New subject: [Bug 416404] Resolver blocks and cannot be aborted (ping)

11 Aug 2008

      https://bugzilla.novell.com/show_bug.cgi?id=416404

           Summary: Resolver blocks and cannot be aborted (ping)
           Product: openSUSE 11.0
           Version: Final
          Platform: Other
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Basesystem
        AssignedTo: bnc-team-screening@forge.provo.novell.com
        ReportedBy: lmb@novell.com
         QAContact: qa@suse.de
          Found By: Development

Created an attachment (id=232808)
 --> (https://bugzilla.novell.com/attachment.cgi?id=232808)
strace -ro from ping

If I call "ping dale.suse.de" on my 11.0 system, tries to lookup the address,
which can take a while. That is annoying, but more annoying is that I cannot
abort the lookup:

ping dale.suse.de
PING dale.suse.de (10.10.2.87) 56(84) bytes of data.
^C^C^C^C^C^C^C^C64 bytes from 10.10.2.87: icmp_seq=1 ttl=62 time=38.0 ms

--- dale.suse.de ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 38.037/38.037/38.037/0.000 ms

As you can see, the system did not respond to the SIGINT immediately; in fact,
this takes >5 seconds!

A direct strace to the console can be aborted immediately:

connect(4, {sa_family=AF_INET, sin_port=htons(53),
sin_addr=inet_addr("192.168.1.1")}, 28) = 0
fcntl64(4, F_GETFL)                     = 0x2 (flags O_RDWR)
fcntl64(4, F_SETFL, O_RDWR|O_NONBLOCK)  = 0
gettimeofday({1218486639, 30936}, NULL) = 0
poll([{fd=4, events=POLLOUT, revents=POLLOUT}], 1, 0) = 1
send(4, "\370\210\1\0\0\1\0\0\0\0\0\0\00287\0012\00210\00210\7in-addr\4"...,
41, MSG_NOSIGNAL) = 41
poll(^C 

If I instruct syslog to log to a file (attached), it exhibits the same
behaviour of being uninterruptible.

It seems that ping blocks SIGINT to terminate cleanly and with printing the
summary stats, but it does so before the possibly time-consuming lookup has
completed. (This is also obvious from the fact that it is impossible to abort
before the first ping packet has been sent.)

I suggest to move the signal trickery to a later point in the code.

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[Bug 416404] New: Resolver blocks and cannot be aborted (ping)

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