diff options
Diffstat (limited to 'kernel/trace/trace_printk.c')
| -rw-r--r-- | kernel/trace/trace_printk.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c index 6fd4ffd042f..2900817ba65 100644 --- a/kernel/trace/trace_printk.c +++ b/kernel/trace/trace_printk.c @@ -51,6 +51,10 @@ void hold_module_trace_bprintk_format(const char **start, const char **end) const char **iter; char *fmt; + /* allocate the trace_printk per cpu buffers */ + if (start != end) + trace_printk_init_buffers(); + mutex_lock(&btrace_mutex); for (iter = start; iter < end; iter++) { struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter); @@ -240,12 +244,31 @@ static const char **find_next(void *v, loff_t *pos) { const char **fmt = v; int start_index; + int last_index; start_index = __stop___trace_bprintk_fmt - __start___trace_bprintk_fmt; if (*pos < start_index) return __start___trace_bprintk_fmt + *pos; + /* + * The __tracepoint_str section is treated the same as the + * __trace_printk_fmt section. The difference is that the + * __trace_printk_fmt section should only be used by trace_printk() + * in a debugging environment, as if anything exists in that section + * the trace_prink() helper buffers are allocated, which would just + * waste space in a production environment. + * + * The __tracepoint_str sections on the other hand are used by + * tracepoints which need to map pointers to their strings to + * the ASCII text for userspace. + */ + last_index = start_index; + start_index = __stop___tracepoint_str - __start___tracepoint_str; + + if (*pos < last_index + start_index) + return __start___tracepoint_str + (*pos - last_index); + return find_next_mod_format(start_index, v, fmt, pos); } |