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srcu: Shrink Tiny SRCU a bit

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In Tiny SRCU, __srcu_read_lock() is a trivial function, outweighed by
its EXPORT_SYMBOL_GPL(), and on many architectures, its call sequence.
This commit therefore moves it to srcutiny.h so that it can be inlined.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2017-04-28 14:16:16 -07:00
parent 07f6e64bf2
commit d4efe6c5ad
2 changed files with 15 additions and 16 deletions
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15
include/linux/srcutiny.h
View file

@ -63,6 +63,21 @@ void srcu_drive_gp(struct work_struct *wp);
void synchronize_srcu(struct srcu_struct *sp);
/*
* Counts the new reader in the appropriate per-CPU element of the
* srcu_struct. Can be invoked from irq/bh handlers, but the matching
* __srcu_read_unlock() must be in the same handler instance. Returns an
* index that must be passed to the matching srcu_read_unlock().
*/
static inline int __srcu_read_lock(struct srcu_struct *sp)
{
int idx;
idx = READ_ONCE(sp->srcu_idx);
WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1);
return idx;
}
static inline void synchronize_srcu_expedited(struct srcu_struct *sp)
{
synchronize_srcu(sp);

16
kernel/rcu/srcutiny.c
View file

@ -95,22 +95,6 @@ void cleanup_srcu_struct(struct srcu_struct *sp)
}
EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
/*
* Counts the new reader in the appropriate per-CPU element of the
* srcu_struct. Can be invoked from irq/bh handlers, but the matching
* __srcu_read_unlock() must be in the same handler instance. Returns an
* index that must be passed to the matching srcu_read_unlock().
*/
int __srcu_read_lock(struct srcu_struct *sp)
{
int idx;
idx = READ_ONCE(sp->srcu_idx);
WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1);
return idx;
}
EXPORT_SYMBOL_GPL(__srcu_read_lock);
/*
* Removes the count for the old reader from the appropriate element of
* the srcu_struct.