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![Waiman Long](/assets/img/avatar_default.png)
The current spinlock lockup detection code can sometimes produce false positives because of the unfairness of the locking algorithm itself. So the lockup detection code is now removed. Instead, we are relying on the NMI watchdog to detect potential lockup. We won't have lockup detection if the watchdog isn't running. The commented-out read-write lock lockup detection code are also removed. Signed-off-by: Waiman Long <longman@redhat.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: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1486583208-11038-1-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
226 lines
5.5 KiB
C
226 lines
5.5 KiB
C
/*
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* Copyright 2005, Red Hat, Inc., Ingo Molnar
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* Released under the General Public License (GPL).
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*
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* This file contains the spinlock/rwlock implementations for
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* DEBUG_SPINLOCK.
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*/
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#include <linux/spinlock.h>
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#include <linux/nmi.h>
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#include <linux/interrupt.h>
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#include <linux/debug_locks.h>
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#include <linux/delay.h>
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#include <linux/export.h>
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void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
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struct lock_class_key *key)
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{
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/*
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* Make sure we are not reinitializing a held lock:
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*/
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debug_check_no_locks_freed((void *)lock, sizeof(*lock));
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lockdep_init_map(&lock->dep_map, name, key, 0);
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#endif
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lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
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lock->magic = SPINLOCK_MAGIC;
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lock->owner = SPINLOCK_OWNER_INIT;
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lock->owner_cpu = -1;
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}
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EXPORT_SYMBOL(__raw_spin_lock_init);
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void __rwlock_init(rwlock_t *lock, const char *name,
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struct lock_class_key *key)
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{
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/*
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* Make sure we are not reinitializing a held lock:
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*/
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debug_check_no_locks_freed((void *)lock, sizeof(*lock));
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lockdep_init_map(&lock->dep_map, name, key, 0);
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#endif
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lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
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lock->magic = RWLOCK_MAGIC;
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lock->owner = SPINLOCK_OWNER_INIT;
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lock->owner_cpu = -1;
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}
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EXPORT_SYMBOL(__rwlock_init);
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static void spin_dump(raw_spinlock_t *lock, const char *msg)
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{
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struct task_struct *owner = NULL;
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if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
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owner = lock->owner;
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printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
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msg, raw_smp_processor_id(),
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current->comm, task_pid_nr(current));
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printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
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".owner_cpu: %d\n",
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lock, lock->magic,
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owner ? owner->comm : "<none>",
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owner ? task_pid_nr(owner) : -1,
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lock->owner_cpu);
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dump_stack();
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}
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static void spin_bug(raw_spinlock_t *lock, const char *msg)
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{
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if (!debug_locks_off())
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return;
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spin_dump(lock, msg);
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}
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#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
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static inline void
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debug_spin_lock_before(raw_spinlock_t *lock)
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{
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SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
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SPIN_BUG_ON(lock->owner == current, lock, "recursion");
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SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
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lock, "cpu recursion");
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}
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static inline void debug_spin_lock_after(raw_spinlock_t *lock)
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{
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lock->owner_cpu = raw_smp_processor_id();
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lock->owner = current;
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}
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static inline void debug_spin_unlock(raw_spinlock_t *lock)
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{
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SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
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SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
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SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
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SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
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lock, "wrong CPU");
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lock->owner = SPINLOCK_OWNER_INIT;
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lock->owner_cpu = -1;
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}
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/*
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* We are now relying on the NMI watchdog to detect lockup instead of doing
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* the detection here with an unfair lock which can cause problem of its own.
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*/
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void do_raw_spin_lock(raw_spinlock_t *lock)
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{
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debug_spin_lock_before(lock);
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arch_spin_lock(&lock->raw_lock);
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debug_spin_lock_after(lock);
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}
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int do_raw_spin_trylock(raw_spinlock_t *lock)
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{
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int ret = arch_spin_trylock(&lock->raw_lock);
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if (ret)
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debug_spin_lock_after(lock);
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#ifndef CONFIG_SMP
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/*
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* Must not happen on UP:
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*/
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SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
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#endif
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return ret;
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}
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void do_raw_spin_unlock(raw_spinlock_t *lock)
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{
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debug_spin_unlock(lock);
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arch_spin_unlock(&lock->raw_lock);
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}
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static void rwlock_bug(rwlock_t *lock, const char *msg)
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{
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if (!debug_locks_off())
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return;
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printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
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msg, raw_smp_processor_id(), current->comm,
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task_pid_nr(current), lock);
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dump_stack();
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}
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#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
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void do_raw_read_lock(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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arch_read_lock(&lock->raw_lock);
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}
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int do_raw_read_trylock(rwlock_t *lock)
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{
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int ret = arch_read_trylock(&lock->raw_lock);
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#ifndef CONFIG_SMP
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/*
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* Must not happen on UP:
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*/
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RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
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#endif
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return ret;
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}
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void do_raw_read_unlock(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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arch_read_unlock(&lock->raw_lock);
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}
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static inline void debug_write_lock_before(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
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RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
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lock, "cpu recursion");
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}
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static inline void debug_write_lock_after(rwlock_t *lock)
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{
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lock->owner_cpu = raw_smp_processor_id();
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lock->owner = current;
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}
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static inline void debug_write_unlock(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
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RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
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lock, "wrong CPU");
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lock->owner = SPINLOCK_OWNER_INIT;
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lock->owner_cpu = -1;
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}
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void do_raw_write_lock(rwlock_t *lock)
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{
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debug_write_lock_before(lock);
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arch_write_lock(&lock->raw_lock);
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debug_write_lock_after(lock);
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}
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int do_raw_write_trylock(rwlock_t *lock)
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{
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int ret = arch_write_trylock(&lock->raw_lock);
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if (ret)
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debug_write_lock_after(lock);
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#ifndef CONFIG_SMP
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/*
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* Must not happen on UP:
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*/
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RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
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#endif
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return ret;
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}
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void do_raw_write_unlock(rwlock_t *lock)
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{
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debug_write_unlock(lock);
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arch_write_unlock(&lock->raw_lock);
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}
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