tracing: Remove TRACE_EVENT_FL_FILTERED logic

After commit dcb0b5575d24 ("tracing: Remove TRACE_EVENT_FL_USE_CALL_FILTER
logic"), no one's going to set the TRACE_EVENT_FL_FILTERED or change the
cal

tracing: Remove TRACE_EVENT_FL_FILTERED logic

After commit dcb0b5575d24 ("tracing: Remove TRACE_EVENT_FL_USE_CALL_FILTER
logic"), no one's going to set the TRACE_EVENT_FL_FILTERED or change the
call->filter, so remove related logic.

Link: https://lore.kernel.org/[email protected]
Signed-off-by: Zheng Yejian <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

tracing/hwlat: Fix a race during cpuhp processing

The cpuhp online/offline processing race also exists in percpu-mode hwlat
tracer in theory, apply the fix too. That is:

T1

tracing/hwlat: Fix a race during cpuhp processing

The cpuhp online/offline processing race also exists in percpu-mode hwlat
tracer in theory, apply the fix too. That is:

T1 | T2
[CPUHP_ONLINE] | cpu_device_down()
hwlat_hotplug_workfn() |
| cpus_write_lock()
| takedown_cpu(1)
| cpus_write_unlock()
[CPUHP_OFFLINE] |
cpus_read_lock() |
start_kthread(1) |
cpus_read_unlock() |

Cc: [email protected]
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Link: https://lore.kernel.org/[email protected]
Fixes: ba998f7d9531 ("trace/hwlat: Support hotplug operations")
Signed-off-by: Wei Li <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

tracing: Remove extra space at the end of hwlat_detector/mode

Space is printed after each mode value including the last one:
$ echo \"$(sudo cat /sys/kernel/tracing/hwlat_detector/mode)\"
"none [rou

tracing: Remove extra space at the end of hwlat_detector/mode

Space is printed after each mode value including the last one:
$ echo \"$(sudo cat /sys/kernel/tracing/hwlat_detector/mode)\"
"none [round-robin] per-cpu "

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Link: https://lore.kernel.org/linux-trace-kernel/[email protected]

Cc: Masami Hiramatsu <[email protected]>
Fixes: 8fa826b7344d ("trace/hwlat: Implement the mode config option")
Signed-off-by: Mikhail Kobuk <[email protected]>
Reviewed-by: Alexey Khoroshilov <[email protected]>
Acked-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

tracing/hwlat: Replace sched_setaffinity with set_cpus_allowed_ptr

There is a problem with the behavior of hwlat in a container,
resulting in incorrect output. A warning message is generated:
"cpuma

tracing/hwlat: Replace sched_setaffinity with set_cpus_allowed_ptr

There is a problem with the behavior of hwlat in a container,
resulting in incorrect output. A warning message is generated:
"cpumask changed while in round-robin mode, switching to mode none",
and the tracing_cpumask is ignored. This issue arises because
the kernel thread, hwlatd, is not a part of the container, and
the function sched_setaffinity is unable to locate it using its PID.
Additionally, the task_struct of hwlatd is already known.
Ultimately, the function set_cpus_allowed_ptr achieves
the same outcome as sched_setaffinity, but employs task_struct
instead of PID.

Test case:

# cd /sys/kernel/tracing
# echo 0 > tracing_on
# echo round-robin > hwlat_detector/mode
# echo hwlat > current_tracer
# unshare --fork --pid bash -c 'echo 1 > tracing_on'
# dmesg -c

Actual behavior:

[573502.809060] hwlat_detector: cpumask changed while in round-robin mode, switching to mode none

Link: https://lore.kernel.org/linux-trace-kernel/[email protected]

Cc: Masami Hiramatsu <[email protected]>
Fixes: 0330f7aa8ee63 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Costa Shulyupin <[email protected]>
Acked-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

trace/hwlat: Do not start per-cpu thread if it is already running

The hwlatd tracer will end up starting multiple per-cpu threads with
the following script:

#!/bin/sh
cd /sys/kernel/debug/t

trace/hwlat: Do not start per-cpu thread if it is already running

The hwlatd tracer will end up starting multiple per-cpu threads with
the following script:

#!/bin/sh
cd /sys/kernel/debug/tracing
echo 0 > tracing_on
echo hwlat > current_tracer
echo per-cpu > hwlat_detector/mode
echo 100000 > hwlat_detector/width
echo 200000 > hwlat_detector/window
echo 1 > tracing_on

To fix the issue, check if the hwlatd thread for the cpu is already
running, before starting a new one. Along with the previous patch, this
avoids running multiple instances of the same CPU thread on the system.

Link: https://lore.kernel.org/all/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]

Cc: [email protected]
Fixes: f46b16520a087 ("trace/hwlat: Implement the per-cpu mode")
Signed-off-by: Tero Kristo <[email protected]>
Acked-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

trace/hwlat: Do not wipe the contents of per-cpu thread data

Do not wipe the contents of the per-cpu kthread data when starting the
tracer, as this will completely forget about already running insta

trace/hwlat: Do not wipe the contents of per-cpu thread data

Do not wipe the contents of the per-cpu kthread data when starting the
tracer, as this will completely forget about already running instances
and can later start new additional per-cpu threads.

Link: https://lore.kernel.org/all/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]

Cc: [email protected]
Fixes: f46b16520a087 ("trace/hwlat: Implement the per-cpu mode")
Signed-off-by: Tero Kristo <[email protected]>
Acked-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

trace/hwlat: make use of the helper function kthread_run_on_cpu()

Replace kthread_create_on_cpu/wake_up_process() with kthread_run_on_cpu()
to simplify the code.

Link: https://lkml.kernel.org/r/202

trace/hwlat: make use of the helper function kthread_run_on_cpu()

Replace kthread_create_on_cpu/wake_up_process() with kthread_run_on_cpu()
to simplify the code.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Cai Huoqing <[email protected]>
Cc: Bernard Metzler <[email protected]>
Cc: Daniel Bristot de Oliveira <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Doug Ledford <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Josh Triplett <[email protected]>
Cc: Lai Jiangshan <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: "Paul E . McKenney" <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

tracing/hwlat: Make some internal symbols static

The sparse tool complains as follows:

kernel/trace/trace_hwlat.c:82:27: warning: symbol 'hwlat_single_cpu_data' was not declared. Should it be stati

tracing/hwlat: Make some internal symbols static

The sparse tool complains as follows:

kernel/trace/trace_hwlat.c:82:27: warning: symbol 'hwlat_single_cpu_data' was not declared. Should it be static?
kernel/trace/trace_hwlat.c:83:1: warning: symbol '__pcpu_scope_hwlat_per_cpu_data' was not declared. Should it be static?

This symbol is not used outside of trace_hwlat.c, so this commit
marks it static.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Wang ShaoBo <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

tracing: Disable "other" permission bits in the tracefs files

When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for

tracing: Disable "other" permission bits in the tracefs files

When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for admins who
want to define a group for accessing tracefs and not having to first
disable all the permission bits for "other" in the file system.

As tracing can leak sensitive information, it should never by default
allowing all users access. An admin can still set the permission bits for
others to have access, which may be useful for creating a honeypot and
seeing who takes advantage of it and roots the machine.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

tracing: Replace deprecated CPU-hotplug functions.

The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and

tracing: Replace deprecated CPU-hotplug functions.

The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().

Replace deprecated CPU-hotplug functions with the official version.
The behavior remains unchanged.

Link: https://lkml.kernel.org/r/[email protected]

Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Acked-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

tracing: Quiet smp_processor_id() use in preemptable warning in hwlat

The hardware latency detector (hwlat) has a mode that it runs one thread
across CPUs. The logic to move from the currently runni

tracing: Quiet smp_processor_id() use in preemptable warning in hwlat

The hardware latency detector (hwlat) has a mode that it runs one thread
across CPUs. The logic to move from the currently running CPU to the next
one in the list does a smp_processor_id() to find where it currently is.
Unfortunately, it's done with preemption enabled, and this triggers a
warning for using smp_processor_id() in a preempt enabled section.

As it is only using smp_processor_id() to get information on where it
currently is in order to simply move it to the next CPU, it doesn't really
care if it got moved in the mean time. It will simply balance out later if
such a case arises.

Switch smp_processor_id() to raw_smp_processor_id() to quiet that warning.

Link: https://lkml.kernel.org/r/[email protected]

Acked-by: Daniel Bristot de Oliveira <[email protected]>
Fixes: 8fa826b7344d ("trace/hwlat: Implement the mode config option")
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Support hotplug operations

Enable and disable hwlat thread during cpu hotplug online
and offline operations, respectivelly.

Link: https://lore.kernel.org/linux-doc/20210621134636.5b332

trace/hwlat: Support hotplug operations

Enable and disable hwlat thread during cpu hotplug online
and offline operations, respectivelly.

Link: https://lore.kernel.org/linux-doc/[email protected]/
Link: https://lkml.kernel.org/r/52012d25ea35491a0f8088b947864d8df8e25157.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Suggested-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Protect kdata->kthread with get/put_online_cpus

In preparation to the hotplug support, protect kdata->kthread
with get/put_online_cpus() to avoid concurrency with hotplug
operations.

L

trace/hwlat: Protect kdata->kthread with get/put_online_cpus

In preparation to the hotplug support, protect kdata->kthread
with get/put_online_cpus() to avoid concurrency with hotplug
operations.

Link: https://lore.kernel.org/linux-doc/[email protected]/
Link: https://lkml.kernel.org/r/8bdb2a56f46abfd301d6fffbf43448380c09a6f5.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Suggested-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Remove printk from sampling loop

hwlat has some time operation checks on the sample loop, and it is
currently using pr_err (printk) to report them. The problem is that
this can lead the

trace/hwlat: Remove printk from sampling loop

hwlat has some time operation checks on the sample loop, and it is
currently using pr_err (printk) to report them. The problem is that
this can lead the system to an unresponsible state due to an overflow of
printk messages. This problem can be mitigated by writing the error
message to the trace buffer.

Remove the printk messages from the sampling loop, switching the to
messages in the trace buffer.

No functional change.

Link: https://lkml.kernel.org/r/9d77c34869748aa105e965c769d24642914eea3a.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Use trace_min_max_param for width and window params

Use the trace_min_max_param to reduce code duplication.

No functional change.

Link: https://lkml.kernel.org/r/b91accd5a7c6c14ea02d3

trace/hwlat: Use trace_min_max_param for width and window params

Use the trace_min_max_param to reduce code duplication.

No functional change.

Link: https://lkml.kernel.org/r/b91accd5a7c6c14ea02d3379aae974ba22b47dd6.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Implement the per-cpu mode

Implements the per-cpu mode in which a sampling thread is created for
each cpu in the "cpus" (and tracing_mask).

The per-cpu mode has the potention to speed

trace/hwlat: Implement the per-cpu mode

Implements the per-cpu mode in which a sampling thread is created for
each cpu in the "cpus" (and tracing_mask).

The per-cpu mode has the potention to speed up the hwlat detection by
running on multiple CPUs at the same time, at the cost of higher cpu
usage with irqs disabled. Use with care.

[
Changed get_cpu_data() to static.
Reported-by: kernel test robot <[email protected]>
]

Link: https://lkml.kernel.org/r/ec06d0ab340e8460d293772faba19ad8a5c371aa.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Switch disable_migrate to mode none

When in the round-robin mode, if the tracer detects a change in the
hwlatd thread affinity by an external tool, e.g., taskset, the
round-robin logic

trace/hwlat: Switch disable_migrate to mode none

When in the round-robin mode, if the tracer detects a change in the
hwlatd thread affinity by an external tool, e.g., taskset, the
round-robin logic is disabled. The disable_migrate variable currently
tracks this.

