Re: ssh_handle_packets blocking issue

[Mikhail Kulinich <tysonite@xxxxxxxxx>]

Hello,

It seems that guys meet an issue which I am observing for a year or more.
During migration to new bug tracker, that original issue (created by me) was
missed.
The latest info I sent to the mailing list concerning it:
{{{
#2  0x080e4138 in ssh_socket_unbuffered_read (s=0x8ca3eb0, buffer=0x8c9e1c8,
len=16)
    at /home/shamanin/libssh_lin/
libssh-0.4.4/libssh/socket.c:200
200       rc = recv(s->fd,buffer, len, 0);
Current language:  auto; currently c
(gdb) up
#3  0x080e430b in ssh_socket_completeread (s=0x8ca3eb0, buffer=0x8c9e1c8,
len=16)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/socket.c:275
275       while((r = ssh_socket_unbuffered_read(s, ((uint8_t*)buffer +
total), toread))) {


 (gdb) bt
#0  0xb776e424 in __kernel_vsyscall ()
#1  0xb770a428 in recv () from /lib/tls/i686/cmov/libpthread.so.0
#2  0x080e4138 in ssh_socket_unbuffered_read (s=0x8ca3eb0, buffer=0x8c9e1c8,
len=16)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/socket.c:200
#3  0x080e430b in ssh_socket_completeread (s=0x8ca3eb0, buffer=0x8c9e1c8,
len=16)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/socket.c:275
#4  0x080e4985 in ssh_socket_wait_for_data (s=0x8ca3eb0, session=0x8ca4c58,
len=16)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/socket.c:405
#5  0x080e1e54 in packet_read2 (session=0x8ca4c58)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/packet.c:94
#6  0x080e2429 in packet_read (session=0x8ca4c58)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/packet.c:401
#7  0x080cdd56 in channel_read (channel=0x8ca9720, dest=0x8cad460, count=1,
is_stderr=0)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/channels.c:1916
#8  0x0809958b in maux::SshDescriptor::read (this=0x8ca46d8, cpBuf=0x8cad460
"", iBufLen=1,
    iFlag=0) at ../SshDescriptor.cc:415
#9  0x08053e57 in autotest::SshAccess::_receive (this=0x8ca46d8,
buffer=@0xb32b10a8)
    at ../SshAccess.cc:177
#10 0x080543ed in autotest::SshAccess::onActivity (this=0x8ca46d8,
pWaiter=0x8ca4298, iFlags=1)
    at ../SshAccess.cc:300
#11 0x08092fd3 in maux::Waiter::onActivity (this=0x8ca4298,
pxDescr=0x8ca46d8, iFlags=1)
    at ../Waiter.cc:915
#12 0x08093b7d in maux::Waiter::dispatchOneEvent (this=0x8ca4298) at
../Waiter.cc:692
#13 0x08094992 in maux::Waiter::doMainLoop (this=0x8ca4298) at
../Waiter.cc:506
#14 0x08096f04 in maux::OwnThread<maux::Waiter>::main (this=0x8ca42f4) at
../Thread.hh:183
#15 0x08091afc in maux::mainThreadFunction (pxThreadStartup=0xb63f972c) at
../Thread.cc:40
#16 0xb770350f in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#17 0xb74f07ee in clone () from /lib/tls/i686/cmov/libc.so.6
(gdb) up
#4  0x080e4985 in ssh_socket_wait_for_data (s=0x8ca3eb0, session=0x8ca4c58,
len=16)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/socket.c:405
405         r = ssh_socket_completeread(session->socket,buf,to_read);
(gdb) up
#5  0x080e1e54 in packet_read2 (session=0x8ca4c58)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/packet.c:94
94            rc = ssh_socket_wait_for_data(session->socket, session,
blocksize);
(gdb) up
#6  0x080e2429 in packet_read (session=0x8ca4c58)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/packet.c:401
401       return packet_read2(session);
(gdb) up
#7  0x080cdd56 in channel_read (channel=0x8ca9720, dest=0x8cad460, count=1,
is_stderr=0)
    at /home/shamanin/libssh_lin/libssh-0.4.4/libssh/channels.c:1916
1916        if ((packet_read(session)) != SSH_OK ||
(gdb) print channel->stdout_buffer
$1 = (ssh_buffer) 0x8ca8640
(gdb) print channel->stdout_buffer->used
$2 = 0
(gdb) print *channel->stdout_buffer
$3 = {
  data = 0x8cacc58 "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<hello
xmlns=\"urn:ietf:params:xml:ns:netconf:base:1.0\">\n<capabilities>\n<capability>urn:ietf:params:netconf:base:1.0</capability>\n<capability>urn:ietf:params:netc"...,
used = 0, allocated = 2048, pos = 0}

}}}

If you need more details I'll try to get them.

2011/4/5 Aris Adamantiadis <aris@xxxxxxxxxxxx>

> Jeetu,
>
> I read your email in details and still am not sure it's correlated with
> Sharon's problem.
> Could you provide me a backtrace (with full symbols if possible) of a
> stuck process (with the -1 timeout) so I can have an idea of what
> condition it's waiting for and why it doesn't arrive.
>
> A verbose log (with ssh_options_set) of the same session would greatly
> help, along with the code snippet you're using to handle ssh connexions.
>
> Thanks,
>
> Aris
>
> Le 5/04/11 14:20, jeetu.golani@xxxxxxxxx a écrit :
> > Hi,
> >
> >> Hello Jeetu, Sharon,
> >
> >> I'll look at that issue asap. It's a blocking problem for release 0.5.
> >
> >> Aris
> >
> > Aris, Thanks so much :) Please let me know if you need me to try
> something
> > or any further data to help you debug this.
> >
> >> If this is on Windows, which Windows version are you running? We have a
> >> poll(2)-emulation for older Windows versions. This version doesn't set
> >> POLLERR, maybe that's causing the problem.
> >>
> >
> > Andreas, I'm seeing this behaviour on Linux (debian testing). Please let
> > me know if you need any further info to debug this or if I can help in
> any way.
> >
> > Thanks so much yet again for a very nice piece of work :)
> >
> > Bye for now
> > Jeetu
> >
> > ebrain.in | Beehive Computing
> > Discover and run software from any device around you.
> >
>
>


-- 
Mikhail