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locking/rwlock: Provide RT variant

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Similar to rw_semaphores, on RT the rwlock substitution is not writer fair,
because it's not feasible to have a writer inherit its priority to
multiple readers. Readers blocked on a writer follow the normal rules of
priority inheritance. Like RT spinlocks, RT rwlocks are state preserving
across the slow lock operations (contended case).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211303.882793524@linutronix.de
This commit is contained in:
Thomas Gleixner
2021-08-15 23:28:28 +02:00
committed by Ingo Molnar
parent 0f383b6dc9
commit 8282947f67
7 changed files with 323 additions and 13 deletions
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5
kernel/locking/spinlock_debug.c
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@@ -31,6 +31,7 @@ void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
EXPORT_SYMBOL(__raw_spin_lock_init);
#ifndef CONFIG_PREEMPT_RT
void __rwlock_init(rwlock_t *lock, const char *name,
struct lock_class_key *key)
{
@@ -48,6 +49,7 @@ void __rwlock_init(rwlock_t *lock, const char *name,
}
EXPORT_SYMBOL(__rwlock_init);
#endif
static void spin_dump(raw_spinlock_t *lock, const char *msg)
{
@@ -139,6 +141,7 @@ void do_raw_spin_unlock(raw_spinlock_t *lock)
arch_spin_unlock(&lock->raw_lock);
}
#ifndef CONFIG_PREEMPT_RT
static void rwlock_bug(rwlock_t *lock, const char *msg)
{
if (!debug_locks_off())
@@ -228,3 +231,5 @@ void do_raw_write_unlock(rwlock_t *lock)
debug_write_unlock(lock);
arch_write_unlock(&lock->raw_lock);
}
#endif /* !CONFIG_PREEMPT_RT */