[lttng-dev] epoll_wait reboot kernel?

[Mathieu Desnoyers]

Hi Zhenyu,

Which gcc version do you use ?

(gcc --version)

Thanks,

Mathieu

----- Original Message -----
> From: "zhenyu.ren" <zhenyu.ren at aliyun.com>
> To: "lttng-dev" <lttng-dev at lists.lttng.org>, "zhenyu.ren" <zhenyu.ren at aliyun.com>
> Sent: Monday, February 24, 2014 4:36:36 AM
> Subject: Re: [lttng-dev] epoll_wait reboot kernel?
> 
> Oh,It seems not epoll related . I am using DBG/ERR() as debug way ,but this
> print-style method doesn't work as expected,so I mistake for epoll_wait.
> It seems gcc problem because if  I changed lib_ring_buffer_do_copy as the
> following,all  work well
> 
> #define lib_ring_buffer_do_copy(config, dest, src, len)         \
> do {                                                            \
>         size_t __len1 = (len);                                  \
>         /*here , not __len=(len)*/
> mdelay(0x135);\
>         if (__builtin_constant_p(len))                          \
>                 memcpy(dest, src, __len1);                      \
>         else                                                    \
>                 inline_memcpy(dest, src, __len1);               \
> } while (0)
> 
> I disasembled lib_ring_buffer_write() and "vimdiff bad good" shows :
> 49c:       48 89 da                mov    %rbx,%rdx
> |       49c:
> 4c 89 f2                mov    %r14,%rdx
> 
> here rdx is the 3rd parameter to inline_memcpy().
> 
> Thanks
> zhenyu.ren
> 
> 
> >Hi,lttng-dev
> >
>  >  I am working on rhel6(2.6.32.220) and ust is working very well.But when I
>  >  use lttng-modules (after "lttng start"),the kernel reboots immediately
>  >  >without any message output to console.
> >
> >  It took me some days finding out what results in reboot. I shortcut
> >  __event_probe__##_name() before _tstruct but kernel still reboot(So what
> >  left is  >metadata_printf).If I comment out "mask |= POLLIN" in
> >  lttng_metadata_ring_buffer_poll() ,kernel do not reboot. What I find out
> >  is before reboot the >callchain of  lttng-consumerd thread is
> >  consumer_thread_metadata_poll()->lttng_poll_wait(wait for metadata
> >  stream)->compat_epoll_wait().
> >
> > I want to use poll instead as epoll in lttng-tools ,I changed lttng-tools
> > configure file to not use epoll(undef HAVE_EPOLL),but "lttng enable-event
> > -a -k >"failed :(Do I miss anything?)
> >#lttng enable-event -a -k
> >DEBUG1 [17837/18080]: Wait for client response (in thread_manage_clients()
> >at main.c:3709)
> >DEBUG1 [17837/18080]: Receiving data from client ... (in
> >thread_manage_clients() at main.c:3754)
> >DEBUG1 [17837/18080]: Nothing recv() from client... continuing (in
> >thread_manage_clients() at main.c:3758)
> >DEBUG1 [17837/18080]: Clean command context structure (in
> >clean_command_ctx() at main.c:535)
> >DEBUG1 [17837/18080]: Accepting client command ... (in
> >thread_manage_clients() at main.c:3667)
> >DEBUG1 [17837/18080]: Wait for client response (in thread_manage_clients()
> >at main.c:3709)
> >DEBUG1 [17837/18080]: Receiving data from client ... (in
> >thread_manage_clients() at main.c:3754)
> >DEBUG1 [17837/18080]: Processing client command 7 (in process_client_msg()
> >at main.c:2579)
> >DEBUG1 [17837/18080]: Getting session k-test by name (in
> >process_client_msg() at main.c:2656)
> >DEBUG1 [17837/18080]: Creating kernel session (in create_kernel_session() at
> >main.c:2495)
> >DEBUG3 [17837/18080]: Created hashtable size 4 at 0x669410 of type 1 (in
> >lttng_ht_new() at hashtable.c:112)
> >DEBUG1 [17837/18080]: Kernel session created (fd: 21) (in
> >kernel_create_session() at kernel.c:109)
> >DEBUG3 [17837/18080]: Copying tracing session consumer output in kernel
> >session (in copy_session_consumer() at main.c:2393)
> >DEBUG3 [17837/18080]: Created hashtable size 4 at 0x66a750 of type 1 (in
> >lttng_ht_new() at hashtable.c:112)
> >DEBUG3 [17837/18080]: Copy session consumer subdir /kernel (in
> >copy_session_consumer() at main.c:2428)
> >DEBUG3 [17837/18080]: mkdir() recursive
> >/root/lttng-traces/k-test-20140222-131335 with mode 504 for uid 0 and gid 0
> >(in run_as_mkdir_recursive() at >runas.c:310)
> >DEBUG1 [17837/18080]: Using run_as_clone (in run_as() at runas.c:293)
> >lttng-sessiond: ht-cleanup.c:92: thread_ht_cleanup: Assertion `pollfd ==
> >ht_cleanup_pipe[0]' failed.
> >
> >  It seems lttng-tools  in ubuntu 12.04 is using poll,isnt it?
> >
>  > Does anyone have any suggestions to me ?
> 
> >PS:.lttng(ust/module/tool) version is 2.3.0 and urcu version is 0.8
> 
> 
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> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com