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>

diff --git a/kernel/marker.c b/kernel/marker.c
index e9c6b2bc9400627cf183382ee55933333f0ee83b..75a1a17cd78a0765120214a21d23ad9e03d2768e 100644 (file)
--- 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;
        }