Commit 85b39d30 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Paul E. McKenney
Browse files

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: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent e02b2edf

include/linux/rcupdate.h

+1 −35
Original line number Diff line number Diff line
@@ -371,41 +371,7 @@ extern struct lockdep_map rcu_sched_lock_map; 
extern struct lockdep_map rcu_callback_map;

int debug_lockdep_rcu_enabled(void);



/**

 * 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.

 */

static inline 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);

}



/*

 * rcu_read_lock_bh_held() is defined out of line to avoid #include-file

 * hell.

 */

int rcu_read_lock_held(void);

int rcu_read_lock_bh_held(void);



/**

kernel/rcu/update.c

+32 −0
Original line number Diff line number Diff line
@@ -136,6 +136,38 @@ 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?

 *

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