linux-toradex.git/include/trace/ftrace.h, branch v3.12.51 Linux kernel for Apalis and Colibri modules tracing: Fix array size mismatch in format string 2014-03-31T12:22:25+00:00 Vaibhav Nagarnaik vnagarnaik@google.com 2014-02-14T03:51:48+00:00 c0316f975b1a29a1161f86d524150f493188e9b2 commit 87291347c49dc40aa339f587b209618201c2e527 upstream. In event format strings, the array size is reported in two locations. One in array subscript and then via the "size:" attribute. The values reported there have a mismatch. For e.g., in sched:sched_switch the prev_comm and next_comm character arrays have subscript values as [32] where as the actual field size is 16. name: sched_switch ID: 301 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1;signed:0; field:int common_pid; offset:4; size:4; signed:1; field:char prev_comm[32]; offset:8; size:16; signed:1; field:pid_t prev_pid; offset:24; size:4; signed:1; field:int prev_prio; offset:28; size:4; signed:1; field:long prev_state; offset:32; size:8; signed:1; field:char next_comm[32]; offset:40; size:16; signed:1; field:pid_t next_pid; offset:56; size:4; signed:1; field:int next_prio; offset:60; size:4; signed:1; After bisection, the following commit was blamed: 92edca0 tracing: Use direct field, type and system names This commit removes the duplication of strings for field->name and field->type assuming that all the strings passed in __trace_define_field() are immutable. This is not true for arrays, where the type string is created in event_storage variable and field->type for all array fields points to event_storage. Use __stringify() to create a string constant for the type string. Also, get rid of event_storage and event_storage_mutex that are not needed anymore. also, an added benefit is that this reduces the overhead of events a bit more: text data bss dec hex filename 8424787 2036472 1302528 11763787 b3804b vmlinux 8420814 2036408 1302528 11759750 b37086 vmlinux.patched Link: http://lkml.kernel.org/r/1392349908-29685-1-git-send-email-vnagarnaik@google.com Cc: Laurent Chavey <chavey@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 87291347c49dc40aa339f587b209618201c2e527 upstream.

In event format strings, the array size is reported in two locations.
One in array subscript and then via the "size:" attribute. The values
reported there have a mismatch.

For e.g., in sched:sched_switch the prev_comm and next_comm character
arrays have subscript values as [32] where as the actual field size is
16.

name: sched_switch
ID: 301
format:
        field:unsigned short common_type;       offset:0;       size:2; signed:0;
        field:unsigned char common_flags;       offset:2;       size:1; signed:0;
        field:unsigned char common_preempt_count;       offset:3;       size:1;signed:0;
        field:int common_pid;   offset:4;       size:4; signed:1;

        field:char prev_comm[32];       offset:8;       size:16;        signed:1;
        field:pid_t prev_pid;   offset:24;      size:4; signed:1;
        field:int prev_prio;    offset:28;      size:4; signed:1;
        field:long prev_state;  offset:32;      size:8; signed:1;
        field:char next_comm[32];       offset:40;      size:16;        signed:1;
        field:pid_t next_pid;   offset:56;      size:4; signed:1;
        field:int next_prio;    offset:60;      size:4; signed:1;

After bisection, the following commit was blamed:
92edca0 tracing: Use direct field, type and system names

This commit removes the duplication of strings for field->name and
field->type assuming that all the strings passed in
__trace_define_field() are immutable. This is not true for arrays, where
the type string is created in event_storage variable and field->type for
all array fields points to event_storage.

Use __stringify() to create a string constant for the type string.

