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ring-buffer: Remove duplicate use of '&' in recursive code

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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/alpine.DEB.2.11.1503271423580.23114@gentwo.org

Suggested-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2015-03-27 17:39:49 -04:00 committed by Steven Rostedt
parent d9a16d3ab8
commit d631c8cceb
1 changed files with 1 additions and 4 deletions
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5
kernel/trace/ring_buffer.c
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@ -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