4 files changed, 268 insertions, 229 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index ee24fa1935ac..d3406346ced6 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -39,16 +39,20 @@
 #include "trace_stat.h"
 
 #define FTRACE_WARN_ON(cond)                    \
-        do {                                    \
-                if (WARN_ON(cond))              \
+        ({                                      \
+                int ___r = cond;                \
+                if (WARN_ON(___r))              \
                         ftrace_kill();          \
-        } while (0)
+                ___r;                           \
+        })
 
 #define FTRACE_WARN_ON_ONCE(cond)               \
-        do {                                    \
-                if (WARN_ON_ONCE(cond))         \
+        ({                                      \
+                int ___r = cond;                \
+                if (WARN_ON_ONCE(___r))         \
                         ftrace_kill();          \
-        } while (0)
+                ___r;                           \
+        })
 
 /* hash bits for specific function selection */
 #define FTRACE_HASH_BITS 7
@@ -147,6 +151,34 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
 }
 #endif
 
+static void update_ftrace_function(void)
+{
+        ftrace_func_t func;
+
+        /*
+         * If there's only one function registered, then call that
+         * function directly. Otherwise, we need to iterate over the
+         * registered callers.
+         */
+        if (ftrace_list == &ftrace_list_end ||
+            ftrace_list->next == &ftrace_list_end)
+                func = ftrace_list->func;
+        else
+                func = ftrace_list_func;
+
+        /* If we filter on pids, update to use the pid function */
+        if (!list_empty(&ftrace_pids)) {
+                set_ftrace_pid_function(func);
+                func = ftrace_pid_func;
+        }
+#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
+        ftrace_trace_function = func;
+#else
+        __ftrace_trace_function = func;
+        ftrace_trace_function = ftrace_test_stop_func;
+#endif
+}
+
 static int __register_ftrace_function(struct ftrace_ops *ops)
 {
         ops->next = ftrace_list;
@@ -158,30 +190,8 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
          */
         rcu_assign_pointer(ftrace_list, ops);
 
-        if (ftrace_enabled) {
-                ftrace_func_t func;
-
-                if (ops->next == &ftrace_list_end)
-                        func = ops->func;
-                else
-                        func = ftrace_list_func;
-
-                if (!list_empty(&ftrace_pids)) {
-                        set_ftrace_pid_function(func);
-                        func = ftrace_pid_func;
-                }
-
-                /*
-                 * For one func, simply call it directly.
-                 * For more than one func, call the chain.
-                 */
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
-                ftrace_trace_function = func;
-#else
-                __ftrace_trace_function = func;
-                ftrace_trace_function = ftrace_test_stop_func;
-#endif
-        }
+        if (ftrace_enabled)
+                update_ftrace_function();
 
         return 0;
 }
@@ -209,52 +219,19 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
 
         *p = (*p)->next;
 
-        if (ftrace_enabled) {
-                /* If we only have one func left, then call that directly */
-                if (ftrace_list->next == &ftrace_list_end) {
-                        ftrace_func_t func = ftrace_list->func;
-
-                        if (!list_empty(&ftrace_pids)) {
-                                set_ftrace_pid_function(func);
-                                func = ftrace_pid_func;
-                        }
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
-                        ftrace_trace_function = func;
-#else
-                        __ftrace_trace_function = func;
-#endif
-                }
-        }
+        if (ftrace_enabled)
+                update_ftrace_function();
 
         return 0;
 }
 
 static void ftrace_update_pid_func(void)
 {
-        ftrace_func_t func;
-
+        /* Only do something if we are tracing something */
         if (ftrace_trace_function == ftrace_stub)
                 return;
 
