On Mon, Jan 08, 2018 at 03:34:57PM +0100, Jiri Olsa wrote: > On Mon, Jan 08, 2018 at 11:05:12AM +0800, Du, Changbin wrote: > > Hi Olsa, > > What about this fix now? Thanks! > > > > On Tue, Dec 26, 2017 at 05:26:56PM +0800, changbin...@intel.com wrote: > > > From: Changbin Du <changbin...@intel.com> > > > > > > The terminal character '\0' should take into account as size of the string > > > buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and > > > '--trace-funcs' options didn't work as expected when the <func> doesn't > > > exist. > > > > > > I didn't dive into kernel ftrace fops, but strace shows that if usersapce > > > writes a non-terminated string, the kernel side will return success but > > > no filter applied. After this fix in userspace, the kernel will return an > > > error. > > > > > > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg > > > 0) 0.140 us | rcu_all_qs(); > > > 3) 0.304 us | mutex_unlock(); > > > 0) 0.153 us | find_vma(); > > > 3) 0.088 us | __fsnotify_parent(); > > > 0) 6.145 us | handle_mm_fault(); > > > 3) 0.089 us | fsnotify(); > > > 3) 0.161 us | __sb_end_write(); > > > 3) 0.710 us | SyS_close(); > > > 3) 7.848 us | exit_to_usermode_loop(); > > > > > > On above example, I specified function filter 'abcdefg' but all functions > > > are enabled. > > hum, haven't checked, but looks like the filter is not working at all now: > > [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs > proc_sys_read > write ' ' to tracing/set_ftrace_pid failed: Invalid argument > [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs SyS_read > write ' ' to tracing/set_ftrace_pid failed: Invalid argument > [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs fsnotify > write ' ' to tracing/set_ftrace_pid failed: Invalid argument > Thanks for your test. I forgot to test normal case and thought the err is expected...
This time I dived into kernel side, and found 3 issues (if I am all right) at the kernel function trace_get_user(). This function has problems to process both complete C string or not. I will send the kernel patches and Cc you guys. And I still think it is better let perf write a complete C string. Thanks! Changbin Du > jirka > [...]
