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author | Nicholas Mc Guire <der.herr@hofr.at> | 2014-01-02 09:18:42 (GMT) |
---|---|---|
committer | Scott Wood <scottwood@freescale.com> | 2015-02-13 22:20:45 (GMT) |
commit | 937634f2854358d3cf38e95e2fd271cf0c24c7fe (patch) | |
tree | a904e05790b9c557c29b96d30b87a27051cb5a1b /kernel | |
parent | 805d5a3b8703a518c76fd7a6b14a46af251de054 (diff) | |
download | linux-fsl-qoriq-937634f2854358d3cf38e95e2fd271cf0c24c7fe.tar.xz |
write_lock migrate_disable pushdown to rt_write_lock
pushdown of migrate_disable/enable from write_*lock* to the rt_write_*lock*
api level
general mapping of write_*lock* to mutexes:
write_*lock*
`-> rt_write_*lock*
`-> __spin_lock (the sleeping __spin_lock)
`-> rt_mutex
write_*lock*s are non-recursive so we have two lock chains to consider
- write_trylock*/write_unlock
- write_lock*/wirte_unlock
for both paths the migration_disable/enable must be balanced.
write_trylock* mapping:
write_trylock_irqsave
`-> rt_write_trylock_irqsave
write_trylock \
`--------> rt_write_trylock
ret = rt_mutex_trylock
rt_mutex_fasttrylock
rt_mutex_cmpxchg
if (ret)
migrate_disable
write_lock* mapping:
write_lock_irqsave
`-> rt_write_lock_irqsave
write_lock_irq -> write_lock ----. \
write_lock_bh -+ \
`-> rt_write_lock
__rt_spin_lock()
rt_spin_lock_fastlock()
rt_mutex_cmpxchg()
migrate_disable()
write_unlock* mapping:
write_unlock_irqrestore.
write_unlock_bh -------+
write_unlock_irq -> write_unlock ----------+
`-> rt_write_unlock()
__rt_spin_unlock()
rt_spin_lock_fastunlock()
rt_mutex_cmpxchg()
migrate_enable()
So calls to migrate_disable/enable() are better placed at the rt_write_*
level of lock/trylock/unlock as all of the write_*lock* API has this as a
common path.
This approach to write_*_bh also eliminates the concerns raised with
regards to api inbalances (write_lock_bh -> write_unlock+local_bh_enable)
Tested-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/rt.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rt.c b/kernel/rt.c index d58b410..d712968 100644 --- a/kernel/rt.c +++ b/kernel/rt.c @@ -197,8 +197,6 @@ int __lockfunc rt_write_trylock_irqsave(rwlock_t *rwlock, unsigned long *flags) *flags = 0; ret = rt_write_trylock(rwlock); - if (ret) - migrate_disable(); return ret; } EXPORT_SYMBOL(rt_write_trylock_irqsave); @@ -232,6 +230,7 @@ EXPORT_SYMBOL(rt_read_trylock); void __lockfunc rt_write_lock(rwlock_t *rwlock) { rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_); + migrate_disable(); __rt_spin_lock(&rwlock->lock); } EXPORT_SYMBOL(rt_write_lock); @@ -257,6 +256,7 @@ void __lockfunc rt_write_unlock(rwlock_t *rwlock) /* NOTE: we always pass in '1' for nested, for simplicity */ rwlock_release(&rwlock->dep_map, 1, _RET_IP_); __rt_spin_unlock(&rwlock->lock); + migrate_enable(); } EXPORT_SYMBOL(rt_write_unlock); |