1 files changed, 96 insertions, 48 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0d88ce9b9fb8..f3dadae83883 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -381,12 +381,19 @@ static int function_stat_show(struct seq_file *m, void *v)
 {
         struct ftrace_profile *rec = v;
         char str[KSYM_SYMBOL_LEN];
+        int ret = 0;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-        static DEFINE_MUTEX(mutex);
         static struct trace_seq s;
         unsigned long long avg;
         unsigned long long stddev;
 #endif
+        mutex_lock(&ftrace_profile_lock);
+
+        /* we raced with function_profile_reset() */
+        if (unlikely(rec->counter == 0)) {
+                ret = -EBUSY;
+                goto out;
+        }
 
         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
         seq_printf(m, "  %-30.30s  %10lu", str, rec->counter);
@@ -408,7 +415,6 @@ static int function_stat_show(struct seq_file *m, void *v)
                 do_div(stddev, (rec->counter - 1) * 1000);
         }
 
-        mutex_lock(&mutex);
         trace_seq_init(&s);
         trace_print_graph_duration(rec->time, &s);
         trace_seq_puts(&s, "    ");
@@ -416,11 +422,12 @@ static int function_stat_show(struct seq_file *m, void *v)
         trace_seq_puts(&s, "    ");
         trace_print_graph_duration(stddev, &s);
         trace_print_seq(m, &s);
-        mutex_unlock(&mutex);
 #endif
         seq_putc(m, '\n');
+out:
+        mutex_unlock(&ftrace_profile_lock);
 
-        return 0;
+        return ret;
 }
 
 static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
@@ -793,6 +800,7 @@ static const struct file_operations ftrace_profile_fops = {
         .open           = tracing_open_generic,
         .read           = ftrace_profile_read,
         .write          = ftrace_profile_write,
+        .llseek         = default_llseek,
 };
 
 /* used to initialize the real stat files */
@@ -877,10 +885,8 @@ enum {
         FTRACE_ENABLE_CALLS             = (1 << 0),
         FTRACE_DISABLE_CALLS            = (1 << 1),
         FTRACE_UPDATE_TRACE_FUNC        = (1 << 2),
-        FTRACE_ENABLE_MCOUNT            = (1 << 3),
-        FTRACE_DISABLE_MCOUNT           = (1 << 4),
-        FTRACE_START_FUNC_RET           = (1 << 5),
-        FTRACE_STOP_FUNC_RET            = (1 << 6),
+        FTRACE_START_FUNC_RET           = (1 << 3),
+        FTRACE_STOP_FUNC_RET            = (1 << 4),
 };
 
 static int ftrace_filtered;
@@ -1219,8 +1225,6 @@ static void ftrace_shutdown(int command)
 
 static void ftrace_startup_sysctl(void)
 {
-        int command = FTRACE_ENABLE_MCOUNT;
-
         if (unlikely(ftrace_disabled))
                 return;
 
@@ -1228,23 +1232,17 @@ static void ftrace_startup_sysctl(void)
         saved_ftrace_func = NULL;
         /* ftrace_start_up is true if we want ftrace running */
         if (ftrace_start_up)
-                command |= FTRACE_ENABLE_CALLS;
-
-        ftrace_run_update_code(command);
+                ftrace_run_update_code(FTRACE_ENABLE_CALLS);
 }
 
 static void ftrace_shutdown_sysctl(void)
 {
-        int command = FTRACE_DISABLE_MCOUNT;
-
         if (unlikely(ftrace_disabled))
                 return;
 
         /* ftrace_start_up is true if ftrace is running */
         if (ftrace_start_up)
-                command |= FTRACE_DISABLE_CALLS;
-
-        ftrace_run_update_code(command);
+                ftrace_run_update_code(FTRACE_DISABLE_CALLS);
 }
 
 static cycle_t          ftrace_update_time;
@@ -1361,24 +1359,29 @@ enum {
 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
 
 struct ftrace_iterator {
-        struct ftrace_page      *pg;
-        int                     hidx;
-        int                     idx;
-        unsigned                flags;
-        struct trace_parser     parser;
+        loff_t                          pos;
+        loff_t                          func_pos;
+        struct ftrace_page              *pg;
+        struct dyn_ftrace               *func;
+        struct ftrace_func_probe        *probe;
+        struct trace_parser             parser;
+        int                             hidx;
+        int                             idx;
+        unsigned                        flags;
 };
 
 static void *
-t_hash_next(struct seq_file *m, void *v, loff_t *pos)
+t_hash_next(struct seq_file *m, loff_t *pos)
 {
         struct ftrace_iterator *iter = m->private;
-        struct hlist_node *hnd = v;
+        struct hlist_node *hnd = NULL;
         struct hlist_head *hhd;
 
-        WARN_ON(!(iter->flags & FTRACE_ITER_HASH));
-
         (*pos)++;
+        iter->pos = *pos;
 
+        if (iter->probe)
+                hnd = &iter->probe->node;
  retry:
         if (iter->hidx >= FTRACE_FUNC_HASHSIZE)
                 return NULL;
@@ -1401,7 +1404,12 @@ t_hash_next(struct seq_file *m, void *v, loff_t *pos)
                 }
         }
 
-        return hnd;
+        if (WARN_ON_ONCE(!hnd))
+                return NULL;
+
+        iter->probe = hlist_entry(hnd, struct ftrace_func_probe, node);
+
+        return iter;
 }
 
 static void *t_hash_start(struct seq_file *m, loff_t *pos)
@@ -1410,26 +1418,32 @@ static void *t_hash_start(struct seq_file *m, loff_t *pos)
         void *p = NULL;
         loff_t l;
 