With the addition of the "mode" config and the mode "none," the
disable_migrate logic is equivalent to switch to the "none" mode.

Hence, instead of using a hidden variable to track this behavior,
switch the mode to none, informing the user about this change.

Link: https://lkml.kernel.org/r/a679af672458d6b1f62252605905c5214030f247.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Implement the mode config option

Provides the "mode" config to the hardware latency detector. hwlatd has
two different operation modes. The default mode is the "round-robin" one,
in whi

trace/hwlat: Implement the mode config option

Provides the "mode" config to the hardware latency detector. hwlatd has
two different operation modes. The default mode is the "round-robin" one,
in which a single hwlatd thread runs, migrating among the allowed CPUs in a
"round-robin" fashion. This is the current behavior.

The "none" sets the allowed cpumask for a single hwlatd thread at the
startup, but skips the round-robin, letting the scheduler handle the
migration.

In preparation to the per-cpu mode.

Link: https://lkml.kernel.org/r/f3b1271262aa030c680e26615c1b9b2d71e55e92.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

trace/hwlat: Fix Clark's email

Clark's email is [email protected].

No functional change.

Link: https://lkml.kernel.org/r/6fa4b49e17ab8a1ff19c335ab7cde38d8afb0e29.1624372313.git.bristot@redhat.co

trace/hwlat: Fix Clark's email

Clark's email is [email protected].

No functional change.

Link: https://lkml.kernel.org/r/6fa4b49e17ab8a1ff19c335ab7cde38d8afb0e29.1624372313.git.bristot@redhat.com

Cc: Phil Auld <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Kate Carcia <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Alexandre Chartre <[email protected]>
Cc: Clark Willaims <[email protected]>
Cc: John Kacur <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

tracing: Fix various typos in comments

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@g

tracing: Fix various typos in comments

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/[email protected]
Link: https://lkml.kernel.org/r/[email protected]

Reviewed-by: Randy Dunlap <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

tracing: Merge irqflags + preempt counter.

The state of the interrupts (irqflags) and the preemption counter are
both passed down to tracing_generic_entry_update(). Only one bit of
irqflags is actua

tracing: Merge irqflags + preempt counter.

The state of the interrupts (irqflags) and the preemption counter are
both passed down to tracing_generic_entry_update(). Only one bit of
irqflags is actually required: The on/off state. The complete 32bit
of the preemption counter isn't needed. Just whether of the upper bits
(softirq, hardirq and NMI) are set and the preemption depth is needed.

The irqflags and the preemption counter could be evaluated early and the
information stored in an integer `trace_ctx'.
tracing_generic_entry_update() would use the upper bits as the
TRACE_FLAG_* and the lower 8bit as the disabled-preemption depth
(considering that one must be substracted from the counter in one
special cases).

The actual preemption value is not used except for the tracing record.
The `irqflags' variable is mostly used only for the tracing record. An
exception here is for instance wakeup_tracer_call() or
probe_wakeup_sched_switch() which explicilty disable interrupts and use
that `irqflags' to save (and restore) the IRQ state and to record the
state.

Struct trace_event_buffer has also the `pc' and flags' members which can
be replaced with `trace_ctx' since their actual value is not used
outside of trace recording.

This will reduce tracing_generic_entry_update() to simply assign values
to struct trace_entry. The evaluation of the TRACE_FLAG_* bits is moved
to _tracing_gen_ctx_flags() which replaces preempt_count() and
local_save_flags() invocations.