Also, get rid of event_storage and event_storage_mutex that are not
needed anymore.

also, an added benefit is that this reduces the overhead of events a bit more:

   text    data     bss     dec     hex filename
8424787 2036472 1302528 11763787         b3804b vmlinux
8420814 2036408 1302528 11759750         b37086 vmlinux.patched

Link: http://lkml.kernel.org/r/1392349908-29685-1-git-send-email-vnagarnaik@google.com

Cc: Laurent Chavey <chavey@google.com>
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
tracing: Allow events to have NULL strings 2013-12-04T19:05:56+00:00 Steven Rostedt (Red Hat) rostedt@goodmis.org 2013-11-26T14:22:54+00:00 845058c554ca1265158b88933131ae2e73cdb554 commit 4e58e54754dc1fec21c3a9e824bc108b05fdf46e upstream. If an TRACE_EVENT() uses __assign_str() or __get_str on a NULL pointer then the following oops will happen: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<c127a17b>] strlen+0x10/0x1a *pde = 00000000 ^M Oops: 0000 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.13.0-rc1-test+ #2 Hardware name: /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006^M task: f5cde9f0 ti: f5e5e000 task.ti: f5e5e000 EIP: 0060:[<c127a17b>] EFLAGS: 00210046 CPU: 1 EIP is at strlen+0x10/0x1a EAX: 00000000 EBX: c2472da8 ECX: ffffffff EDX: c2472da8 ESI: c1c5e5fc EDI: 00000000 EBP: f5e5fe84 ESP: f5e5fe80 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 CR0: 8005003b CR2: 00000000 CR3: 01f32000 CR4: 000007d0 Stack: f5f18b90 f5e5feb8 c10687a8 0759004f 00000005 00000005 00000005 00200046 00000002 00000000 c1082a93 f56c7e28 c2472da8 c1082a93 f5e5fee4 c106bc61^M 00000000 c1082a93 00000000 00000000 00000001 00200046 00200082 00000000 Call Trace: [<c10687a8>] ftrace_raw_event_lock+0x39/0xc0 [<c1082a93>] ? ktime_get+0x29/0x69 [<c1082a93>] ? ktime_get+0x29/0x69 [<c106bc61>] lock_release+0x57/0x1a5 [<c1082a93>] ? ktime_get+0x29/0x69 [<c10824dd>] read_seqcount_begin.constprop.7+0x4d/0x75 [<c1082a93>] ? ktime_get+0x29/0x69^M [<c1082a93>] ktime_get+0x29/0x69 [<c108a46a>] __tick_nohz_idle_enter+0x1e/0x426 [<c10690e8>] ? lock_release_holdtime.part.19+0x48/0x4d [<c10bc184>] ? time_hardirqs_off+0xe/0x28 [<c1068c82>] ? trace_hardirqs_off_caller+0x3f/0xaf [<c108a8cb>] tick_nohz_idle_enter+0x59/0x62 [<c1079242>] cpu_startup_entry+0x64/0x192 [<c102299c>] start_secondary+0x277/0x27c Code: 90 89 c6 89 d0 88 c4 ac 38 e0 74 09 84 c0 75 f7 be 01 00 00 00 89 f0 48 5e 5d c3 55 89 e5 57 66 66 66 66 90 83 c9 ff 89 c7 31 c0 <f2> ae f7 d1 8d 41 ff 5f 5d c3 55 89 e5 57 66 66 66 66 90 31 ff EIP: [<c127a17b>] strlen+0x10/0x1a SS:ESP 0068:f5e5fe80 CR2: 0000000000000000 ---[ end trace 01bc47bf519ec1b2 ]--- New tracepoints have been added that have allowed for NULL pointers being assigned to strings. To fix this, change the TRACE_EVENT() code to check for NULL and if it is, it will assign "(null)" to it instead (similar to what glibc printf does). Reported-by: Shuah Khan <shuah.kh@samsung.com> Reported-by: Jovi Zhangwei <jovi.zhangwei@gmail.com> Link: http://lkml.kernel.org/r/CAGdX0WFeEuy+DtpsJzyzn0343qEEjLX97+o1VREFkUEhndC+5Q@mail.gmail.com Link: http://lkml.kernel.org/r/528D6972.9010702@samsung.com Fixes: 9cbf117662e2 ("tracing/events: provide string with undefined size support") Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4e58e54754dc1fec21c3a9e824bc108b05fdf46e upstream.