-        if (!(iter->flags & FTRACE_ITER_HASH))
-                *pos = 0;
-
-        iter->flags |= FTRACE_ITER_HASH;
+        if (iter->func_pos > *pos)
+                return NULL;
 
         iter->hidx = 0;
-        for (l = 0; l <= *pos; ) {
-                p = t_hash_next(m, p, &l);
+        for (l = 0; l <= (*pos - iter->func_pos); ) {
+                p = t_hash_next(m, &l);
                 if (!p)
                         break;
         }
-        return p;
+        if (!p)
+                return NULL;
+
+        /* Only set this if we have an item */
+        iter->flags |= FTRACE_ITER_HASH;
+
+        return iter;
 }
 
-static int t_hash_show(struct seq_file *m, void *v)
+static int
+t_hash_show(struct seq_file *m, struct ftrace_iterator *iter)
 {
         struct ftrace_func_probe *rec;
-        struct hlist_node *hnd = v;
 
-        rec = hlist_entry(hnd, struct ftrace_func_probe, node);
+        rec = iter->probe;
+        if (WARN_ON_ONCE(!rec))
+                return -EIO;
 
         if (rec->ops->print)
                 return rec->ops->print(m, rec->ip, rec->ops, rec->data);
@@ -1450,12 +1464,13 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
         struct dyn_ftrace *rec = NULL;
 
         if (iter->flags & FTRACE_ITER_HASH)
-                return t_hash_next(m, v, pos);
+                return t_hash_next(m, pos);
 
         (*pos)++;
+        iter->pos = *pos;
 
         if (iter->flags & FTRACE_ITER_PRINTALL)
-                return NULL;
+                return t_hash_start(m, pos);
 
  retry:
         if (iter->idx >= iter->pg->index) {
@@ -1484,7 +1499,20 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
                 }
         }
 
-        return rec;
+        if (!rec)
+                return t_hash_start(m, pos);
+
+        iter->func_pos = *pos;
+        iter->func = rec;
+
+        return iter;
+}
+
+static void reset_iter_read(struct ftrace_iterator *iter)
+{
+        iter->pos = 0;
+        iter->func_pos = 0;
+        iter->flags &= ~(FTRACE_ITER_PRINTALL & FTRACE_ITER_HASH);
 }
 
 static void *t_start(struct seq_file *m, loff_t *pos)
@@ -1495,6 +1523,12 @@ static void *t_start(struct seq_file *m, loff_t *pos)
 
         mutex_lock(&ftrace_lock);
         /*
+         * If an lseek was done, then reset and start from beginning.
+         */
+        if (*pos < iter->pos)
+                reset_iter_read(iter);
+
+        /*
          * For set_ftrace_filter reading, if we have the filter
          * off, we can short cut and just print out that all
          * functions are enabled.
@@ -1503,12 +1537,19 @@ static void *t_start(struct seq_file *m, loff_t *pos)
                 if (*pos > 0)
                         return t_hash_start(m, pos);
                 iter->flags |= FTRACE_ITER_PRINTALL;
+                /* reset in case of seek/pread */
+                iter->flags &= ~FTRACE_ITER_HASH;
                 return iter;
         }
 
         if (iter->flags & FTRACE_ITER_HASH)
                 return t_hash_start(m, pos);
 
+        /*
+         * Unfortunately, we need to restart at ftrace_pages_start
+         * every time we let go of the ftrace_mutex. This is because
+         * those pointers can change without the lock.
+         */
         iter->pg = ftrace_pages_start;
         iter->idx = 0;
         for (l = 0; l <= *pos; ) {
@@ -1517,10 +1558,14 @@ static void *t_start(struct seq_file *m, loff_t *pos)
                         break;
         }
 
-        if (!p && iter->flags & FTRACE_ITER_FILTER)
-                return t_hash_start(m, pos);
+        if (!p) {
+                if (iter->flags & FTRACE_ITER_FILTER)
+                        return t_hash_start(m, pos);
 
-        return p;
+                return NULL;
+        }
+
+        return iter;
 }
 
 static void t_stop(struct seq_file *m, void *p)
@@ -1531,16 +1576,18 @@ static void t_stop(struct seq_file *m, void *p)
 static int t_show(struct seq_file *m, void *v)
 {
         struct ftrace_iterator *iter = m->private;
-        struct dyn_ftrace *rec = v;
+        struct dyn_ftrace *rec;
 
         if (iter->flags & FTRACE_ITER_HASH)
-                return t_hash_show(m, v);
+                return t_hash_show(m, iter);
 
         if (iter->flags & FTRACE_ITER_PRINTALL) {
                 seq_printf(m, "#### all functions enabled ####\n");
                 return 0;
         }
 
+        rec = iter->func;
+
         if (!rec)
                 return 0;
 
@@ -1592,8 +1639,8 @@ ftrace_failures_open(struct inode *inode, struct file *file)
 
         ret = ftrace_avail_open(inode, file);
         if (!ret) {
-                m = (struct seq_file *)file->private_data;
-                iter = (struct ftrace_iterator *)m->private;
+                m = file->private_data;
+                iter = m->private;
                 iter->flags = FTRACE_ITER_FAILURES;
         }
 
@@ -2623,6 +2670,7 @@ static const struct file_operations ftrace_graph_fops = {
         .read           = seq_read,
         .write          = ftrace_graph_write,
         .release        = ftrace_graph_release,
+        .llseek         = seq_lseek,
 };
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */