提交 e3818b8d 编写于 作者: P Paul E. McKenney 提交者: Ingo Molnar

rcu: Make rcu_read_lock_bh_held() allow for disabled BH

Disabling BH can stand in for rcu_read_lock_bh(), and this patch
updates rcu_read_lock_bh_held() to allow for this.  In order to
avoid include-file hell, this function is moved out of line to
kernel/rcupdate.c.

This fixes a false positive RCU warning.
Reported-by: NArnd Bergmann <arnd@arndb.de>
Reported-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <20100316000343.GA25857@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
上级 a3d3203e
......@@ -123,22 +123,11 @@ static inline int rcu_read_lock_held(void)
return lock_is_held(&rcu_lock_map);
}
/**
* rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
*
* If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
* an RCU-bh read-side critical section. In absence of CONFIG_PROVE_LOCKING,
* this assumes we are in an RCU-bh read-side critical section unless it can
* prove otherwise.
*
* Check rcu_scheduler_active to prevent false positives during boot.
/*
* rcu_read_lock_bh_held() is defined out of line to avoid #include-file
* hell.
*/
static inline int rcu_read_lock_bh_held(void)
{
if (!debug_lockdep_rcu_enabled())
return 1;
return lock_is_held(&rcu_bh_lock_map);
}
extern int rcu_read_lock_bh_held(void);
/**
* rcu_read_lock_sched_held - might we be in RCU-sched read-side critical section?
......
......@@ -45,6 +45,7 @@
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/kernel_stat.h>
#include <linux/hardirq.h>
#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key rcu_lock_key;
......@@ -66,6 +67,28 @@ EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
int rcu_scheduler_active __read_mostly;
EXPORT_SYMBOL_GPL(rcu_scheduler_active);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/**
* 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
* CONFIG_PROVE_RCU and not cases. Note that if someone uses
* rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
* will show the situation.
*
* Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
*/
int rcu_read_lock_bh_held(void)
{
if (!debug_lockdep_rcu_enabled())
return 1;
return in_softirq();
}
EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
/*
* This function is invoked towards the end of the scheduler's initialization
* process. Before this is called, the idle task might contain
......
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