2 files changed, 148 insertions, 18 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 6658a51390fe..ab1c46e70bb6 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -37,6 +37,7 @@ struct ftrace_ops {
 #ifdef CONFIG_DYNAMIC_FTRACE
         struct ftrace_hash              *notrace_hash;
         struct ftrace_hash              *filter_hash;
+        unsigned long                   flags;
 #endif
 };
 
@@ -152,10 +153,13 @@ extern void unregister_ftrace_function_probe_all(char *glob);
 extern int ftrace_text_reserved(void *start, void *end);
 
 enum {
-        FTRACE_FL_FREE          = (1 << 0),
-        FTRACE_FL_ENABLED       = (1 << 1),
+        FTRACE_FL_ENABLED       = (1 << 30),
+        FTRACE_FL_FREE          = (1 << 31),
 };
 
+#define FTRACE_FL_MASK          (0x3UL << 30)
+#define FTRACE_REF_MAX          ((1 << 30) - 1)
+
 struct dyn_ftrace {
         union {
                 unsigned long           ip; /* address of mcount call-site */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 46f08264980b..5dd332cc5aa8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -890,6 +890,10 @@ static const struct ftrace_hash empty_hash = {
 };
 #define EMPTY_HASH      ((struct ftrace_hash *)&empty_hash)
 
+enum {
+        FTRACE_OPS_FL_ENABLED           = 1,
+};
+
 struct ftrace_ops global_ops = {
         .func                   = ftrace_stub,
         .notrace_hash           = EMPTY_HASH,
@@ -1161,6 +1165,105 @@ ftrace_hash_move(struct ftrace_hash **dst, struct ftrace_hash *src)
                 }                               \
         }
 
+static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
+                                     int filter_hash,
+                                     bool inc)
+{
+        struct ftrace_hash *hash;
+        struct ftrace_hash *other_hash;
+        struct ftrace_page *pg;
+        struct dyn_ftrace *rec;
+        int count = 0;
+        int all = 0;
+
+        /* Only update if the ops has been registered */
+        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
+                return;
+
+        /*
+         * In the filter_hash case:
+         *   If the count is zero, we update all records.
+         *   Otherwise we just update the items in the hash.
+         *
+         * In the notrace_hash case:
+         *   We enable the update in the hash.
+         *   As disabling notrace means enabling the tracing,
+         *   and enabling notrace means disabling, the inc variable
+         *   gets inversed.
+         */
+        if (filter_hash) {
+                hash = ops->filter_hash;
+                other_hash = ops->notrace_hash;
+                if (!hash->count)
+                        all = 1;
+        } else {
+                inc = !inc;
+                hash = ops->notrace_hash;
+                other_hash = ops->filter_hash;
+                /*
+                 * If the notrace hash has no items,
+                 * then there's nothing to do.
+                 */
+                if (!hash->count)
+                        return;
+        }
+
+        do_for_each_ftrace_rec(pg, rec) {
+                int in_other_hash = 0;
+                int in_hash = 0;
+                int match = 0;
+
+                if (all) {
+                        /*
+                         * Only the filter_hash affects all records.
+                         * Update if the record is not in the notrace hash.
+                         */
+                        if (!ftrace_lookup_ip(other_hash, rec->ip))
+                                match = 1;
+                } else {
+                        in_hash = !!ftrace_lookup_ip(hash, rec->ip);
+                        in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip);
+
+                        /*
+                         *
+                         */
+                        if (filter_hash && in_hash && !in_other_hash)
+                                match = 1;
+                        else if (!filter_hash && in_hash &&
+                                 (in_other_hash || !other_hash->count))
+                                match = 1;
+                }
+                if (!match)
+                        continue;
+
+                if (inc) {
+                        rec->flags++;
+                        if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == FTRACE_REF_MAX))
+                                return;
+                } else {
+                        if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
+                                return;
+                        rec->flags--;
+                }
+                count++;
+                /* Shortcut, if we handled all records, we are done. */
+                if (!all && count == hash->count)
+                        return;
+        } while_for_each_ftrace_rec();
+}
+
+static void ftrace_hash_rec_disable(struct ftrace_ops *ops,
+                                    int filter_hash)
+{
+        __ftrace_hash_rec_update(ops, filter_hash, 0);
+}
+
+static void ftrace_hash_rec_enable(struct ftrace_ops *ops,
+                                   int filter_hash)
+{
+        __ftrace_hash_rec_update(ops, filter_hash, 1);
+}
+
 static void ftrace_free_rec(struct dyn_ftrace *rec)
 {
         rec->freelist = ftrace_free_records;
@@ -1276,26 +1379,24 @@ int ftrace_text_reserved(void *start, void *end)
 static int
 __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 {
-        struct ftrace_ops *ops = &global_ops;
         unsigned long ftrace_addr;
         unsigned long flag = 0UL;
 
         ftrace_addr = (unsigned long)FTRACE_ADDR;
 
