[PATCH 1/2] trace-cmd: [BUGFIX] Initialize handle->options list in tracecmd_attach_cpu_data_fd()

[Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>]

This patch initializes handle->options list in tracecmd_attach_cpu_data_fd().

When recorder sends trace data via network, server recording process is
killed by SIGSEGV from the patch 71484a0854f7. This is because add_options()
uses handle->options list from the patch, but tracecmd_attach_cpu_data_fd()
calling add_options() does not initialize the list in spite of allocation of
new handle. As the result, the server recording process will be killed because
handle->options is cleared to zero in tracecmd_attach_cpu_data_fd().

<How to test>
1. Execute network(listen) server
 # trace-cmd listen -p 12345

2. Execute network client
 # trace-cmd record -e sched* -N <server IP>:12345

3. Stop the record on client
 ^C

 Here, network server should output a line "CPUX data recorded at offset=XXXX",
 but current network server aborts silently.

 Moreover the client's per-cpu files are separated. (Normally those files
 are merged into one trace file.)

4. Confirm error on network server
 #  dmesg | tail -1
[18551.537113] trace-cmd[23073]: segfault at ffffffffffffffe8 ip 0000000000432fd1 sp 00007fffffa4caa0 error 5 in trace-cmd[400000+47000]

 After we would introduce this patch, the server will be fully able to output
 the client's tracing data and we will not get this error.

Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 trace-output.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/trace-output.c b/trace-output.c
index ed81466..b033baa 100644
--- a/trace-output.c
+++ b/trace-output.c
@@ -1202,6 +1202,7 @@ int tracecmd_attach_cpu_data_fd(int fd, int cpus, char * const *cpu_data_files)
 	handle->pevent = tracecmd_get_pevent(ihandle);
 	pevent_ref(pevent);
 	handle->page_size = tracecmd_page_size(ihandle);
+	list_head_init(&handle->options);
 
 	if (tracecmd_append_cpu_data(handle, cpus, cpu_data_files) >= 0)
 		ret = 0;