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| author | Li Zhong <zhong@linux.vnet.ibm.com> | 2012-09-19 08:52:32 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-09-23 07:42:52 -0700 |
| commit | 22a767269a767b3ee91e4aaea353ac6bec6a912d (patch) | |
| tree | 21ed83a572e345a81a9ed17182e0cf393712b003 /kernel/rcutiny.c | |
| parent | 58fac09566bb48592a09ef0fe0c7dbefa0cd2109 (diff) | |
| download | linux-22a767269a767b3ee91e4aaea353ac6bec6a912d.tar.bz2 | |
rcu: Move TINY_RCU quiescent state out of extended quiescent state
TINY_RCU's rcu_idle_enter_common() invokes rcu_sched_qs() in order
to inform the RCU core of the quiescent state implied by idle entry.
Of course, idle is also an extended quiescent state, so that the call
to rcu_sched_qs() speeds up RCU's invoking of any callbacks that might
be queued. This speed-up is important when entering into dyntick-idle
mode -- if there are no further scheduling-clock interrupts, the callbacks
might never be invoked, which could result in a system hang.
However, processing callbacks does event tracing, which in turn
implies RCU read-side critical sections, which are illegal in extended
quiescent states. This patch therefore moves the call to rcu_sched_qs()
so that it precedes the point at which we inform lockdep that RCU has
entered an extended quiescent state.
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutiny.c')
| -rw-r--r-- | kernel/rcutiny.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 2e073a24d250..e4c6a598d6f7 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -75,9 +75,9 @@ static void rcu_idle_enter_common(long long newval) current->pid, current->comm, idle->pid, idle->comm); /* must be idle task! */ } + rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ barrier(); rcu_dynticks_nesting = newval; - rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ } /* |