kernel/linux.git/samples/trace_events/trace-events-sample.c, branch linux-7.0.y

tracing: Add __cpumask to denote a trace event field that is a cpumask_t

2022-11-24T00:08:30+00:00

The trace events have a __bitmask field that can be used for anything that requires bitmasks. Although currently it is only used for CPU masks, it could be used in the future for any type of bitmasks. There is some user space tooling that wants to know if a field is a CPU mask and not just some random unsigned long bitmask. Introduce "__cpumask()" helper functions that work the same as the current __bitmask() helpers but displays in the format file: field:__data_loc cpumask_t *[] mask; offset:36; size:4; signed:0; Instead of: field:__data_loc unsigned long[] mask; offset:32; size:4; signed:0; The main difference is the type. Instead of "unsigned long" it is "cpumask_t *". Note, this type field needs to be a real type in the __dynamic_array() logic that both __cpumask and__bitmask use, but the comparison field requires it to be a scalar type whereas cpumask_t is a structure (non-scalar). But everything works when making it a pointer. Valentin added changes to remove the need of passing in "nr_bits" and the __cpumask will always use nr_cpumask_bits as its size. Link: https://lkml.kernel.org/r/20221014080456.1d32b989@rorschach.local.home Requested-by: Valentin Schneider Reviewed-by: Valentin Schneider Signed-off-by: Valentin Schneider Signed-off-by: Steven Rostedt (Google)

tracing: Add example and documentation for new __vstring() macro

2022-07-24T23:11:17+00:00

Update the sample trace events to include an example that uses the new __vstring() helpers for TRACE_EVENTS. Link: https://lkml.kernel.org/r/20220715175555.16375a3b@gandalf.local.home Signed-off-by: Steven Rostedt (Google)

samples/trace_event: Add '__rel_loc' using sample event

2021-12-06T20:37:22+00:00

Add '__rel_loc' using sample event for testing. User can use this for testing purpose. There is no reason to use this macro from the kernel. Link: https://lkml.kernel.org/r/163757343050.510314.2876529802471645178.stgit@devnote2 Cc: Beau Belgrave Cc: Namhyung Kim Cc: Tom Zanussi Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

sched/core: Provide a pointer to the valid CPU mask

2019-06-03T09:49:37+00:00

In commit: 4b53a3412d66 ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper") the tsk_nr_cpus_allowed() wrapper was removed. There was not much difference in !RT but in RT we used this to implement migrate_disable(). Within a migrate_disable() section the CPU mask is restricted to single CPU while the "normal" CPU mask remains untouched. As an alternative implementation Ingo suggested to use: struct task_struct { const cpumask_t *cpus_ptr; cpumask_t cpus_mask; }; with t->cpus_ptr = &t->cpus_mask; In -RT we then can switch the cpus_ptr to: t->cpus_ptr = &cpumask_of(task_cpu(p)); in a migration disabled region. The rules are simple: - Code that 'uses' ->cpus_allowed would use the pointer. - Code that 'modifies' ->cpus_allowed would use the direct mask. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner Cc: Linus Torvalds Cc: Peter Zijlstra Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de Signed-off-by: Ingo Molnar

treewide: Add SPDX license identifier for more missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which: - Have no license information of any form - Have MODULE_LICENCE("GPL*") inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

Fix tracing sample code warning.

2017-10-28T03:35:31+00:00

Commit 6575257c60e1 ("tracing/samples: Fix creation and deletion of simple_thread_fn creation") introduced a new warning due to using a boolean as a counter. Just make it "int". Fixes: 6575257c60e1 ("tracing/samples: Fix creation and deletion of simple_thread_fn creation") Cc: Steven Rostedt Signed-off-by: Linus Torvalds

tracing/samples: Fix creation and deletion of simple_thread_fn creation

2017-10-17T18:55:24+00:00

Commit 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT()") added template examples for all the events. It created a DEFINE_EVENT_FN() example which reused the foo_bar_reg and foo_bar_unreg functions. Enabling both the TRACE_EVENT_FN() and DEFINE_EVENT_FN() example trace events caused the foo_bar_reg to be called twice, creating the test thread twice. The foo_bar_unreg would remove it only once, even if it was called multiple times, leaving a thread existing when the module is unloaded, causing an oops. Add a ref count and allow foo_bar_reg() and foo_bar_unreg() be called by multiple trace events. Cc: stable@vger.kernel.org Fixes: 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT()") Signed-off-by: Steven Rostedt (VMware)

sched/core: Remove the tsk_cpus_allowed() wrapper

2017-03-02T07:42:24+00:00

So the original intention of tsk_cpus_allowed() was to 'future-proof' the field - but it's pretty ineffectual at that, because half of the code uses ->cpus_allowed directly ... Also, the wrapper makes the code longer than the original expression! So just get rid of it. This also shrinks a bit. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

tracing: Have the reg function allow to fail

2016-12-09T14:13:30+00:00

Some tracepoints have a registration function that gets enabled when the tracepoint is enabled. There may be cases that the registraction function must fail (for example, can't allocate enough memory). In this case, the tracepoint should also fail to register, otherwise the user would not know why the tracepoint is not working. Cc: David Howells Cc: Seiji Aguchi Cc: Anton Blanchard Cc: Mathieu Desnoyers Signed-off-by: Steven Rostedt

tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT()

2015-02-09T23:05:51+00:00

Add to samples/trace_events/ the macros DECLARE_EVENT_CLASS() and DEFINE_EVENT() and recommend using them over multiple TRACE_EVENT() macros if the multiple events have the same format. Signed-off-by: Steven Rostedt