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264d4f88ad
The synchronize_rcu() definition based on RW-locks in whatisRCU.txt
does not meet the "Memory-Barrier Guarantees" in Requirements.html;
for example, the following SB-like test:
P0: P1:
WRITE_ONCE(x, 1); WRITE_ONCE(y, 1);
synchronize_rcu(); smp_mb();
r0 = READ_ONCE(y); r1 = READ_ONCE(x);
should not be allowed to reach the state "r0 = 0 AND r1 = 0", but
the current write_lock()+write_unlock() definition can not ensure
this. This commit therefore inserts an smp_mb__after_spinlock()
in order to cause this synchronize_rcu() implementation to provide
this memory-barrier guarantee.
Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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|---|---|---|
| .. | ||
| Design | ||
| 00-INDEX | ||
| arrayRCU.txt | ||
| checklist.txt | ||
| listRCU.txt | ||
| lockdep-splat.txt | ||
| lockdep.txt | ||
| NMI-RCU.txt | ||
| rcu_dereference.txt | ||
| rcu.txt | ||
| rcubarrier.txt | ||
| rculist_nulls.txt | ||
| rcuref.txt | ||
| RTFP.txt | ||
| stallwarn.txt | ||
| torture.txt | ||
| UP.txt | ||
| whatisRCU.txt | ||