Messages in this thread Patch in this message |  | | From | Waiman Long <> | Subject | [PATCH v2 5/6] locking/lockdep: Decrement irq context counters when removing lock chain | Date | Mon, 16 Dec 2019 10:15:16 -0500 |
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There are currently three counters to track the irq context of a lock chain - nr_hardirq_chains, nr_softirq_chains and nr_process_chains. They are incremented when a new lock chain is added, but they are not decremented when a lock chain is removed. That causes some of the statistic counts reported by /proc/lockdep_stats to be incorrect.
Fix that by decrementing the right counter when a lock chain is removed.
Fixes: a0b0fd53e1e6 ("locking/lockdep: Free lock classes that are no longer in use") Signed-off-by: Waiman Long <longman@redhat.com> --- kernel/locking/lockdep.c | 35 +++++++++++++++++++++--------- kernel/locking/lockdep_internals.h | 6 +++++ 2 files changed, 31 insertions(+), 10 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index f7dcd4e77a70..4ea23bb6f8d3 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -2300,16 +2300,24 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, return 0; } -static void inc_chains(void) +static void inc_chains(int irq_context) { - if (current->hardirq_context) + if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) nr_hardirq_chains++; - else { - if (current->softirq_context) - nr_softirq_chains++; - else - nr_process_chains++; - } + else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) + nr_softirq_chains++; + else + nr_process_chains++; +} + +static void dec_chains(int irq_context) +{ + if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) + nr_hardirq_chains--; + else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) + nr_softirq_chains--; + else + nr_process_chains--; } #else @@ -2325,6 +2333,10 @@ static inline void inc_chains(void) nr_process_chains++; } +static void dec_chains(int irq_context) +{ + nr_process_chains--; +} #endif /* CONFIG_TRACE_IRQFLAGS */ static void @@ -3037,7 +3049,7 @@ static inline int add_chain_cache(struct task_struct *curr, chain_hlocks[chain->base + j] = class - lock_classes; hlist_add_head_rcu(&chain->entry, hash_head); debug_atomic_inc(chain_lookup_misses); - inc_chains(); + inc_chains(chain->irq_context); return 1; } @@ -3790,7 +3802,8 @@ mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) static inline unsigned int task_irq_context(struct task_struct *task) { - return 2 * !!task->hardirq_context + !!task->softirq_context; + return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context + + LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context; } static int separate_irq_context(struct task_struct *curr, @@ -4980,6 +4993,8 @@ static void remove_class_from_lock_chain(struct pending_free *pf, free_chain_hlocks(chain->base, chain->depth); /* Overwrite the chain key for concurrent RCU readers. */ WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY); + dec_chains(chain->irq_context); + /* * Note: calling hlist_del_rcu() from inside a * hlist_for_each_entry_rcu() loop is safe. diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index 91bbc5684103..9425155b9053 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -98,6 +98,12 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ = #define MAX_LOCKDEP_CHAINS_BITS 16 +/* + * Bit definitions for lock_chain.irq_context + */ +#define LOCK_CHAIN_SOFTIRQ_CONTEXT (1 << 0) +#define LOCK_CHAIN_HARDIRQ_CONTEXT (1 << 1) + /* * Stack-trace: tightly packed array of stack backtrace * addresses. Protected by the hash_lock. -- 2.18.1
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