As an example, ftrace_syscall_enter() may invoke:
- trace_buffer_lock_reserve() -> … -> tracing_generic_entry_update()
- event_trigger_unlock_commit()
-> ftrace_trace_stack() -> … -> tracing_generic_entry_update()
-> ftrace_trace_userstack() -> … -> tracing_generic_entry_update()

In this case the TRACE_FLAG_* bits were evaluated three times. By using
the `trace_ctx' they are evaluated once and assigned three times.

A build with all tracers enabled on x86-64 with and without the patch:

text data bss dec hex filename
21970669 17084168 7639260 46694097 2c87ed1 vmlinux.old
21970293 17084168 7639260 46693721 2c87d59 vmlinux.new

text shrank by 379 bytes, data remained constant.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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tracing: Remove WARN_ON in start_thread()

This patch reverts commit 978defee11a5 ("tracing: Do a WARN_ON()
if start_thread() in hwlat is called when thread exists")

.start hook can be legally call

tracing: Remove WARN_ON in start_thread()

This patch reverts commit 978defee11a5 ("tracing: Do a WARN_ON()
if start_thread() in hwlat is called when thread exists")

.start hook can be legally called several times if according
tracer is stopped

screen window 1
[root@localhost ~]# echo 1 > /sys/kernel/tracing/events/kmem/kfree/enable
[root@localhost ~]# echo 1 > /sys/kernel/tracing/options/pause-on-trace
[root@localhost ~]# less -F /sys/kernel/tracing/trace

screen window 2
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo hwlat > /sys/kernel/debug/tracing/current_tracer
[root@localhost ~]# echo 1 > /sys/kernel/debug/tracing/tracing_on
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo 2 > /sys/kernel/debug/tracing/tracing_on

triggers warning in dmesg:
WARNING: CPU: 3 PID: 1403 at kernel/trace/trace_hwlat.c:371 hwlat_tracer_start+0xc9/0xd0

Link: https://lkml.kernel.org/r/[email protected]

Cc: Ingo Molnar <[email protected]>
Cc: [email protected]
Fixes: 978defee11a5 ("tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists")
Signed-off-by: Vasily Averin <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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tracing: Fix some typos in comments

s/detetector/detector/
s/enfoced/enforced/
s/writen/written/
s/actualy/actually/
s/bascially/basically/
s/Regarldess/Regardless/
s/zeroes/zeros/
s/followd/followe

tracing: Fix some typos in comments

s/detetector/detector/
s/enfoced/enforced/
s/writen/written/
s/actualy/actually/
s/bascially/basically/
s/Regarldess/Regardless/
s/zeroes/zeros/
s/followd/followed/
s/incrememented/incremented/
s/separatelly/separately/
s/accesible/accessible/
s/sythetic/synthetic/
s/enabed/enabled/
s/heurisitc/heuristic/
s/assocated/associated/
s/otherwides/otherwise/
s/specfied/specified/
s/seaching/searching/
s/hierachry/hierarchy/
s/internel/internal/
s/Thise/This/

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Qiujun Huang <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer

Current tracing_init_dentry() return a d_entry pointer, while is not
necessary. This function returns NULL on succ

tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer

Current tracing_init_dentry() return a d_entry pointer, while is not
necessary. This function returns NULL on success or error on failure,
which means there is no valid d_entry pointer return.

Let's return 0 on success and negative value for error.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Wei Yang <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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tracing/hwlat: Honor the tracing_cpumask

In calculation of the cpu mask for the hwlat kernel thread, the wrong
cpu mask is used instead of the tracing_cpumask, this causes the
tracing/tracing_cpumas

tracing/hwlat: Honor the tracing_cpumask

In calculation of the cpu mask for the hwlat kernel thread, the wrong
cpu mask is used instead of the tracing_cpumask, this causes the
tracing/tracing_cpumask useless for hwlat tracer. Fixes it.

Link: https://lkml.kernel.org/r/[email protected]

Cc: Ingo Molnar <[email protected]>
Cc: [email protected]
Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Kevin Hao <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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