[ovs-build] Failed: ovsrobot/ovs#1644 (series_132966 - 4424f77)

[Travis CI]

Build Update for ovsrobot/ovs
-------------------------------------

Build: #1644
Status: Failed

Duration: 56 mins and 11 secs
Commit: 4424f77 (series_132966)
Author: William Tu
Message: fatal-signal: Catch SIGSEGV and print backtrace.

The patch catches the SIGSEGV signal and prints the backtrace
using libunwind at the monitor daemon. This makes debugging easier
when there is no debug symbol package or gdb installed on production
systems.

The patch works when the ovs-vswitchd compiles even without debug symbol
(no -g option), because the object files still have function symbols.
For example:
 |daemon_unix(monitor)|WARN|SIGSEGV detected, backtrace:
 |daemon_unix(monitor)|WARN|0x0000000000482752 <fatal_signal_handler+0x52>
 |daemon_unix(monitor)|WARN|0x00007fb4900734b0 <killpg+0x40>
 |daemon_unix(monitor)|WARN|0x00007fb49013974d <__poll+0x2d>
 |daemon_unix(monitor)|WARN|0x000000000052b348 <time_poll+0x108>
 |daemon_unix(monitor)|WARN|0x00000000005153ec <poll_block+0x8c>
 |daemon_unix(monitor)|WARN|0x000000000058630a <clean_thread_main+0x1aa>
 |daemon_unix(monitor)|WARN|0x00000000004ffd1d <ovsthread_wrapper+0x7d>
 |daemon_unix(monitor)|WARN|0x00007fb490b3b6ba <start_thread+0xca>
 |daemon_unix(monitor)|WARN|0x00007fb49014541d <clone+0x6d>
 |daemon_unix(monitor)|ERR|1 crashes: pid 122849 died, killed \
    (Segmentation fault), core dumped, restarting

However, if the object files' symbols are stripped, then we can only
get init function plus offset value. This is still useful when trying
to see if two bugs have the same root cause, Example:
 |daemon_unix(monitor)|WARN|SIGSEGV detected, backtrace:
 |daemon_unix(monitor)|WARN|0x0000000000482752 <_init+0x7d68a>
 |daemon_unix(monitor)|WARN|0x00007f5f7c8cf4b0 <killpg+0x40>
 |daemon_unix(monitor)|WARN|0x00007f5f7c99574d <__poll+0x2d>
 |daemon_unix(monitor)|WARN|0x000000000052b348 <_init+0x126280>
 |daemon_unix(monitor)|WARN|0x00000000005153ec <_init+0x110324>
 |daemon_unix(monitor)|WARN|0x0000000000407439 <_init+0x2371>
 |daemon_unix(monitor)|WARN|0x00007f5f7c8ba830 <__libc_start_main+0xf0>
 |daemon_unix(monitor)|WARN|0x0000000000408329 <_init+0x3261>
 |daemon_unix(monitor)|ERR|1 crashes: pid 106155 died, killed \
	(Segmentation fault), core dumped, restarting

Most C library functions are not async-signal-safe, meaning that
it is not safe to call them from a signal handler, for example
printf() or fflush(). To be async-signal-safe, the handler only
collects the stack info using libunwind, which is signal-safe, and
issues 'write' to the pipe, where the monitor thread reads and
prints to ovs-vswitchd.log.

Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/590503433
Signed-off-by: William Tu <u9012063 at gmail.com>
Signed-off-by: 0-day Robot <robot at bytheb.org>

View the changeset: https://github.com/ovsrobot/ovs/compare/1ca0323e7c29^...4424f7755915

View the full build log and details: https://travis-ci.org/ovsrobot/ovs/builds/590569122?utm_medium=notification&utm_source=email

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