tracing: Convert trace_printk() formats for module to const char *

The trace_printk() formats for modules do not show up in the
debugfs/tracing/printk_formats file. Only the formats that are
for trace_printk()s that are in the kernel core.

To facilitate the change to add trace_printk() formats from modules
into that file as well, we need to convert the structure that
holds the formats from char fmt[], into const char *fmt,
and allocate them separately.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 11 insertions, 6 deletions

diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index 2547d8813cf0..b8b268158af0 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);
 }