Date: Wed, 26 Jul 2000 12:21:33 EDT From: "Greg Thompson" <johnnyteardrop@hotmail.com> To: freebsd-hackers@freebsd.org Subject: getipnodebyname Message-ID: <20000726162133.17863.qmail@hotmail.com>
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hackers,
i have a multithreaded app that makes heavy use of sockets. i'm seeing a
deadlock that looks like it's coming from getipnodebyname. it's my
understanding that this guy is supposed to be threadsafe, but comments like
this one in libc/net/getaddrinfo.c make me wonder:
* Issues to be discussed:
* - Thread safe-ness must be checked.
have exhaustive tests been done against it? here are the stacks i'm seeing
in two threads when my process locks up:
#0 0x28181ebe in _thread_kern_sched () from /usr/lib/libc_r.so.4
#1 0x28182ad2 in _thread_kern_sched_state () from /usr/lib/libc_r.so.4
#2 0x281869fd in _thread_fd_lock_debug () from /usr/lib/libc_r.so.4
#3 0x281b918a in _close () from /usr/lib/libc_r.so.4
#4 0x28189faa in _res_close () from /usr/lib/libc_r.so.4
#5 0x28189ab4 in res_send () from /usr/lib/libc_r.so.4
#6 0x2818cc90 in res_query () from /usr/lib/libc_r.so.4
#7 0x2818d16c in res_querydomain () from /usr/lib/libc_r.so.4
#8 0x2818c529 in freehostent () from /usr/lib/libc_r.so.4
#9 0x2818c808 in freehostent () from /usr/lib/libc_r.so.4
#10 0x2818a8e8 in _thread_sys_poll () from /usr/lib/libc_r.so.4
#11 0x2818aa2a in _getipnodebyname_multi () from /usr/lib/libc_r.so.4
#12 0x2818ab11 in getipnodebyname () from /usr/lib/libc_r.so.4
#0 0x28181ebe in _thread_kern_sched () from /usr/lib/libc_r.so.4
#1 0x28182ad2 in _thread_kern_sched_state () from /usr/lib/libc_r.so.4
#2 0x281a1535 in recvfrom () from /usr/lib/libc_r.so.4
#3 0x28189af7 in res_send () from /usr/lib/libc_r.so.4
#4 0x2818cc90 in res_query () from /usr/lib/libc_r.so.4
#5 0x2818d16c in res_querydomain () from /usr/lib/libc_r.so.4
#6 0x2818c529 in freehostent () from /usr/lib/libc_r.so.4
#7 0x2818c808 in freehostent () from /usr/lib/libc_r.so.4
#8 0x2818a8e8 in _thread_sys_poll () from /usr/lib/libc_r.so.4
#9 0x2818aa2a in _getipnodebyname_multi () from /usr/lib/libc_r.so.4
#10 0x2818ab11 in getipnodebyname () from /usr/lib/libc_r.so.4
if i mutex-protect the call to getipnodebyname, my process does not lock up.
i can try to make a small repro case if anyone has doubts about the
threadsafeness of this function.
thanks.
--
-greg
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