports more advance glob matching - Ftrace selftests updates and added tests - Softirq tag in traces now show only softirqs - ARM nop added to non traced locations at compile time - New trace_marker_raw file that allows for binary input - Optimizations to the ring buffer - Removal of kmap in trace_marker - Wakeup and irqsoff tracers now adhere to the set_graph_notrace file - Other various fixes and clean ups" * tag 'trace-v4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (42 commits) selftests: ftrace: Shift down default message verbosity kprobes/trace: Fix kprobe selftest for newer gcc tracing/kprobes: Add a helper method to return number of probe hits tracing/rb: Init the CPU mask on allocation tracing: Use SOFTIRQ_OFFSET for softirq dectection for more accurate results tracing/fgraph: Have wakeup and irqsoff tracers ignore graph functions too fgraph: Handle a case where a tracer ignores set_graph_notrace tracing: Replace kmap with copy_from_user() in trace_marker writing ftrace/x86_32: Set ftrace_stub to weak to prevent gcc from using short jumps to it tracing: Allow benchmark to be enabled at early_initcall() tracing: Have system enable return error if one of the events fail tracing: Do not start benchmark on boot up tracing: Have the reg function allow to fail ring-buffer: Force rb_end_commit() and rb_set_commit_to_write() inline ring-buffer: Froce rb_update_write_stamp() to be inlined ring-buffer: Force inline of hotpath helper functions tracing: Make __buffer_unlock_commit() always_inline tracing: Make tracepoint_printk a static_key ring-buffer: Always inline rb_event_data() ring-buffer: Make rb_reserve_next_event() always inlined ...

tracing/rb: Init the CPU mask on allocation

2016-12-12T22:57:26Z

Before commit b32614c03413 ("tracing/rb: Convert to hotplug state machine") the allocated cpumask was initialized to the mask of ONLINE or POSSIBLE CPUs. After the CPU hotplug changes the buffer initialisation moved to trace_rb_cpu_prepare() but I forgot to initially set the cpumask to zero. This is done now. Link: http://lkml.kernel.org/r/20161207133133.hzkcqfllxcdi3joz@linutronix.de Fixes: b32614c03413 ("tracing/rb: Convert to hotplug state machine") Reported-by: Tetsuo Handa Tested-by: Tetsuo Handa Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt

tracing/rb: Init the CPU mask on allocation

2016-12-07T13:36:21Z

Before commit b32614c03413 ("tracing/rb: Convert to hotplug state machine") the allocated cpumask was initialized to the mask of online or possible CPUs. After the CPU hotplug changes the buffer initialization moved to trace_rb_cpu_prepare() but the cpumask is allocated with alloc_cpumask() and therefor has random content. As a consequence the cpu buffers are not initialized and a later access dereferences a NULL pointer. Use zalloc_cpumask() instead so trace_rb_cpu_prepare() initializes the buffers properly. Fixes: b32614c03413 ("tracing/rb: Convert to hotplug state machine") Reported-by: Tetsuo Handa Signed-off-by: Sebastian Andrzej Siewior Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/20161207133133.hzkcqfllxcdi3joz@linutronix.de Signed-off-by: Thomas Gleixner

tracing/rb: Convert to hotplug state machine

2016-12-01T23:52:34Z

Install the callbacks via the state machine. The notifier in struct ring_buffer is replaced by the multi instance interface. Upon __ring_buffer_alloc() invocation, cpuhp_state_add_instance() will invoke the trace_rb_cpu_prepare() on each CPU. This callback may now fail. This means __ring_buffer_alloc() will fail and cleanup (like previously) and during a CPU up event this failure will not allow the CPU to come up. Signed-off-by: Sebastian Andrzej Siewior Cc: Steven Rostedt Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20161126231350.10321-7-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner

ring-buffer: Force rb_end_commit() and rb_set_commit_to_write() inline

2016-11-24T01:42:31Z

Both rb_end_commit() and rb_set_commit_to_write() are in the fast path of the ring buffer recording. Make sure they are always inlined. Link: http://lkml.kernel.org/r/20161121183700.GW26852@two.firstfloor.org Reported-by: Andi Kleen Signed-off-by: Steven Rostedt

ring-buffer: Froce rb_update_write_stamp() to be inlined

2016-11-24T01:38:39Z

The function rb_update_write_stamp() is in the hotpath of the ring buffer recording. Make sure that it is inlined as well. There's not many places that call it. Link: http://lkml.kernel.org/r/20161121183700.GW26852@two.firstfloor.org Reported-by: Andi Kleen Signed-off-by: Steven Rostedt

ring-buffer: Force inline of hotpath helper functions

2016-11-24T01:35:32Z

There's several small helper functions in ring_buffer.c that are used in the hot path. For some reason, even though they are marked inline, gcc tends not to enforce it. Make sure these functions are always inlined. Link: http://lkml.kernel.org/r/20161121183700.GW26852@two.firstfloor.org Reported-by: Andi Kleen Signed-off-by: Steven Rostedt