linux-toradex.git/kernel/trace/ring_buffer.c, branch v5.13-rc3

tracing: Remove unused argument from "ring_buffer_time_stamp()

2021-04-01T18:18:32+00:00

The "cpu" parameter is not being used by the function.

Link: https://lkml.kernel.org/r/20210329130331.199402-1-y.karadz@gmail.com

Signed-off-by: Yordan Karadzhov (VMware) 
Signed-off-by: Steven Rostedt (VMware)

tracing: Fix various typos in comments

2021-03-23T18:08:18+00:00

Fix ~59 single-word typos in the tracing code comments, and fix
the grammar in a handful of places.

Link: https://lore.kernel.org/r/20210322224546.GA1981273@gmail.com
Link: https://lkml.kernel.org/r/20210323174935.GA4176821@gmail.com

Reviewed-by: Randy Dunlap 
Signed-off-by: Ingo Molnar 
Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Add verifier for using ring_buffer_event_time_stamp()

2021-03-18T16:58:26+00:00

The ring_buffer_event_time_stamp() must be only called by an event that has
not been committed yet, and is on the buffer that is passed in. This was
used to help debug converting the histogram logic over to using the new
time stamp code, and was proven to be very useful.

Add a verifier that can check that this is the case, and extra WARN_ONs to
catch unexpected use cases.

Link: https://lkml.kernel.org/r/20210316164113.987294354@goodmis.org

Reviewed-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Allow ring_buffer_event_time_stamp() to return time stamp of all events

2021-03-18T16:58:26+00:00

Currently, ring_buffer_event_time_stamp() only returns an accurate time
stamp of the event if it has an absolute extended time stamp attached to
it. To make it more robust, use the event_stamp() in case the event does
not have an absolute value attached to it.

This will allow ring_buffer_event_time_stamp() to be used in more cases
than just histograms, and it will also allow histograms to not require
including absolute values all the time.

Link: https://lkml.kernel.org/r/20210316164113.704830885@goodmis.org

Reviewed-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Add a event_stamp to cpu_buffer for each level of nesting

2021-03-18T16:58:25+00:00

Add a place to save the current event time stamp for each level of nesting.
This will be used to retrieve the time stamp of the current event before it
is committed.

Link: https://lkml.kernel.org/r/20210316164113.399089673@goodmis.org

Reviewed-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Separate out internal use of ring_buffer_event_time_stamp()

2021-03-18T16:58:25+00:00

The exported use of ring_buffer_event_time_stamp() is going to become
different than how it is used internally. Move the internal logic out into a
static function called rb_event_time_stamp(), and have the internal callers
call that instead.

Link: https://lkml.kernel.org/r/20210316164113.257790481@goodmis.org

Reviewed-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Add a little more information and a WARN when time stamp going backwards is detected

2021-03-04T14:45:17+00:00

When the CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS is enabled, and the time
stamps are detected as not being valid, it reports information about the
write stamp, but does not show the before_stamp which is still useful
information. Also, it should give a warning once, such that tests detect
this happening.

Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Force before_stamp and write_stamp to be different on discard

2021-03-04T14:45:17+00:00

Part of the logic of the new time stamp code depends on the before_stamp and
the write_stamp to be different if the write_stamp does not match the last
event on the buffer, as it will be used to calculate the delta of the next
event written on the buffer.

The discard logic depends on this, as the next event to come in needs to
inject a full timestamp as it can not rely on the last event timestamp in
the buffer because it is unknown due to events after it being discarded. But
by changing the write_stamp back to the time before it, it forces the next
event to use a full time stamp, instead of relying on it.

The issue came when a full time stamp was used for the event, and
rb_time_delta() returns zero in that case. The update to the write_stamp
(which subtracts delta) made it not change. Then when the event is removed
from the buffer, because the before_stamp and write_stamp still match, the
next event written would calculate its delta from the write_stamp, but that
would be wrong as the write_stamp is of the time of the event that was
discarded.

In the case that the delta change being made to write_stamp is zero, set the
before_stamp to zero as well, and this will force the next event to inject a
full timestamp and not use the current write_stamp.

Cc: stable@vger.kernel.org
Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp")
Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Drop unneeded check in ring_buffer_resize()

2021-02-02T22:02:06+00:00

Remove the cpumask check, as we has done it at the beginning of
the function.
Also fix a typo. s/also the on the/also on the/

Link: https://lkml.kernel.org/r/20201224144634.3210-1-hqjagain@gmail.com

Signed-off-by: Qiujun Huang 
Signed-off-by: Steven Rostedt (VMware)

ring-buffer: Remove cpu_buffer argument from the rb_inc_page()

2021-02-02T22:02:06+00:00

The cpu_buffer argument is not used inside the rb_inc_page() after
commit 3adc54fa82a6 ("ring-buffer: make the buffer a true circular link
list").
And cpu_buffer argument is not used inside the two functions too,
rb_is_head_page/rb_set_list_to_head.

Link: https://lkml.kernel.org/r/20201225140356.23008-1-hqjagain@gmail.com

Signed-off-by: Qiujun Huang 
Signed-off-by: Steven Rostedt (VMware)