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![J. R. Okajima](/assets/img/avatar_default.png)
Commit:
f8319483f5
("locking/lockdep: Provide a type check for lock_is_held")
didn't fully cover rwsems as downgrade_write() was left out.
Introduce lock_downgrade() and use it to add new checks.
See-also: http://marc.info/?l=linux-kernel&m=148581164003149&w=2
Originally-written-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1486053497-9948-3-git-send-email-hooanon05g@gmail.com
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
204 lines
3.8 KiB
C
204 lines
3.8 KiB
C
/* kernel/rwsem.c: R/W semaphores, public implementation
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*
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* Written by David Howells (dhowells@redhat.com).
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* Derived from asm-i386/semaphore.h
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/export.h>
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#include <linux/rwsem.h>
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#include <linux/atomic.h>
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#include "rwsem.h"
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/*
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* lock for reading
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*/
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void __sched down_read(struct rw_semaphore *sem)
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{
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might_sleep();
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rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
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LOCK_CONTENDED(sem, __down_read_trylock, __down_read);
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rwsem_set_reader_owned(sem);
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}
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EXPORT_SYMBOL(down_read);
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/*
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* trylock for reading -- returns 1 if successful, 0 if contention
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*/
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int down_read_trylock(struct rw_semaphore *sem)
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{
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int ret = __down_read_trylock(sem);
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if (ret == 1) {
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rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
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rwsem_set_reader_owned(sem);
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}
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return ret;
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}
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EXPORT_SYMBOL(down_read_trylock);
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/*
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* lock for writing
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*/
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void __sched down_write(struct rw_semaphore *sem)
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{
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might_sleep();
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rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
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LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
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rwsem_set_owner(sem);
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}
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EXPORT_SYMBOL(down_write);
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/*
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* lock for writing
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*/
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int __sched down_write_killable(struct rw_semaphore *sem)
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{
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might_sleep();
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rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
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if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock, __down_write_killable)) {
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rwsem_release(&sem->dep_map, 1, _RET_IP_);
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return -EINTR;
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}
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rwsem_set_owner(sem);
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return 0;
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}
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EXPORT_SYMBOL(down_write_killable);
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/*
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* trylock for writing -- returns 1 if successful, 0 if contention
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*/
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int down_write_trylock(struct rw_semaphore *sem)
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{
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int ret = __down_write_trylock(sem);
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if (ret == 1) {
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rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_);
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rwsem_set_owner(sem);
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}
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return ret;
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}
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EXPORT_SYMBOL(down_write_trylock);
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/*
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* release a read lock
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*/
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void up_read(struct rw_semaphore *sem)
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{
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rwsem_release(&sem->dep_map, 1, _RET_IP_);
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__up_read(sem);
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}
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EXPORT_SYMBOL(up_read);
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/*
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* release a write lock
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*/
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void up_write(struct rw_semaphore *sem)
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{
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rwsem_release(&sem->dep_map, 1, _RET_IP_);
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rwsem_clear_owner(sem);
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__up_write(sem);
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}
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EXPORT_SYMBOL(up_write);
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/*
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* downgrade write lock to read lock
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*/
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void downgrade_write(struct rw_semaphore *sem)
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{
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lock_downgrade(&sem->dep_map, _RET_IP_);
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rwsem_set_reader_owned(sem);
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__downgrade_write(sem);
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}
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EXPORT_SYMBOL(downgrade_write);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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void down_read_nested(struct rw_semaphore *sem, int subclass)
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{
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might_sleep();
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rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_);
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LOCK_CONTENDED(sem, __down_read_trylock, __down_read);
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rwsem_set_reader_owned(sem);
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}
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EXPORT_SYMBOL(down_read_nested);
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void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)
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{
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might_sleep();
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rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_);
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LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
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rwsem_set_owner(sem);
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}
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EXPORT_SYMBOL(_down_write_nest_lock);
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void down_read_non_owner(struct rw_semaphore *sem)
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{
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might_sleep();
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__down_read(sem);
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}
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EXPORT_SYMBOL(down_read_non_owner);
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void down_write_nested(struct rw_semaphore *sem, int subclass)
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{
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might_sleep();
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rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_);
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LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
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rwsem_set_owner(sem);
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}
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EXPORT_SYMBOL(down_write_nested);
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int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass)
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{
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might_sleep();
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rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_);
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if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock, __down_write_killable)) {
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rwsem_release(&sem->dep_map, 1, _RET_IP_);
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return -EINTR;
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}
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rwsem_set_owner(sem);
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return 0;
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}
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EXPORT_SYMBOL(down_write_killable_nested);
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void up_read_non_owner(struct rw_semaphore *sem)
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{
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__up_read(sem);
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}
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EXPORT_SYMBOL(up_read_non_owner);
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#endif
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