git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
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Head SHA1: d631c8cceb1d1d06f372878935949d421585186b
Steven Rostedt (Red Hat) (1):
ring-buffer: Remove duplicate use of '&' in recursive code
----
kernel/trace/ring_buffer.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
---------------------------
commit d631c8cceb1d1d06f372878935949d421585186b
Author: Steven Rostedt (Red Hat) <[email protected]>
Date: Fri Mar 27 17:39:49 2015 -0400
ring-buffer: Remove duplicate use of '&' in recursive code
A clean up of the recursive protection code changed
val = this_cpu_read(current_context);
val--;
val &= this_cpu_read(current_context);
to
val = this_cpu_read(current_context);
val &= val & (val - 1);
Which has a duplicate use of '&' as the above is the same as
val = val & (val - 1);
Actually, it would be best to remove that line altogether and
just add it to where it is used.
And Christoph even mentioned that it can be further compacted to
just a single line:
__this_cpu_and(current_context, __this_cpu_read(current_context) - 1);
Link: http://lkml.kernel.org/[email protected]
Suggested-by: Christoph Lameter <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 922048a0f7ea..0315d43176d8 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2703,10 +2703,7 @@ static __always_inline int trace_recursive_lock(void)
static __always_inline void trace_recursive_unlock(void)
{
- unsigned int val = __this_cpu_read(current_context);
-
- val &= val & (val - 1);
- __this_cpu_write(current_context, val);
+ __this_cpu_and(current_context, __this_cpu_read(current_context) - 1);
}
#else
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