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SubjectRe: [PATCH 05/05] update - Linux Kernel Markers, non optimised architectures
* Nick Piggin (nickpiggin@yahoo.com.au) wrote:
> OK, well one problem is that it can cause a resched event to be lost, so
> you might say it has more side-effects without checking resched.
>

Here is the patch that implements this. I also did a cosmetic change to
linux/marker.h. Preliminary tests of running the markers with preempt_enable()
with LTTng 0.6.56 instrumentation shows no problem.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

--- a/include/asm-generic/marker.h
+++ b/include/asm-generic/marker.h
@@ -39,7 +39,7 @@ struct __mark_marker {
if (unlikely(__marker_enable_##name)) { \
preempt_disable(); \
(*__mark_call_##name)(format, ## args); \
- preempt_enable_no_resched(); \
+ preempt_enable(); \
} \
} while (0)

--- a/include/asm-i386/marker.h
+++ b/include/asm-i386/marker.h
@@ -42,7 +42,7 @@ struct __mark_marker {
if (unlikely(condition)) { \
preempt_disable(); \
(*__mark_call_##name)(format, ## args); \
- preempt_enable_no_resched(); \
+ preempt_enable(); \
} \
} while (0)

--- a/include/asm-powerpc/marker.h
+++ b/include/asm-powerpc/marker.h
@@ -45,7 +45,7 @@ struct __mark_marker {
if (unlikely(condition)) { \
preempt_disable(); \
(*__mark_call_##name)(format, ## args); \
- preempt_enable_no_resched(); \
+ preempt_enable(); \
} \
} while (0)

--- a/include/linux/marker.h
+++ b/include/linux/marker.h
@@ -8,12 +8,12 @@
*
* Example :
*
- * MARK(subsystem_event, "%d %s %p[struct task_struct *]",
+ * MARK(subsystem_event, "%d %s %p[struct task_struct]",
* someint, somestring, current);
* Where :
* - Subsystem is the name of your subsystem.
* - event is the name of the event to mark.
- * - "%d %s %p[struct task_struct *]" is the formatted string for printk.
+ * - "%d %s %p[struct task_struct]" is the formatted string for printk.
* - someint is an integer.
* - somestring is a char pointer.
* - current is a pointer to a struct task_struct.
@@ -27,6 +27,9 @@
* Markers can be put in inline functions, inlined static functions and
* unrolled loops.
*
+ * Note : It is safe to put markers within preempt-safe code : preempt_enable()
+ * will not call the scheduler due to the tests in preempt_schedule().
+ *
* (C) Copyright 2006 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
*
* This file is released under the GPLv2.
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