If an TRACE_EVENT() uses __assign_str() or __get_str on a NULL pointer
then the following oops will happen:

BUG: unable to handle kernel NULL pointer dereference at   (null)
IP: [<c127a17b>] strlen+0x10/0x1a
*pde = 00000000 ^M
Oops: 0000 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.13.0-rc1-test+ #2
Hardware name:                  /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006^M
task: f5cde9f0 ti: f5e5e000 task.ti: f5e5e000
EIP: 0060:[<c127a17b>] EFLAGS: 00210046 CPU: 1
EIP is at strlen+0x10/0x1a
EAX: 00000000 EBX: c2472da8 ECX: ffffffff EDX: c2472da8
ESI: c1c5e5fc EDI: 00000000 EBP: f5e5fe84 ESP: f5e5fe80
 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
CR0: 8005003b CR2: 00000000 CR3: 01f32000 CR4: 000007d0
Stack:
 f5f18b90 f5e5feb8 c10687a8 0759004f 00000005 00000005 00000005 00200046
 00000002 00000000 c1082a93 f56c7e28 c2472da8 c1082a93 f5e5fee4 c106bc61^M
 00000000 c1082a93 00000000 00000000 00000001 00200046 00200082 00000000
Call Trace:
 [<c10687a8>] ftrace_raw_event_lock+0x39/0xc0
 [<c1082a93>] ? ktime_get+0x29/0x69
 [<c1082a93>] ? ktime_get+0x29/0x69
 [<c106bc61>] lock_release+0x57/0x1a5
 [<c1082a93>] ? ktime_get+0x29/0x69
 [<c10824dd>] read_seqcount_begin.constprop.7+0x4d/0x75
 [<c1082a93>] ? ktime_get+0x29/0x69^M
 [<c1082a93>] ktime_get+0x29/0x69
 [<c108a46a>] __tick_nohz_idle_enter+0x1e/0x426
 [<c10690e8>] ? lock_release_holdtime.part.19+0x48/0x4d
 [<c10bc184>] ? time_hardirqs_off+0xe/0x28
 [<c1068c82>] ? trace_hardirqs_off_caller+0x3f/0xaf
 [<c108a8cb>] tick_nohz_idle_enter+0x59/0x62
 [<c1079242>] cpu_startup_entry+0x64/0x192
 [<c102299c>] start_secondary+0x277/0x27c
Code: 90 89 c6 89 d0 88 c4 ac 38 e0 74 09 84 c0 75 f7 be 01 00 00 00 89 f0 48 5e 5d c3 55 89 e5 57 66 66 66 66 90 83 c9 ff 89 c7 31 c0 <f2> ae f7 d1 8d 41 ff 5f 5d c3 55 89 e5 57 66 66 66 66 90 31 ff
EIP: [<c127a17b>] strlen+0x10/0x1a SS:ESP 0068:f5e5fe80
CR2: 0000000000000000
---[ end trace 01bc47bf519ec1b2 ]---

New tracepoints have been added that have allowed for NULL pointers
being assigned to strings. To fix this, change the TRACE_EVENT() code
to check for NULL and if it is, it will assign "(null)" to it instead
(similar to what glibc printf does).

Reported-by: Shuah Khan <shuah.kh@samsung.com>
Reported-by: Jovi Zhangwei <jovi.zhangwei@gmail.com>
Link: http://lkml.kernel.org/r/CAGdX0WFeEuy+DtpsJzyzn0343qEEjLX97+o1VREFkUEhndC+5Q@mail.gmail.com
Link: http://lkml.kernel.org/r/528D6972.9010702@samsung.com
Fixes: 9cbf117662e2 ("tracing/events: provide string with undefined size support")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible 2013-08-14T01:06:30+00:00 Oleg Nesterov oleg@redhat.com 2013-08-06T16:08:47+00:00 d027e6a9c83440bf1ca9e5503539d58d8e0914f1 perf_trace_buf_prepare() + perf_trace_buf_submit(task => NULL) make no sense if hlist_empty(head). Change perf_trace_##call() to check ->perf_events beforehand and do nothing if it is empty. This removes the overhead for tasks without events associated with them. For example, "perf record -e sched:sched_switch -p1" attaches the counter(s) to the single task, but every task in system will do perf_trace_buf_prepare/submit() just to realize that it was not attached to this event. However, we can only do this if __task == NULL, so we also add the __builtin_constant_p(__task) check. With this patch "perf bench sched pipe" shows approximately 4% improvement when "perf record -p1" runs in parallel, many thanks to Steven for the testing. Link: http://lkml.kernel.org/r/20130806160847.GA2746@redhat.com Tested-by: David Ahern <dsahern@gmail.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> 
perf_trace_buf_prepare() + perf_trace_buf_submit(task => NULL)
make no sense if hlist_empty(head). Change perf_trace_##call()
to check ->perf_events beforehand and do nothing if it is empty.

This removes the overhead for tasks without events associated
with them. For example, "perf record -e sched:sched_switch -p1"
attaches the counter(s) to the single task, but every task in
system will do perf_trace_buf_prepare/submit() just to realize
that it was not attached to this event.

However, we can only do this if __task == NULL, so we also add
the __builtin_constant_p(__task) check.

With this patch "perf bench sched pipe" shows approximately 4%
improvement when "perf record -p1" runs in parallel, many thanks
to Steven for the testing.

Link: http://lkml.kernel.org/r/20130806160847.GA2746@redhat.com

Tested-by: David Ahern <dsahern@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing/perf: Reimplement TP_perf_assign() logic 2013-08-14T01:05:57+00:00 Oleg Nesterov oleg@redhat.com 2013-08-06T16:08:44+00:00 12473965c38a527a0c6f7a38d23edce60957f873 The next patch tries to avoid the costly perf_trace_buf_* calls when possible but there is a problem. We can only do this if __task == NULL, perf_tp_event(task != NULL) has the additional code for this case. Unfortunately, TP_perf_assign/__perf_xxx which changes the default values of __count/__task variables for perf_trace_buf_submit() is called "too late", after we already did perf_trace_buf_prepare(), and the optimization above can't work. So this patch simply embeds __perf_xxx() into TP_ARGS(), this way DECLARE_EVENT_CLASS() can use the result of assignments hidden in "args" right after ftrace_get_offsets_##call() which is mostly trivial. This allows us to have the fast-path "__task != NULL" check at the start, see the next patch. Link: http://lkml.kernel.org/r/20130806160844.GA2739@redhat.com Tested-by: David Ahern <dsahern@gmail.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> 
The next patch tries to avoid the costly perf_trace_buf_* calls
when possible but there is a problem. We can only do this if
__task == NULL, perf_tp_event(task != NULL) has the additional
code for this case.

Unfortunately, TP_perf_assign/__perf_xxx which changes the default
values of __count/__task variables for perf_trace_buf_submit() is
called "too late", after we already did perf_trace_buf_prepare(),
and the optimization above can't work.

So this patch simply embeds __perf_xxx() into TP_ARGS(), this way
DECLARE_EVENT_CLASS() can use the result of assignments hidden in
"args" right after ftrace_get_offsets_##call() which is mostly
trivial. This allows us to have the fast-path "__task != NULL"
check at the start, see the next patch.

Link: http://lkml.kernel.org/r/20130806160844.GA2739@redhat.com

Tested-by: David Ahern <dsahern@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing/perf: Expand TRACE_EVENT(sched_stat_runtime) 2013-08-14T01:05:12+00:00 Oleg Nesterov oleg@redhat.com 2013-08-06T16:08:41+00:00 36009d07b79d2a168d6037947357d96e5d8cebe7 To simplify the review of the next patches: 1. We are going to reimplent __perf_task/counter and embedd them into TP_ARGS(). expand TRACE_EVENT(sched_stat_runtime) into DECLARE_EVENT_CLASS() + DEFINE_EVENT(), this way they can use different TP_ARGS's. 2. Change perf_trace_##call() macro to do perf_fetch_caller_regs() right before perf_trace_buf_prepare(). This way it evaluates TP_ARGS() asap, the next patch explores this fact. Note: after 87f44bbc perf_trace_buf_prepare() doesn't need "struct pt_regs *regs", perhaps it makes sense to remove this argument. And perhaps we can teach perf_trace_buf_submit() to accept regs == NULL and do fetch_caller_regs(CALLER_ADDR1) in this case. 3. Cosmetic, but the typecast from "void*" buys nothing. It just adds the noise, remove it. Link: http://lkml.kernel.org/r/20130806160841.GA2736@redhat.com Acked-by: Peter Zijlstra <peterz@infradead.org> Tested-by: David Ahern <dsahern@gmail.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> 
To simplify the review of the next patches:

1. We are going to reimplent __perf_task/counter and embedd them
   into TP_ARGS(). expand TRACE_EVENT(sched_stat_runtime) into
   DECLARE_EVENT_CLASS() + DEFINE_EVENT(), this way they can use
   different TP_ARGS's.

2. Change perf_trace_##call() macro to do perf_fetch_caller_regs()
   right before perf_trace_buf_prepare().

   This way it evaluates TP_ARGS() asap, the next patch explores
   this fact.

   Note: after 87f44bbc perf_trace_buf_prepare() doesn't need
   "struct pt_regs *regs", perhaps it makes sense to remove this
   argument. And perhaps we can teach perf_trace_buf_submit()
   to accept regs == NULL and do fetch_caller_regs(CALLER_ADDR1)
   in this case.

3. Cosmetic, but the typecast from "void*" buys nothing. It just
   adds the noise, remove it.

Link: http://lkml.kernel.org/r/20130806160841.GA2736@redhat.com

Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare() 2013-07-19T01:31:28+00:00 Oleg Nesterov oleg@redhat.com 2013-06-17T17:02:11+00:00 cd92bf61d6d70bd3eb33b46d600e3f3eb9c5778a Every perf_trace_buf_prepare() caller does WARN_ONCE(size > PERF_MAX_TRACE_SIZE, message) and "message" is almost the same. Shift this WARN_ONCE() into perf_trace_buf_prepare(). This changes the meaning of _ONCE, but I think this is fine. - 4947014 2932448 10104832 17984294 1126b26 vmlinux + 4948422 2932448 10104832 17985702 11270a6 vmlinux on my build. Link: http://lkml.kernel.org/r/20130617170211.GA19813@redhat.com Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> 
Every perf_trace_buf_prepare() caller does
WARN_ONCE(size > PERF_MAX_TRACE_SIZE, message) and "message" is
almost the same.

Shift this WARN_ONCE() into perf_trace_buf_prepare(). This changes
the meaning of _ONCE, but I think this is fine.

	- 4947014 2932448 10104832  17984294  1126b26 vmlinux
	+ 4948422 2932448 10104832  17985702  11270a6 vmlinux

on my build.

Link: http://lkml.kernel.org/r/20130617170211.GA19813@redhat.com

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Add DEFINE_EVENT_FN() macro 2013-06-21T05:24:32+00:00 Steven Rostedt rostedt@goodmis.org 2013-06-20T15:44:44+00:00 f5abaa1bfc3dbf26d19d3513f39279ca369f8d65 Each TRACE_EVENT() adds several helper functions. If two or more trace events share the same structure and print format, they can also share most of these helper functions and save a lot of space from duplicate code. This is why the DECLARE_EVENT_CLASS() and DEFINE_EVENT() were created. Some events require a trigger to be called at registering and unregistering of the event and to do so they use TRACE_EVENT_FN(). If multiple events require a trigger, they currently have no choice but to use TRACE_EVENT_FN() as there's no DEFINE_EVENT_FN() available. This unfortunately causes a lot of wasted duplicate code created. By adding a DEFINE_EVENT_FN(), these events can still use a DECLARE_EVENT_CLASS() and then define their own triggers. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/51C3236C.8030508@hds.com Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
Each TRACE_EVENT() adds several helper functions. If two or more trace events
share the same structure and print format, they can also share most of these
helper functions and save a lot of space from duplicate code. This is why the
DECLARE_EVENT_CLASS() and DEFINE_EVENT() were created.

Some events require a trigger to be called at registering and unregistering of
the event and to do so they use TRACE_EVENT_FN().

If multiple events require a trigger, they currently have no choice but to use
TRACE_EVENT_FN() as there's no DEFINE_EVENT_FN() available. This unfortunately
causes a lot of wasted duplicate code created.

By adding a DEFINE_EVENT_FN(), these events can still use a
DECLARE_EVENT_CLASS() and then define their own triggers.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/51C3236C.8030508@hds.com
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
tracing: Remove obsolete macro guard _TRACE_PROFILE_INIT 2013-04-13T03:02:33+00:00 zhangwei(Jovi) jovi.zhangwei@huawei.com 2013-03-18T03:07:26+00:00 c192c8356cc878cfa98ebd3056478674786c0a4d The macro _TRACE_PROFILE_INIT was removed a long time ago, but an "#undef" guard was left behind. Remove it. Link: http://lkml.kernel.org/r/514684EE.6000805@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> 
The macro _TRACE_PROFILE_INIT was removed a long time ago,
but an "#undef" guard was left behind. Remove it.

Link: http://lkml.kernel.org/r/514684EE.6000805@huawei.com

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Add a way to soft disable trace events 2013-03-15T04:36:03+00:00 Steven Rostedt (Red Hat) rostedt@goodmis.org 2013-03-12T17:26:18+00:00 417944c4c7a0f657158d0515f3b8e8c043fd788f In order to let triggers enable or disable events, we need a 'soft' method for doing so. For example, if a function probe is added that lets a user enable or disable events when a function is called, that change must be done without taking locks or a mutex, and definitely it can't sleep. But the full enabling of a tracepoint is expensive. By adding a 'SOFT_DISABLE' flag, and converting the flags to be updated without the protection of a mutex (using set/clear_bit()), this soft disable flag can be used to allow critical sections to enable or disable events from being traced (after the event has been placed into "SOFT_MODE"). Some caveats though: The comm recorder (to map pids with a comm) can not be soft disabled (yet). If you disable an event with with a "soft" disable and wait a while before reading the trace, the comm cache may be replaced and you'll get a bunch of <...> for comms in the trace. Reading the "enable" file for an event that is disabled will now give you "0*" where the '*' denotes that the tracepoint is still active but the event itself is "disabled". [ fixed _BIT used in & operation : thanks to Dan Carpenter and smatch ] Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> 
In order to let triggers enable or disable events, we need a 'soft'
method for doing so. For example, if a function probe is added that
lets a user enable or disable events when a function is called, that
change must be done without taking locks or a mutex, and definitely
it can't sleep. But the full enabling of a tracepoint is expensive.

By adding a 'SOFT_DISABLE' flag, and converting the flags to be updated
without the protection of a mutex (using set/clear_bit()), this soft
disable flag can be used to allow critical sections to enable or disable
events from being traced (after the event has been placed into "SOFT_MODE").

Some caveats though: The comm recorder (to map pids with a comm) can not
be soft disabled (yet). If you disable an event with with a "soft"
disable and wait a while before reading the trace, the comm cache may be
replaced and you'll get a bunch of <...> for comms in the trace.

Reading the "enable" file for an event that is disabled will now give
you "0*" where the '*' denotes that the tracepoint is still active but
the event itself is "disabled".

[ fixed _BIT used in & operation : thanks to Dan Carpenter and smatch ]

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Fix some section mismatch warnings 2013-03-15T04:34:54+00:00 Li Zefan lizefan@huawei.com 2013-03-04T06:15:59+00:00 523c81135bb23b2d9a8c21365d90d21b1309c138 As we've added __init annotation to field-defining functions, we should add __refdata annotation to event_call variables, which reference those functions. Link: http://lkml.kernel.org/r/51343C1F.2050502@huawei.com Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> 
As we've added __init annotation to field-defining functions, we should
add __refdata annotation to event_call variables, which reference those
functions.

Link: http://lkml.kernel.org/r/51343C1F.2050502@huawei.com

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>