rcu: Fix dyntick-idle tracing

Browse source

The tracing subsystem started using rcu_irq_entry() and rcu_irq_exit()
(with my blessing) to allow the current _rcuidle alternative tracepoint
name to be dispensed with while still maintaining good performance.
Unfortunately, this causes RCU's dyntick-idle entry code's tracing to
appear to RCU like an interrupt that occurs where RCU is not designed
to handle interrupts.

This commit fixes this problem by moving the zeroing of ->dynticks_nesting
after the offending trace_rcu_dyntick() statement, which narrows the
window of vulnerability to a pair of adjacent statements that are now
marked with comments to that effect.

Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.home
Link: http://lkml.kernel.org/r/20170405193928.GM1600@linux.vnet.ibm.com

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

...

This commit is contained in:

Paul E. McKenney 2017-04-05 09:05:18 -07:00 • committed by Steven Rostedt (VMware)

parent 8aaf1ee70e

commit a278d47189

1 changed files with 23 additions and 25 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

48

kernel/rcu/tree.c

View file