1 files changed, 24 insertions, 12 deletions

diff --git a/kernel/marker.c b/kernel/marker.c
index 7d1faecd7a51..e9c6b2bc9400 100644
--- a/kernel/marker.c
+++ b/kernel/marker.c
@@ -62,7 +62,7 @@ struct marker_entry {
         int refcount;   /* Number of times armed. 0 if disarmed. */
         struct rcu_head rcu;
         void *oldptr;
-        unsigned char rcu_pending:1;
+        int rcu_pending;
         unsigned char ptype:1;
         char name[0];   /* Contains name'\0'format'\0' */
 };
@@ -103,11 +103,11 @@ 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 +145,7 @@ 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 +162,7 @@ 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;
@@ -195,7 +195,7 @@ 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);
 
@@ -560,7 +560,7 @@ 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)
 {
@@ -653,11 +653,17 @@ int marker_probe_register(const char *name, const char *format,
         entry = get_marker(name);
         if (!entry) {
                 entry = add_marker(name, format);
-                if (IS_ERR(entry)) {
+                if (IS_ERR(entry))
                         ret = PTR_ERR(entry);
-                        goto end;
-                }
+        } else if (format) {
+                if (!entry->format)
+                        ret = marker_set_format(&entry, format);
+                else if (strcmp(entry->format, format))
+                        ret = -EPERM;
         }
+        if (ret)
+                goto end;
+
         /*
          * If we detect that a call_rcu is pending for this marker,
          * make sure it's executed now.
@@ -674,6 +680,8 @@ int marker_probe_register(const char *name, const char *format,
         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 */
@@ -717,6 +725,8 @@ int marker_probe_unregister(const char *name,
         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 */
@@ -795,6 +805,8 @@ int marker_probe_unregister_private_data(marker_probe_func *probe,
         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 */