[Serusers] Problems with locking in timer routine

Thu May 29 00:10:37 CEST 2003

Maxim,

do you experience the same problem without your extensions ? Are you able
to reproduce it ? Could you try a CVS snapshot ?

I have never seen such a problem, could you send me some description if
there is any way to reproduce it ?

  Jan.

On 29-05 00:44, Maxim Sobolev wrote:
> Hi folks,
> 
> I am having problems with locking in timer routine (ser 0.8.10), 
> particularly with the my recent addition to the nathelper - udp pinger. 
> This piece of code is being invoked periodically by the timer, retrieves 
> list of all currently registered contacts and sends short udp message to 
> each of them. Obviously, routine which retrieves all contacts locks each 
> domain before accessing it, but apparently it doesn't work as expected.
> 
> Following is the dump of debugging session:
> 
> -bash-2.05b$ sudo gdb ~/PortaSIP/ser/work/ser-0.8.10/ser ser.core
> GNU gdb 4.18 (FreeBSD)
> Copyright 1998 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain 
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "i386-unknown-freebsd"...Deprecated bfd_read 
> called at 
> /usr/src/gnu/usr.bin/binutils/gdb/../../../../contrib/gdb/gdb/dbxread.c 
> line 2627 in elfstab_build_psymtabs
> Deprecated bfd_read called at 
> /usr/src/gnu/usr.bin/binutils/gdb/../../../../contrib/gdb/gdb/dbxread.c 
> line 933 in fill_symbuf
> 
> Core was generated by `ser'.
> Program terminated with signal 11, Segmentation fault.
> Reading symbols from /usr/lib/libc.so.4...done.
> Reading symbols from /usr/local/lib/ser/modules/sl.so...done.
> Reading symbols from /usr/local/lib/ser/modules/tm.so...done.
> Reading symbols from /usr/local/lib/ser/modules/rr.so...done.
> Reading symbols from /usr/local/lib/ser/modules/maxfwd.so...done.
> Reading symbols from /usr/local/lib/ser/modules/usrloc.so...done.
> Reading symbols from /usr/local/lib/ser/modules/registrar.so...done.
> Reading symbols from /usr/local/lib/ser/modules/nathelper.so...done.
> Reading symbols from /usr/local/lib/ser/modules/textops.so...done.
> Reading symbols from /usr/local/lib/ser/modules/radius_auth.so...done.
> Reading symbols from /usr/local/lib/libradiusclient.so.0...done.
> Reading symbols from /usr/lib/libmd.so.2...done.
> Reading symbols from /usr/lib/libcrypt.so.2...done.
> Reading symbols from /usr/libexec/ld-elf.so.1...done.
> #0  0x2a1a62df in get_all_ucontacts (buf=0x80d5248, len=1402) at dlist.c:110
> 110                                     if (c->c.len <= 0)
> (gdb) bt
> #0  0x2a1a62df in get_all_ucontacts (buf=0x80d5248, len=1402) at dlist.c:110
> #1  0x2a1c4b3e in _init () from /usr/local/lib/ser/modules/nathelper.so
> #2  0x8073679 in timer_ticker () at timer.c:118
> #3  0x805e912 in main_loop () at main.c:654
> #4  0x80611a1 in main (argc=1, argv=0xbfbffdb8) at main.c:1383
> #5  0x804c5a6 in _start ()
> (gdb) print c
> $1 = (ucontact_t *) 0x460a0d30
> (gdb) print *c
> Cannot access memory at address 0x460a0d30.
> (gdb) print *r
> $2 = {domain = 0x282ec0d8, aor = {s = 0x282f4638 "011801", len = 6}, 
> contacts = 0x282f5cb8, slot = 0x282ed418, d_ll = {
>     prev = 0x282ef0d8, next = 0x0}, s_ll = {prev = 0x0, next = 0x0}}
> (gdb) print *r->contacts
> $3 = {domain = 0x7a3d6863, aor = 0x34476839, c = {s = 0x37364b62 
> <Address 0x37364b62 out of bounds>, len = 959328819},
>   expires = 825243494, q = 2.12359957e+20, callid = {s = 0x32663238 
> <Address 0x32663238 out of bounds>, len = 1714774885},
>   cseq = 1631019574, state = 1631020084, user_agent = {s = 0x62386438 
> <Address 0x62386438 out of bounds>, len = 775107636},
>   next = 0x460a0d30, prev = 0x3a6d6f72}
> (gdb) print *r->contacts->next
> Cannot access memory at address 0x460a0d30.
> (gdb) l 100
> 95              void *cp;
> 96              int shortage;
> 97
> 98              cp = buf;
> 99              shortage = 0;
> 100             /* Reserve space for terminating 0000 */
> 101             len -= sizeof(c->c.len);
> 102             for (p = root; p != NULL; p = p->next) {
> 103                     lock_udomain(p->d);
> 104                     if (p->d->d_ll.n <= 0) {
> (gdb) l
> 105                             unlock_udomain(p->d);
> 106                             continue;
> 107                     }
> 108                     for (r = p->d->d_ll.first; r != NULL; r = 
> r->d_ll.next) {
> 109                             for (c = r->contacts; c != NULL; c = 
> c->next) {
> 110                                     if (c->c.len <= 0)
> 111                                             continue;
> 112                                     if (len >= 
> (int)(sizeof(c->c.len) + c->c.len)) {
> 113                                             memcpy(cp, &c->c.len, 
> sizeof(c->c.len));
> 114                                             cp += sizeof(c->c.len);
> 
> As you can see, we are locked domain in question (line 103), but still, 
> found one of records to be in the inconsistent state (contacts aren't 
> initialized).
> 
> Does anyone have any ideas about what could be wrong with this? I an 
> seeing similar problem in the code that periodically expires contacts.
> 
> -Maxim
> 
> 
> _______________________________________________
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> serusers at lists.iptel.org
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