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author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-05-21 11:58:36 -0700 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-07-02 12:34:23 -0700 |
commit | 2a3fa843b555d202e682bf08c65ee1a4a93c79cf (patch) | |
tree | b7db689ab83f041319b80493b12a8f7ecc79ad0f /kernel/rcupdate.c | |
parent | e9023c4061054cbf59c5288068118a4d0b152f01 (diff) | |
download | kernel_goldelico_gta04-2a3fa843b555d202e682bf08c65ee1a4a93c79cf.zip kernel_goldelico_gta04-2a3fa843b555d202e682bf08c65ee1a4a93c79cf.tar.gz kernel_goldelico_gta04-2a3fa843b555d202e682bf08c65ee1a4a93c79cf.tar.bz2 |
rcu: Consolidate tree/tiny __rcu_read_{,un}lock() implementations
The CONFIG_TREE_PREEMPT_RCU and CONFIG_TINY_PREEMPT_RCU versions of
__rcu_read_lock() and __rcu_read_unlock() are identical, so this commit
consolidates them into kernel/rcupdate.h.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcupdate.c')
-rw-r--r-- | kernel/rcupdate.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 95cba41..4e6a61b 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -54,6 +54,50 @@ #ifdef CONFIG_PREEMPT_RCU /* + * Preemptible RCU implementation for rcu_read_lock(). + * Just increment ->rcu_read_lock_nesting, shared state will be updated + * if we block. + */ +void __rcu_read_lock(void) +{ + current->rcu_read_lock_nesting++; + barrier(); /* critical section after entry code. */ +} +EXPORT_SYMBOL_GPL(__rcu_read_lock); + +/* + * Preemptible RCU implementation for rcu_read_unlock(). + * Decrement ->rcu_read_lock_nesting. If the result is zero (outermost + * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then + * invoke rcu_read_unlock_special() to clean up after a context switch + * in an RCU read-side critical section and other special cases. + */ +void __rcu_read_unlock(void) +{ + struct task_struct *t = current; + + if (t->rcu_read_lock_nesting != 1) { + --t->rcu_read_lock_nesting; + } else { + barrier(); /* critical section before exit code. */ + t->rcu_read_lock_nesting = INT_MIN; + barrier(); /* assign before ->rcu_read_unlock_special load */ + if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special))) + rcu_read_unlock_special(t); + barrier(); /* ->rcu_read_unlock_special load before assign */ + t->rcu_read_lock_nesting = 0; + } +#ifdef CONFIG_PROVE_LOCKING + { + int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting); + + WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2); + } +#endif /* #ifdef CONFIG_PROVE_LOCKING */ +} +EXPORT_SYMBOL_GPL(__rcu_read_unlock); + +/* * Check for a task exiting while in a preemptible-RCU read-side * critical section, clean up if so. No need to issue warnings, * as debug_check_no_locks_held() already does this if lockdep |