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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2012-11-29 16:46:05 +0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-02-07 15:10:39 -0800 |
| commit | 3bc97a782cc8c112f64a25143452b06206364cc8 (patch) | |
| tree | b09b1d1be6158948d9bb0f848dcd3d66f3b17737 /include/linux | |
| parent | ab4d2986e44c589aa1b647d7da5e21c2707babea (diff) | |
| download | linux-stable-3bc97a782cc8c112f64a25143452b06206364cc8.tar.gz linux-stable-3bc97a782cc8c112f64a25143452b06206364cc8.tar.bz2 linux-stable-3bc97a782cc8c112f64a25143452b06206364cc8.zip | |
srcu: Remove checks preventing offline CPUs from calling srcu_read_lock()
SRCU has its own statemachine and no longer relies on normal RCU.
Its read-side critical section can now be used by an offline CPU, so this
commit removes the check and the comments, reverting the SRCU portion
of c0d6d01b (rcu: Check for illegal use of RCU from offlined CPUs).
It also makes the code match the comments in whatisRCU.txt:
g. Do you need read-side critical sections that are respected
even though they are in the middle of the idle loop, during
user-mode execution, or on an offlined CPU? If so, SRCU is the
only choice that will work for you.
[ paulmck: There is at least one remaining issue, namely use of lockdep
with tracing enabled. ]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/srcu.h | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 6eb691b08358..ae3ee39eb699 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -163,9 +163,6 @@ void srcu_barrier(struct srcu_struct *sp); * power mode. This way we can notice an extended quiescent state to * other CPUs that started a grace period. Otherwise we would delay any * grace period as long as we run in the idle task. - * - * Similarly, we avoid claiming an SRCU read lock held if the current - * CPU is offline. */ static inline int srcu_read_lock_held(struct srcu_struct *sp) { @@ -173,8 +170,6 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp) return 1; if (rcu_is_cpu_idle()) return 0; - if (!rcu_lockdep_current_cpu_online()) - return 0; return lock_is_held(&sp->dep_map); } |