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
-        func = ftrace_trace_function;
-#else
-        func = __ftrace_trace_function;
-#endif
-
-        if (!list_empty(&ftrace_pids)) {
-                set_ftrace_pid_function(func);
-                func = ftrace_pid_func;
-        } else {
-                if (func == ftrace_pid_func)
-                        func = ftrace_pid_function;
-        }
-
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
-        ftrace_trace_function = func;
-#else
-        __ftrace_trace_function = func;
-#endif
+        update_ftrace_function();
 }
 
 #ifdef CONFIG_FUNCTION_PROFILER
@@ -1079,19 +1056,16 @@ static void ftrace_replace_code(int enable)
         struct ftrace_page *pg;
         int failed;
 
+        if (unlikely(ftrace_disabled))
+                return;
+
         do_for_each_ftrace_rec(pg, rec) {
-                /*
-                 * Skip over free records, records that have
-                 * failed and not converted.
-                 */
-                if (rec->flags & FTRACE_FL_FREE ||
-                    rec->flags & FTRACE_FL_FAILED ||
-                    !(rec->flags & FTRACE_FL_CONVERTED))
+                /* Skip over free records */
+                if (rec->flags & FTRACE_FL_FREE)
                         continue;
 
                 failed = __ftrace_replace_code(rec, enable);
                 if (failed) {
-                        rec->flags |= FTRACE_FL_FAILED;
                         ftrace_bug(failed, rec->ip);
                         /* Stop processing */
                         return;
@@ -1107,10 +1081,12 @@ ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
 
         ip = rec->ip;
 
+        if (unlikely(ftrace_disabled))
+                return 0;
+
         ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
         if (ret) {
                 ftrace_bug(ret, ip);
-                rec->flags |= FTRACE_FL_FAILED;
                 return 0;
         }
         return 1;
@@ -1273,10 +1249,10 @@ static int ftrace_update_code(struct module *mod)
                  */
                 if (!ftrace_code_disable(mod, p)) {
                         ftrace_free_rec(p);
-                        continue;
+                        /* Game over */
+                        break;
                 }
 
-                p->flags |= FTRACE_FL_CONVERTED;
                 ftrace_update_cnt++;
 
                 /*
@@ -1351,9 +1327,8 @@ static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
 enum {
         FTRACE_ITER_FILTER      = (1 << 0),
         FTRACE_ITER_NOTRACE     = (1 << 1),
-        FTRACE_ITER_FAILURES    = (1 << 2),
-        FTRACE_ITER_PRINTALL    = (1 << 3),
-        FTRACE_ITER_HASH        = (1 << 4),
+        FTRACE_ITER_PRINTALL    = (1 << 2),
+        FTRACE_ITER_HASH        = (1 << 3),
 };
 
 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
@@ -1463,6 +1438,9 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
         struct ftrace_iterator *iter = m->private;
         struct dyn_ftrace *rec = NULL;
 
+        if (unlikely(ftrace_disabled))
+                return NULL;
+
         if (iter->flags & FTRACE_ITER_HASH)
                 return t_hash_next(m, pos);
 
@@ -1483,12 +1461,6 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
                 rec = &iter->pg->records[iter->idx++];
                 if ((rec->flags & FTRACE_FL_FREE) ||
 
-                    (!(iter->flags & FTRACE_ITER_FAILURES) &&
-                     (rec->flags & FTRACE_FL_FAILED)) ||
-
-                    ((iter->flags & FTRACE_ITER_FAILURES) &&
-                     !(rec->flags & FTRACE_FL_FAILED)) ||
-
                     ((iter->flags & FTRACE_ITER_FILTER) &&
                      !(rec->flags & FTRACE_FL_FILTER)) ||
 
@@ -1521,6 +1493,10 @@ static void *t_start(struct seq_file *m, loff_t *pos)
         loff_t l;
 
         mutex_lock(&ftrace_lock);
+
+        if (unlikely(ftrace_disabled))
+                return NULL;
+
         /*
          * If an lseek was done, then reset and start from beginning.
          */
@@ -1629,24 +1605,6 @@ ftrace_avail_open(struct inode *inode, struct file *file)
         return ret;
 }
 
-static int
-ftrace_failures_open(struct inode *inode, struct file *file)
-{
-        int ret;
-        struct seq_file *m;
-        struct ftrace_iterator *iter;
-
-        ret = ftrace_avail_open(inode, file);
-        if (!ret) {
-                m = file->private_data;
-                iter = m->private;
-                iter->flags = FTRACE_ITER_FAILURES;
-        }
-
-        return ret;
-}
-
-
 static void ftrace_filter_reset(int enable)
 {
         struct ftrace_page *pg;
@@ -1657,8 +1615,6 @@ static void ftrace_filter_reset(int enable)
         if (enable)
                 ftrace_filtered = 0;
         do_for_each_ftrace_rec(pg, rec) {
-                if (rec->flags & FTRACE_FL_FAILED)
-                        continue;
                 rec->flags &= ~type;
         } while_for_each_ftrace_rec();
         mutex_unlock(&ftrace_lock);
@@ -1760,42 +1716,63 @@ static int ftrace_match(char *str, char *regex, int len, int type)
         return matched;
 }
 
+static void
+update_record(struct dyn_ftrace *rec, unsigned long flag, int not)
+{
+        if (not)
+                rec->flags &= ~flag;
+        else
+                rec->flags |= flag;
+}
+
 static int
-ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)
+ftrace_match_record(struct dyn_ftrace *rec, char *mod,
+                    char *regex, int len, int type)
 {
         char str[KSYM_SYMBOL_LEN];
+        char *modname;
+
+        kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);
+
+        if (mod) {
+                /* module lookup requires matching the module */
+                if (!modname || strcmp(modname, mod))
+                        return 0;
+
+                /* blank search means to match all funcs in the mod */
+                if (!len)
+                        return 1;
+        }
 
-        kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
         return ftrace_match(str, regex, len, type);
 }
 
-static int ftrace_match_records(char *buff, int len, int enable)
+static int match_records(char *buff, int len, char *mod, int enable, int not)
 {
-        unsigned int search_len;
+        unsigned search_len = 0;
         struct ftrace_page *pg;
         struct dyn_ftrace *rec;
+        int type = MATCH_FULL;
+        char *search = buff;
         unsigned long flag;
-        char *search;
-        int type;
-        int not;
         int found = 0;
 
-        flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
-        type = filter_parse_regex(buff, len, &search, &not);
+        if (len) {
+                type = filter_parse_regex(buff, len, &search, &not);
+                search_len = strlen(search);
+        }
 
-        search_len = strlen(search);
+        flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
 
         mutex_lock(&ftrace_lock);
-        do_for_each_ftrace_rec(pg, rec) {
 
-                if (rec->flags & FTRACE_FL_FAILED)
-                        continue;
+        if (unlikely(ftrace_disabled))
+                goto out_unlock;
 
-                if (ftrace_match_record(rec, search, search_len, type)) {
-                        if (not)
-                                rec->flags &= ~flag;
-                        else
-                                rec->flags |= flag;
+        do_for_each_ftrace_rec(pg, rec) {
+
+                if (ftrace_match_record(rec, mod, search, search_len, type)) {
+                        update_record(rec, flag, not);
                         found = 1;
                 }
                 /*
@@ -1804,43 +1781,23 @@ static int ftrace_match_records(char *buff, int len, int enable)
                  */
                 if (enable && (rec->flags & FTRACE_FL_FILTER))
                         ftrace_filtered = 1;
+
         } while_for_each_ftrace_rec();
+ out_unlock:
         mutex_unlock(&ftrace_lock);
 
         return found;
 }
 
 static int
-ftrace_match_module_record(struct dyn_ftrace *rec, char *mod,
-                           char *regex, int len, int type)
+ftrace_match_records(char *buff, int len, int enable)
 {
-        char str[KSYM_SYMBOL_LEN];
-        char *modname;
-
-        kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);
-
-        if (!modname || strcmp(modname, mod))
-                return 0;
-
-        /* blank search means to match all funcs in the mod */
-        if (len)
-                return ftrace_match(str, regex, len, type);
-        else
-                return 1;
+        return match_records(buff, len, NULL, enable, 0);
 }
 
 static int ftrace_match_module_records(char *buff, char *mod, int enable)
 {
-        unsigned search_len = 0;
-        struct ftrace_page *pg;
-        struct dyn_ftrace *rec;
-        int type = MATCH_FULL;
-        char *search = buff;
-        unsigned long flag;
         int not = 0;
-        int found = 0;
-
-        flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
 
         /* blank or '*' mean the same */
         if (strcmp(buff, "*") == 0)
@@ -1852,32 +1809,7 @@ static int ftrace_match_module_records(char *buff, char *mod, int enable)
                 not = 1;
         }
 
-        if (strlen(buff)) {
-                type = filter_parse_regex(buff, strlen(buff), &search, &not);
-                search_len = strlen(search);
-        }
-
-        mutex_lock(&ftrace_lock);
-        do_for_each_ftrace_rec(pg, rec) {
-
-                if (rec->flags & FTRACE_FL_FAILED)
-                        continue;
-
-                if (ftrace_match_module_record(rec, mod,
-                                               search, search_len, type)) {
-                        if (not)
-                                rec->flags &= ~flag;
-                        else
-                                rec->flags |= flag;
-                        found = 1;
-                }
-                if (enable && (rec->flags & FTRACE_FL_FILTER))
-                        ftrace_filtered = 1;
-
-        } while_for_each_ftrace_rec();
-        mutex_unlock(&ftrace_lock);
-
-        return found;
+        return match_records(buff, strlen(buff), mod, enable, not);
 }
 
 /*
@@ -2029,12 +1961,13 @@ register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
                 return -EINVAL;
 
         mutex_lock(&ftrace_lock);
-        do_for_each_ftrace_rec(pg, rec) {
 
-                if (rec->flags & FTRACE_FL_FAILED)
-                        continue;
+        if (unlikely(ftrace_disabled))
+                goto out_unlock;
 
-                if (!ftrace_match_record(rec, search, len, type))
+        do_for_each_ftrace_rec(pg, rec) {
+
+                if (!ftrace_match_record(rec, NULL, search, len, type))
                         continue;
 
                 entry = kmalloc(sizeof(*entry), GFP_KERNEL);
@@ -2239,6 +2172,10 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
 
         mutex_lock(&ftrace_regex_lock);
 
+        ret = -ENODEV;
+        if (unlikely(ftrace_disabled))
+                goto out_unlock;
+
         if (file->f_mode & FMODE_READ) {
                 struct seq_file *m = file->private_data;
                 iter = m->private;
@@ -2413,14 +2350,16 @@ ftrace_regex_release(struct inode *inode, struct file *file, int enable)
                 ftrace_match_records(parser->buffer, parser->idx, enable);
         }
 
-        mutex_lock(&ftrace_lock);
-        if (ftrace_start_up && ftrace_enabled)
-                ftrace_run_update_code(FTRACE_ENABLE_CALLS);
-        mutex_unlock(&ftrace_lock);
-
         trace_parser_put(parser);
         kfree(iter);
 
+        if (file->f_mode & FMODE_WRITE) {
+                mutex_lock(&ftrace_lock);
+                if (ftrace_start_up && ftrace_enabled)
+                        ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+                mutex_unlock(&ftrace_lock);
+        }
+
         mutex_unlock(&ftrace_regex_lock);
         return 0;
 }
@@ -2444,13 +2383,6 @@ static const struct file_operations ftrace_avail_fops = {
         .release = seq_release_private,
 };
 
-static const struct file_operations ftrace_failures_fops = {
-        .open = ftrace_failures_open,
-        .read = seq_read,
-        .llseek = seq_lseek,
-        .release = seq_release_private,
-};
-
 static const struct file_operations ftrace_filter_fops = {
         .open = ftrace_filter_open,
         .read = seq_read,
@@ -2573,9 +2505,6 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)
         bool exists;
         int i;
 
-        if (ftrace_disabled)
-                return -ENODEV;
-
         /* decode regex */
         type = filter_parse_regex(buffer, strlen(buffer), &search, &not);
         if (!not && *idx >= FTRACE_GRAPH_MAX_FUNCS)
@@ -2584,12 +2513,18 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)
         search_len = strlen(search);
 
         mutex_lock(&ftrace_lock);
+
+        if (unlikely(ftrace_disabled)) {
+                mutex_unlock(&ftrace_lock);
+                return -ENODEV;
+        }
+
         do_for_each_ftrace_rec(pg, rec) {
 
-                if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
+                if (rec->flags & FTRACE_FL_FREE)
                         continue;
 
-                if (ftrace_match_record(rec, search, search_len, type)) {
+                if (ftrace_match_record(rec, NULL, search, search_len, type)) {
                         /* if it is in the array */
                         exists = false;
                         for (i = 0; i < *idx; i++) {
@@ -2679,9 +2614,6 @@ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
         trace_create_file("available_filter_functions", 0444,
                         d_tracer, NULL, &ftrace_avail_fops);
 
-        trace_create_file("failures", 0444,
-                        d_tracer, NULL, &ftrace_failures_fops);
-
         trace_create_file("set_ftrace_filter", 0644, d_tracer,
                         NULL, &ftrace_filter_fops);
 
@@ -2703,7 +2635,6 @@ static int ftrace_process_locs(struct module *mod,
 {
         unsigned long *p;
         unsigned long addr;
-        unsigned long flags;
 
         mutex_lock(&ftrace_lock);
         p = start;
@@ -2720,10 +2651,7 @@ static int ftrace_process_locs(struct module *mod,
                 ftrace_record_ip(addr);
         }
 
-        /* disable interrupts to prevent kstop machine */
-        local_irq_save(flags);
         ftrace_update_code(mod);
-        local_irq_restore(flags);
         mutex_unlock(&ftrace_lock);
 
         return 0;
@@ -2735,10 +2663,11 @@ void ftrace_release_mod(struct module *mod)
         struct dyn_ftrace *rec;
         struct ftrace_page *pg;
 
+        mutex_lock(&ftrace_lock);
+
         if (ftrace_disabled)
-                return;
+                goto out_unlock;
 
-        mutex_lock(&ftrace_lock);
         do_for_each_ftrace_rec(pg, rec) {
                 if (within_module_core(rec->ip, mod)) {
                         /*
@@ -2749,6 +2678,7 @@ void ftrace_release_mod(struct module *mod)
                         ftrace_free_rec(rec);
                 }
         } while_for_each_ftrace_rec();
+ out_unlock:
         mutex_unlock(&ftrace_lock);
 }
 
@@ -3143,16 +3073,17 @@ void ftrace_kill(void)
  */
 int register_ftrace_function(struct ftrace_ops *ops)
 {
-        int ret;
-
-        if (unlikely(ftrace_disabled))
-                return -1;
+        int ret = -1;
 
         mutex_lock(&ftrace_lock);
 
+        if (unlikely(ftrace_disabled))
+                goto out_unlock;
+
         ret = __register_ftrace_function(ops);
         ftrace_startup(0);
 
+ out_unlock:
         mutex_unlock(&ftrace_lock);
         return ret;
 }
@@ -3180,14 +3111,14 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
                      void __user *buffer, size_t *lenp,
                      loff_t *ppos)
 {
-        int ret;
-
-        if (unlikely(ftrace_disabled))
-                return -ENODEV;
+        int ret = -ENODEV;
 
         mutex_lock(&ftrace_lock);
 
-        ret  = proc_dointvec(table, write, buffer, lenp, ppos);
+        if (unlikely(ftrace_disabled))
+                goto out;
+
+        ret = proc_dointvec(table, write, buffer, lenp, ppos);
 
         if (ret || !write || (last_ftrace_enabled == !!ftrace_enabled))
                 goto out;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1cb49be7c7fb..ee9c921d7f21 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2014,9 +2014,10 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
 {
         enum print_line_t ret;
 
-        if (iter->lost_events)
-                trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
-                                 iter->cpu, iter->lost_events);
+        if (iter->lost_events &&
+            !trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
+                                 iter->cpu, iter->lost_events))
+                return TRACE_TYPE_PARTIAL_LINE;
 
         if (iter->trace && iter->trace->print_line) {
                 ret = iter->trace->print_line(iter);
@@ -3230,6 +3231,14 @@ waitagain:
 
                 if (iter->seq.len >= cnt)
                         break;
+
+                /*
+                 * Setting the full flag means we reached the trace_seq buffer
+                 * size and we should leave by partial output condition above.
+                 * One of the trace_seq_* functions is not used properly.
+                 */
+                WARN_ONCE(iter->seq.full, "full flag set for trace type %d",
+                          iter->ent->type);
         }
         trace_access_unlock(iter->cpu_file);
         trace_event_read_unlock();
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 456be9063c2d..cf535ccedc86 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -830,6 +830,9 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_event);
 enum print_line_t trace_nop_print(struct trace_iterator *iter, int flags,
                                   struct trace_event *event)
 {
+        if (!trace_seq_printf(&iter->seq, "type: %d\n", iter->ent->type))
+                return TRACE_TYPE_PARTIAL_LINE;
+
         return TRACE_TYPE_HANDLED;
 }
 
diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index 2547d8813cf0..dff763b7baf1 100644
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -32,7 +32,7 @@ static DEFINE_MUTEX(btrace_mutex);
 
 struct trace_bprintk_fmt {
         struct list_head list;
-        char fmt[0];
+        const char *fmt;
 };
 
 static inline struct trace_bprintk_fmt *lookup_format(const char *fmt)
@@ -49,6 +49,7 @@ static
 void hold_module_trace_bprintk_format(const char **start, const char **end)
 {
         const char **iter;
+        char *fmt;
 
         mutex_lock(&btrace_mutex);
         for (iter = start; iter < end; iter++) {
@@ -58,14 +59,18 @@ void hold_module_trace_bprintk_format(const char **start, const char **end)
                         continue;
                 }
 
-                tb_fmt = kmalloc(offsetof(struct trace_bprintk_fmt, fmt)
-                                + strlen(*iter) + 1, GFP_KERNEL);
-                if (tb_fmt) {
+                tb_fmt = kmalloc(sizeof(*tb_fmt), GFP_KERNEL);
+                if (tb_fmt)
+                        fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL);
+                if (tb_fmt && fmt) {
                         list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);
-                        strcpy(tb_fmt->fmt, *iter);
+                        strcpy(fmt, *iter);
+                        tb_fmt->fmt = fmt;
                         *iter = tb_fmt->fmt;
-                } else
+                } else {
+                        kfree(tb_fmt);
                         *iter = NULL;
+                }
         }
         mutex_unlock(&btrace_mutex);
 }
@@ -84,6 +89,76 @@ static int module_trace_bprintk_format_notify(struct notifier_block *self,
         return 0;
 }
 
