markers: simplify marker_set_format()

current marker_set_format() is complex this patch simplify it,
and decrease the overhead of marker_update_probes().

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 25 insertions, 46 deletions

diff --git a/kernel/marker.c b/kernel/marker.c
index e9c6b2bc9400..75a1a17cd78a 100644
--- a/kernel/marker.c
+++ b/kernel/marker.c
@@ -64,6 +64,7 @@ struct marker_entry {
         void *oldptr;
         int rcu_pending;
         unsigned char ptype:1;
+        unsigned char format_allocated:1;
         char name[0];   /* Contains name'\0'format'\0' */
 };
 
@@ -416,6 +417,7 @@ static struct marker_entry *add_marker(const char *name, const char *format)
         e->single.probe_private = NULL;
         e->multi = NULL;
         e->ptype = 0;
+        e->format_allocated = 0;
         e->refcount = 0;
         e->rcu_pending = 0;
         hlist_add_head(&e->hlist, head);
@@ -447,6 +449,8 @@ static int remove_marker(const char *name)
         if (e->single.func != __mark_empty_function)
                 return -EBUSY;
         hlist_del(&e->hlist);
+        if (e->format_allocated)
+                kfree(e->format);
         /* Make sure the call_rcu has been executed */
         if (e->rcu_pending)
                 rcu_barrier_sched();
@@ -457,57 +461,34 @@ static int remove_marker(const char *name)
 /*
  * Set the mark_entry format to the format found in the element.
  */
-static int marker_set_format(struct marker_entry **entry, const char *format)
+static int marker_set_format(struct marker_entry *entry, const char *format)
 {
-        struct marker_entry *e;
-        size_t name_len = strlen((*entry)->name) + 1;
-        size_t format_len = strlen(format) + 1;
-
-
-        e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
-                        GFP_KERNEL);
-        if (!e)
+        entry->format = kstrdup(format, GFP_KERNEL);
+        if (!entry->format)
                 return -ENOMEM;
-        memcpy(&e->name[0], (*entry)->name, name_len);
-        e->format = &e->name[name_len];
-        memcpy(e->format, format, format_len);
-        if (strcmp(e->format, MARK_NOARGS) == 0)
-                e->call = marker_probe_cb_noarg;
-        else
-                e->call = marker_probe_cb;
-        e->single = (*entry)->single;
-        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;
+        entry->format_allocated = 1;
+
         trace_mark(core_marker_format, "name %s format %s",
-                        e->name, e->format);
+                        entry->name, entry->format);
         return 0;
 }
 
 /*
  * Sets the probe callback corresponding to one marker.
  */
-static int set_marker(struct marker_entry **entry, struct marker *elem,
+static int set_marker(struct marker_entry *entry, struct marker *elem,
                 int active)
 {
         int ret;
-        WARN_ON(strcmp((*entry)->name, elem->name) != 0);
+        WARN_ON(strcmp(entry->name, elem->name) != 0);
 
-        if ((*entry)->format) {
-                if (strcmp((*entry)->format, elem->format) != 0) {
+        if (entry->format) {
+                if (strcmp(entry->format, elem->format) != 0) {
                         printk(KERN_NOTICE
                                 "Format mismatch for probe %s "
                                 "(%s), marker (%s)\n",
-                                (*entry)->name,
-                                (*entry)->format,
+                                entry->name,
+                                entry->format,
                                 elem->format);
                         return -EPERM;
                 }
@@ -523,34 +504,33 @@ static int set_marker(struct marker_entry **entry, struct marker *elem,
          * pass from a "safe" callback (with argument) to an "unsafe"
          * callback (does not set arguments).
          */
-        elem->call = (*entry)->call;
+        elem->call = entry->call;
         /*
          * Sanity check :
          * We only update the single probe private data when the ptr is
          * set to a _non_ single probe! (0 -> 1 and N -> 1, N != 1)
          */
         WARN_ON(elem->single.func != __mark_empty_function
-                && elem->single.probe_private
-                != (*entry)->single.probe_private &&
-                !elem->ptype);
-        elem->single.probe_private = (*entry)->single.probe_private;
+                && elem->single.probe_private != entry->single.probe_private
+                && !elem->ptype);
+        elem->single.probe_private = entry->single.probe_private;
         /*
          * Make sure the private data is valid when we update the
          * single probe ptr.
          */
         smp_wmb();
-        elem->single.func = (*entry)->single.func;
+        elem->single.func = entry->single.func;
         /*
          * We also make sure that the new probe callbacks array is consistent
          * before setting a pointer to it.
          */
-        rcu_assign_pointer(elem->multi, (*entry)->multi);
+        rcu_assign_pointer(elem->multi, entry->multi);
         /*
          * Update the function or multi probe array pointer before setting the
          * ptype.
          */
         smp_wmb();
-        elem->ptype = (*entry)->ptype;
+        elem->ptype = entry->ptype;
         elem->state = active;
 
         return 0;
@@ -594,8 +574,7 @@ void marker_update_probe_range(struct marker *begin,
         for (iter = begin; iter < end; iter++) {
                 mark_entry = get_marker(iter->name);
                 if (mark_entry) {
-                        set_marker(&mark_entry, iter,
-                                        !!mark_entry->refcount);
+                        set_marker(mark_entry, iter, !!mark_entry->refcount);
                         /*
                          * ignore error, continue
                          */
@@ -657,7 +636,7 @@ int marker_probe_register(const char *name, const char *format,
                         ret = PTR_ERR(entry);
         } else if (format) {
                 if (!entry->format)
-                        ret = marker_set_format(&entry, format);
+                        ret = marker_set_format(entry, format);
                 else if (strcmp(entry->format, format))
                         ret = -EPERM;
         }