linux-kernel - RE: perf probe -L sys_select or sys

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Date:	Tue, 11 Aug 2015 22:59:32 +0000
From:	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>
To:	"'Arnaldo Carvalho de Melo'" <acme@...nel.org>
CC:	David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...hat.com>,
	"Namhyung Kim" <namhyung@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: RE: perf probe -L sys_select or sys_poll

Hi Arnaldo,

> From: Arnaldo Carvalho de Melo [mailto:acme@...nel.org]
> 
> Hi Masami,
> 
> 	Have you noticed that sys_select or sys_poll stops after the
> first few lines? Please let me know if you need more info than is below.

OK, I'll see what is going.

> 
>   [root@zoo ~]# perf probe -L sys_select
>   <SyS_select@...me/git/linux/fs/select.c:0>
>       0  SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
>                         fd_set __user *, exp, struct timeval __user *, tvp)
>          {
>                 struct timespec end_time, *to = NULL;
> 
>   [root@zoo ~]# perf probe -L sys_poll
>   <SyS_poll@...me/git/linux/fs/select.c:0>
>       0  SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
>                         int, timeout_msecs)
>          {
>                 struct timespec end_time, *to = NULL;
> 
>   [root@zoo ~]#
> 
> I haven't investigated it too much, if there is some trouble that makes
> 'perf probe -L' to stop like that maybe we should warn the user somehow?

It seems a bug of -L, since it works correctly with fs/select.c:957.

$ ./perf probe -L fs/select.c:957
</home/mhiramat/ksrc/linux-3/fs/select.c:957>
    957  SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds$
                        int, timeout_msecs)
         {
    960         struct timespec end_time, *to = NULL;
                int ret;

    963         if (timeout_msecs >= 0) {
    964                 to = &end_time;
    965                 poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SE$
    966                         NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC))$
                }

    969         ret = do_sys_poll(ufds, nfds, to);

    971         if (ret == -EINTR) {
                        struct restart_block *restart_block;

So, something goes wrong when processing syscall functions.

Thanks!



-- 
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu.pt@...achi.com
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