c4be9cb4f1
Oleg Nesterov recently noticed that the lockdep annotations in lglock.c are not sufficient to detect some obvious deadlocks, such as lg_local_lock(LOCK) + lg_local_lock(LOCK) or spin_lock(X) + lg_local_lock(Y) vs lg_local_lock(Y) + spin_lock(X). Both issues are easily fixed by indicating to lockdep that lglock's local locks are not recursive. We shouldn't use the rwlock acquire/release functions here, as lglock doesn't share the same semantics. Instead we can base our lockdep annotations on the lock_acquire_shared (for local lglock) and lock_acquire_exclusive (for global lglock) helpers. I am not proposing new lglock specific helpers as I don't see the point of the existing second level of helpers :) Noticed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@linux.intel.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130708212352.1769031C15E@corp2gmr1-1.hot.corp.google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
/* See include/linux/lglock.h for description */
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#include <linux/module.h>
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#include <linux/lglock.h>
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#include <linux/cpu.h>
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#include <linux/string.h>
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/*
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* Note there is no uninit, so lglocks cannot be defined in
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* modules (but it's fine to use them from there)
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* Could be added though, just undo lg_lock_init
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*/
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void lg_lock_init(struct lglock *lg, char *name)
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{
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LOCKDEP_INIT_MAP(&lg->lock_dep_map, name, &lg->lock_key, 0);
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}
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EXPORT_SYMBOL(lg_lock_init);
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void lg_local_lock(struct lglock *lg)
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{
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arch_spinlock_t *lock;
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preempt_disable();
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lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
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lock = this_cpu_ptr(lg->lock);
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arch_spin_lock(lock);
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}
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EXPORT_SYMBOL(lg_local_lock);
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void lg_local_unlock(struct lglock *lg)
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{
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arch_spinlock_t *lock;
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lock_release(&lg->lock_dep_map, 1, _RET_IP_);
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lock = this_cpu_ptr(lg->lock);
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arch_spin_unlock(lock);
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preempt_enable();
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}
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EXPORT_SYMBOL(lg_local_unlock);
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void lg_local_lock_cpu(struct lglock *lg, int cpu)
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{
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arch_spinlock_t *lock;
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preempt_disable();
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lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
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lock = per_cpu_ptr(lg->lock, cpu);
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arch_spin_lock(lock);
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}
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EXPORT_SYMBOL(lg_local_lock_cpu);
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void lg_local_unlock_cpu(struct lglock *lg, int cpu)
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{
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arch_spinlock_t *lock;
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lock_release(&lg->lock_dep_map, 1, _RET_IP_);
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lock = per_cpu_ptr(lg->lock, cpu);
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arch_spin_unlock(lock);
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preempt_enable();
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}
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EXPORT_SYMBOL(lg_local_unlock_cpu);
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void lg_global_lock(struct lglock *lg)
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{
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int i;
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preempt_disable();
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lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
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for_each_possible_cpu(i) {
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arch_spinlock_t *lock;
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lock = per_cpu_ptr(lg->lock, i);
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arch_spin_lock(lock);
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}
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}
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EXPORT_SYMBOL(lg_global_lock);
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void lg_global_unlock(struct lglock *lg)
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{
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int i;
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lock_release(&lg->lock_dep_map, 1, _RET_IP_);
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for_each_possible_cpu(i) {
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arch_spinlock_t *lock;
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lock = per_cpu_ptr(lg->lock, i);
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arch_spin_unlock(lock);
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}
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preempt_enable();
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}
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EXPORT_SYMBOL(lg_global_unlock);
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