+/*
+ * The debugfs/tracing/printk_formats file maps the addresses with
+ * the ASCII formats that are used in the bprintk events in the
+ * buffer. For userspace tools to be able to decode the events from
+ * the buffer, they need to be able to map the address with the format.
+ *
+ * The addresses of the bprintk formats are in their own section
+ * __trace_printk_fmt. But for modules we copy them into a link list.
+ * The code to print the formats and their addresses passes around the
+ * address of the fmt string. If the fmt address passed into the seq
+ * functions is within the kernel core __trace_printk_fmt section, then
+ * it simply uses the next pointer in the list.
+ *
+ * When the fmt pointer is outside the kernel core __trace_printk_fmt
+ * section, then we need to read the link list pointers. The trick is
+ * we pass the address of the string to the seq function just like
+ * we do for the kernel core formats. To get back the structure that
+ * holds the format, we simply use containerof() and then go to the
+ * next format in the list.
+ */
+static const char **
+find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)
+{
+        struct trace_bprintk_fmt *mod_fmt;
+
+        if (list_empty(&trace_bprintk_fmt_list))
+                return NULL;
+
+        /*
+         * v will point to the address of the fmt record from t_next
+         * v will be NULL from t_start.
+         * If this is the first pointer or called from start
+         * then we need to walk the list.
+         */
+        if (!v || start_index == *pos) {
+                struct trace_bprintk_fmt *p;
+
+                /* search the module list */
+                list_for_each_entry(p, &trace_bprintk_fmt_list, list) {
+                        if (start_index == *pos)
+                                return &p->fmt;
+                        start_index++;
+                }
+                /* pos > index */
+                return NULL;
+        }
+
+        /*
+         * v points to the address of the fmt field in the mod list
+         * structure that holds the module print format.
+         */
+        mod_fmt = container_of(v, typeof(*mod_fmt), fmt);
+        if (mod_fmt->list.next == &trace_bprintk_fmt_list)
+                return NULL;
+
+        mod_fmt = container_of(mod_fmt->list.next, typeof(*mod_fmt), list);
+
+        return &mod_fmt->fmt;
+}
+
+static void format_mod_start(void)
+{
+        mutex_lock(&btrace_mutex);
+}
+
+static void format_mod_stop(void)
+{
+        mutex_unlock(&btrace_mutex);
+}
+
 #else /* !CONFIG_MODULES */
 __init static int
 module_trace_bprintk_format_notify(struct notifier_block *self,
@@ -91,6 +166,13 @@ module_trace_bprintk_format_notify(struct notifier_block *self,
 {
         return 0;
 }
+static inline const char **
+find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)
+{
+        return NULL;
+}
+static inline void format_mod_start(void) { }
+static inline void format_mod_stop(void) { }
 #endif /* CONFIG_MODULES */
 
 
@@ -153,20 +235,33 @@ int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap)
 }
 EXPORT_SYMBOL_GPL(__ftrace_vprintk);
 
+static const char **find_next(void *v, loff_t *pos)
+{
+        const char **fmt = v;
+        int start_index;
+
+        if (!fmt)
+                fmt = __start___trace_bprintk_fmt + *pos;
+
+        start_index = __stop___trace_bprintk_fmt - __start___trace_bprintk_fmt;
+
+        if (*pos < start_index)
+                return fmt;
+
+        return find_next_mod_format(start_index, v, fmt, pos);
+}
+
 static void *
 t_start(struct seq_file *m, loff_t *pos)
 {
-        const char **fmt = __start___trace_bprintk_fmt + *pos;
-
-        if ((unsigned long)fmt >= (unsigned long)__stop___trace_bprintk_fmt)
-                return NULL;
-        return fmt;
+        format_mod_start();
+        return find_next(NULL, pos);
 }
 
 static void *t_next(struct seq_file *m, void * v, loff_t *pos)
 {
         (*pos)++;
-        return t_start(m, pos);
+        return find_next(v, pos);
 }
 
 static int t_show(struct seq_file *m, void *v)
@@ -205,6 +300,7 @@ static int t_show(struct seq_file *m, void *v)
 
 static void t_stop(struct seq_file *m, void *p)
 {
+        format_mod_stop();
 }
 
 static const struct seq_operations show_format_seq_ops = {