markers: fix unregister bug and reenter bug, cleanup

[linux-2.6-block.git] / kernel / marker.c

diff --git a/kernel/marker.c b/kernel/marker.c
index 7d1faecd7a51bd643cc1e10f0f2048765136bf16..fe5ca72f96597e57d8fdd2c7c5e7566f59b73b71 100644 (file)
--- a/kernel/marker.c
+++ b/kernel/marker.c
@@ -60,9 +60,6 @@ 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' */
 };
@@ -103,11 +100,11 @@ void marker_probe_cb(const struct marker *mdata, void *call_private, ...)
        char ptype;
 
        /*
-        * preempt_disable does two things : disabling preemption to make sure
-        * the teardown of the callbacks can be done correctly when they are in
-        * modules and they insure RCU read coherency.
+        * rcu_read_lock_sched does two things : disabling preemption to make
+        * sure the teardown of the callbacks can be done correctly when they
+        * are in modules and they insure RCU read coherency.
         */
-       preempt_disable();
+       rcu_read_lock_sched();
        ptype = mdata->ptype;
        if (likely(!ptype)) {
                marker_probe_func *func;
@@ -145,7 +142,7 @@ void marker_probe_cb(const struct marker *mdata, void *call_private, ...)
                        va_end(args);
                }
        }
-       preempt_enable();
+       rcu_read_unlock_sched();
 }
 EXPORT_SYMBOL_GPL(marker_probe_cb);
 
@@ -162,7 +159,7 @@ void marker_probe_cb_noarg(const struct marker *mdata, void *call_private, ...)
        va_list args;   /* not initialized */
        char ptype;
 
-       preempt_disable();
+       rcu_read_lock_sched();
        ptype = mdata->ptype;
        if (likely(!ptype)) {
                marker_probe_func *func;
@@ -195,20 +192,10 @@ void marker_probe_cb_noarg(const struct marker *mdata, void *call_private, ...)
                        multi[i].func(multi[i].probe_private, call_private,
                                mdata->format, &args);
        }
-       preempt_enable();
+       rcu_read_unlock_sched();
 }
 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;
@@ -417,7 +404,6 @@ 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;
 }
@@ -447,9 +433,6 @@ 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;
 }
@@ -479,12 +462,8 @@ 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",
@@ -560,7 +539,7 @@ static int set_marker(struct marker_entry **entry, struct marker *elem,
  * Disable a marker and its probe callback.
  * Note: only waiting an RCU period after setting elem->call to the empty
  * function insures that the original callback is not used anymore. This insured
- * by preempt_disable around the call site.
+ * by rcu_read_lock_sched around the call site.
  */
 static void disable_marker(struct marker *elem)
 {
@@ -658,12 +637,6 @@ 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);
@@ -671,14 +644,11 @@ 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);
-       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;
@@ -708,20 +678,15 @@ 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;
-       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:
@@ -787,19 +752,14 @@ 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);
-       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);