diff options
| -rw-r--r-- | kernel/marker.c | 58 |
1 files changed, 52 insertions, 6 deletions
diff --git a/kernel/marker.c b/kernel/marker.c index fe5ca72f965..05a25776f71 100644 --- a/kernel/marker.c +++ b/kernel/marker.c @@ -60,6 +60,9 @@ struct marker_entry { struct marker_probe_closure single; struct marker_probe_closure *multi; int refcount; /* Number of times armed. 0 if disarmed. */ + struct rcu_head rcu; + void *oldptr; + unsigned char rcu_pending:1; unsigned char ptype:1; char name[0]; /* Contains name'\0'format'\0' */ }; @@ -196,6 +199,16 @@ void marker_probe_cb_noarg(const struct marker *mdata, void *call_private, ...) } EXPORT_SYMBOL_GPL(marker_probe_cb_noarg); +static void free_old_closure(struct rcu_head *head) +{ + struct marker_entry *entry = container_of(head, + struct marker_entry, rcu); + kfree(entry->oldptr); + /* Make sure we free the data before setting the pending flag to 0 */ + smp_wmb(); + entry->rcu_pending = 0; +} + static void debug_print_probes(struct marker_entry *entry) { int i; @@ -404,6 +417,7 @@ static struct marker_entry *add_marker(const char *name, const char *format) e->multi = NULL; e->ptype = 0; e->refcount = 0; + e->rcu_pending = 0; hlist_add_head(&e->hlist, head); return e; } @@ -433,6 +447,9 @@ static int remove_marker(const char *name) if (e->single.func != __mark_empty_function) return -EBUSY; hlist_del(&e->hlist); + /* Make sure the call_rcu has been executed */ + if (e->rcu_pending) + rcu_barrier_sched(); kfree(e); return 0; } @@ -462,8 +479,12 @@ static int marker_set_format(struct marker_entry **entry, const char *format) e->multi = (*entry)->multi; e->ptype = (*entry)->ptype; e->refcount = (*entry)->refcount; + e->rcu_pending = 0; hlist_add_before(&e->hlist, &(*entry)->hlist); hlist_del(&(*entry)->hlist); + /* Make sure the call_rcu has been executed */ + if ((*entry)->rcu_pending) + rcu_barrier_sched(); kfree(*entry); *entry = e; trace_mark(core_marker_format, "name %s format %s", @@ -637,6 +658,12 @@ int marker_probe_register(const char *name, const char *format, goto end; } } + /* + * If we detect that a call_rcu is pending for this marker, + * make sure it's executed now. + */ + if (entry->rcu_pending) + rcu_barrier_sched(); old = marker_entry_add_probe(entry, probe, probe_private); if (IS_ERR(old)) { ret = PTR_ERR(old); @@ -644,11 +671,16 @@ int marker_probe_register(const char *name, const char *format, } mutex_unlock(&markers_mutex); marker_update_probes(); /* may update entry */ - synchronize_sched(); - kfree(old); mutex_lock(&markers_mutex); entry = get_marker(name); WARN_ON(!entry); + if (entry->rcu_pending) + rcu_barrier_sched(); + entry->oldptr = old; + entry->rcu_pending = 1; + /* write rcu_pending before calling the RCU callback */ + smp_wmb(); + call_rcu_sched(&entry->rcu, free_old_closure); end: mutex_unlock(&markers_mutex); return ret; @@ -678,15 +710,22 @@ int marker_probe_unregister(const char *name, entry = get_marker(name); if (!entry) goto end; + if (entry->rcu_pending) + rcu_barrier_sched(); old = marker_entry_remove_probe(entry, probe, probe_private); mutex_unlock(&markers_mutex); marker_update_probes(); /* may update entry */ - synchronize_sched(); - kfree(old); mutex_lock(&markers_mutex); entry = get_marker(name); if (!entry) goto end; + if (entry->rcu_pending) + rcu_barrier_sched(); + entry->oldptr = old; + entry->rcu_pending = 1; + /* write rcu_pending before calling the RCU callback */ + smp_wmb(); + call_rcu_sched(&entry->rcu, free_old_closure); remove_marker(name); /* Ignore busy error message */ ret = 0; end: @@ -752,14 +791,21 @@ int marker_probe_unregister_private_data(marker_probe_func *probe, ret = -ENOENT; goto end; } + if (entry->rcu_pending) + rcu_barrier_sched(); old = marker_entry_remove_probe(entry, NULL, probe_private); mutex_unlock(&markers_mutex); marker_update_probes(); /* may update entry */ - synchronize_sched(); - kfree(old); mutex_lock(&markers_mutex); entry = get_marker_from_private_data(probe, probe_private); WARN_ON(!entry); + if (entry->rcu_pending) + rcu_barrier_sched(); + entry->oldptr = old; + entry->rcu_pending = 1; + /* write rcu_pending before calling the RCU callback */ + smp_wmb(); + call_rcu_sched(&entry->rcu, free_old_closure); remove_marker(entry->name); /* Ignore busy error message */ end: mutex_unlock(&markers_mutex); |