diff options
author | 2014-07-08 15:17:59 -0700 | |
---|---|---|
committer | 2014-09-07 16:18:13 -0700 | |
commit | 85b39d305bfe809a11ff2770d380be3e2465beec (patch) | |
tree | 2bc6f52c07779203329b0d791f631ab894a8846e /kernel/rcu/update.c | |
parent | rcu: Use true/false instead of 1/0 for a bool type (diff) | |
download | linux-85b39d305bfe809a11ff2770d380be3e2465beec.tar.gz linux-85b39d305bfe809a11ff2770d380be3e2465beec.tar.bz2 linux-85b39d305bfe809a11ff2770d380be3e2465beec.zip |
rcu: Uninline rcu_read_lock_held()
This commit uninlines rcu_read_lock_held(). According to "size vmlinux"
this saves 28549 in .text:
- 5541731 3014560 14757888 23314179
+ 5513182 3026848 14757888 23297918
Note: it looks as if the data grows by 12288 bytes but this is not true,
it does not actually grow. But .data starts with ALIGN(THREAD_SIZE) and
since .text shrinks the padding grows, and thus .data grows too as it
seen by /bin/size. diff System.map:
- ffffffff81510000 D _sdata
- ffffffff81510000 D init_thread_union
+ ffffffff81509000 D _sdata
+ ffffffff8150c000 D init_thread_union
Perhaps we can change vmlinux.lds.S to .data itself, so that /bin/size
can't "wrongly" report that .data grows if .text shinks.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/update.c')
-rw-r--r-- | kernel/rcu/update.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 4056d7992a6c..ea8ea7b16e11 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -137,6 +137,38 @@ int notrace debug_lockdep_rcu_enabled(void) EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); /** + * rcu_read_lock_held() - might we be in RCU read-side critical section? + * + * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU + * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, + * this assumes we are in an RCU read-side critical section unless it can + * prove otherwise. This is useful for debug checks in functions that + * require that they be called within an RCU read-side critical section. + * + * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot + * and while lockdep is disabled. + * + * Note that rcu_read_lock() and the matching rcu_read_unlock() must + * occur in the same context, for example, it is illegal to invoke + * rcu_read_unlock() in process context if the matching rcu_read_lock() + * was invoked from within an irq handler. + * + * Note that rcu_read_lock() is disallowed if the CPU is either idle or + * offline from an RCU perspective, so check for those as well. + */ +int rcu_read_lock_held(void) +{ + if (!debug_lockdep_rcu_enabled()) + return 1; + if (!rcu_is_watching()) + return 0; + if (!rcu_lockdep_current_cpu_online()) + return 0; + return lock_is_held(&rcu_lock_map); +} +EXPORT_SYMBOL_GPL(rcu_read_lock_held); + +/** * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? * * Check for bottom half being disabled, which covers both the |