diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2011-10-05 11:59:38 -0700 |
|---|---|---|
| committer | Clark Williams <williams@redhat.com> | 2011-12-28 16:25:45 -0600 |
| commit | 73cfea2a2670b6fe3863c674281df7be99420101 (patch) | |
| tree | 4301f2102d3f134a33877f5a3a5c56362b6dfda2 /kernel/rcupdate.c | |
| parent | bcaa134d0cad10094b3758960ae08edd34d7a75e (diff) | |
rcu: Merge RCU-bh into RCU-preempt
The Linux kernel has long RCU-bh read-side critical sections that
intolerably increase scheduling latency under mainline's RCU-bh rules,
which include RCU-bh read-side critical sections being non-preemptible.
This patch therefore arranges for RCU-bh to be implemented in terms of
RCU-preempt for CONFIG_PREEMPT_RT_FULL=y.
This has the downside of defeating the purpose of RCU-bh, namely,
handling the case where the system is subjected to a network-based
denial-of-service attack that keeps at least one CPU doing full-time
softirq processing. This issue will be fixed by a later commit.
The current commit will need some work to make it appropriate for
mainline use, for example, it needs to be extended to cover Tiny RCU.
[ paulmck: Added a useful changelog ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20111005185938.GA20403@linux.vnet.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/rcupdate.c')
| -rw-r--r-- | kernel/rcupdate.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index c5b98e565aee..24dcc713bd00 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -77,6 +77,7 @@ int debug_lockdep_rcu_enabled(void) } EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); +#ifndef CONFIG_PREEMPT_RT_FULL /** * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? * @@ -96,6 +97,7 @@ int rcu_read_lock_bh_held(void) return in_softirq() || irqs_disabled(); } EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); +#endif #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |