perf: Fix perf ring buffer memory ordering

The PPC64 people noticed a missing memory barrier and crufty old
comments in the perf ring buffer code. So update all the comments and
add the missing barrier.

When the architecture implements local_t using atomic_long_t there
will be double barriers issued; but short of introducing more
conditional barrier primitives this is the best we can do.

Reported-by: Victor Kaplansky <[email protected]>
Tested-by: Victor Kaplansky <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: [email protected]
Cc: Paul McKenney <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions