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![Waiman Long](/assets/img/avatar_default.png)
It was found that the use of up_read_non_owner() in NFS was causing
the following warning when DEBUG_RWSEMS was configured.
DEBUG_LOCKS_WARN_ON(sem->owner != ((struct task_struct *)(1UL << 0)))
Looking into the rwsem.c file, it was discovered that the corresponding
down_read_non_owner() function was not setting the owner field properly.
This is fixed now, and the warning should be gone.
Fixes: 5149cbac42
("locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Gavin Schenk <g.schenk@eckelmann.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-nfs@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1527168398-4291-1-git-send-email-longman@redhat.com
224 lines
4.4 KiB
C
224 lines
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* 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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int __sched down_read_killable(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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if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_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_reader_owned(sem);
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return 0;
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}
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EXPORT_SYMBOL(down_read_killable);
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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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DEBUG_RWSEMS_WARN_ON(sem->owner != RWSEM_READER_OWNED);
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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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DEBUG_RWSEMS_WARN_ON(sem->owner != current);
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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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DEBUG_RWSEMS_WARN_ON(sem->owner != current);
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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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rwsem_set_reader_owned(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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DEBUG_RWSEMS_WARN_ON(sem->owner != RWSEM_READER_OWNED);
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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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