         /*
-         * If this record is not to be traced or we want to disable it,
-         * then disable it.
+         * If we are enabling tracing:
          *
-         * If we want to enable it and filtering is off, then enable it.
+         *   If the record has a ref count, then we need to enable it
+         *   because someone is using it.
          *
-         * If we want to enable it and filtering is on, enable it only if
-         * it's filtered
+         *   Otherwise we make sure its disabled.
+         *
+         * If we are disabling tracing, then disable all records that
+         * are enabled.
          */
-        if (enable && !ftrace_lookup_ip(ops->notrace_hash, rec->ip)) {
-                if (!ops->filter_hash->count ||
-                    ftrace_lookup_ip(ops->filter_hash, rec->ip))
-                        flag = FTRACE_FL_ENABLED;
-        }
+        if (enable && (rec->flags & ~FTRACE_FL_MASK))
+                flag = FTRACE_FL_ENABLED;
 
         /* If the state of this record hasn't changed, then do nothing */
         if ((rec->flags & FTRACE_FL_ENABLED) == flag)
@@ -1423,17 +1524,25 @@ static void ftrace_startup_enable(int command)
 
 static void ftrace_startup(int command)
 {
+        struct ftrace_ops *ops = &global_ops;
+
         if (unlikely(ftrace_disabled))
                 return;
 
         ftrace_start_up++;
         command |= FTRACE_ENABLE_CALLS;
 
+        ops->flags |= FTRACE_OPS_FL_ENABLED;
+        if (ftrace_start_up == 1)
+                ftrace_hash_rec_enable(ops, 1);
+
         ftrace_startup_enable(command);
 }
 
 static void ftrace_shutdown(int command)
 {
+        struct ftrace_ops *ops = &global_ops;
+
         if (unlikely(ftrace_disabled))
                 return;
 
@@ -1446,7 +1555,12 @@ static void ftrace_shutdown(int command)
         WARN_ON_ONCE(ftrace_start_up < 0);
 
         if (!ftrace_start_up)
+                ftrace_hash_rec_disable(ops, 1);
+
+        if (!ftrace_start_up) {
                 command |= FTRACE_DISABLE_CALLS;
+                ops->flags &= ~FTRACE_OPS_FL_ENABLED;
+        }
 
         if (saved_ftrace_func != ftrace_trace_function) {
                 saved_ftrace_func = ftrace_trace_function;
@@ -2668,6 +2782,7 @@ ftrace_regex_release(struct inode *inode, struct file *file)
         struct ftrace_iterator *iter;
         struct ftrace_hash **orig_hash;
         struct trace_parser *parser;
+        int filter_hash;
         int ret;
 
         mutex_lock(&ftrace_regex_lock);
@@ -2687,15 +2802,26 @@ ftrace_regex_release(struct inode *inode, struct file *file)
         trace_parser_put(parser);
 
         if (file->f_mode & FMODE_WRITE) {
-                if (iter->flags & FTRACE_ITER_NOTRACE)
-                        orig_hash = &iter->ops->notrace_hash;
-                else
+                filter_hash = !!(iter->flags & FTRACE_ITER_FILTER);
+
+                if (filter_hash)
                         orig_hash = &iter->ops->filter_hash;
+                else
+                        orig_hash = &iter->ops->notrace_hash;
 
                 mutex_lock(&ftrace_lock);
+                /*
+                 * Remove the current set, update the hash and add
+                 * them back.
+                 */
+                ftrace_hash_rec_disable(iter->ops, filter_hash);
                 ret = ftrace_hash_move(orig_hash, iter->hash);
-                if (!ret && ftrace_start_up && ftrace_enabled)
-                        ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+                if (!ret) {
+                        ftrace_hash_rec_enable(iter->ops, filter_hash);
+                        if (iter->ops->flags & FTRACE_OPS_FL_ENABLED
+                            && ftrace_enabled)
+                                ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+                }
                 mutex_unlock(&ftrace_lock);
         }
         free_ftrace_hash(iter->hash);