Re: [libvirt] 答复: [PATCH] security: Use VIR_DEBUG instead of VIR_INFO in virSecurityDACSetOwnershipInternal

First: all of those backtrace is our private libvirt version backtrace. I find opensource also have this problem 1、backtrace of child

(gdb) bt #0 __lll_lock_wait_private () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:95 #1 0x00007fcd26f7299c in _L_lock_2462 () at tzset.c:621 #2 0x00007fcd26f727d7 in __tz_convert (timer=0x7fcd2727fec0 <tzset_lock>, timer@entry=0x7fcd1a694068, use_localtime=use_localtime@entry=0, tp=tp@entry=0x7fcd1a694070) at tzset.c:624 #3 0x00007fcd26f7075a in __GI___gmtime_r (t=t@entry=0x7fcd1a694068, tp=tp@entry=0x7fcd1a694070) at gmtime.c:28 #4 0x00007fcd2a06b41d in virTimeLocalOffsetFromUTC (offset=offset@entry=0x7fcd1a6940e0) at util/virtime.c:385 #5 0x00007fcd2a06b560 in virTimeStringNowRaw (buf=buf@entry=0x7fcd1a6941a0 "\023") at util/virtime.c:222

#6 0x00007fcd2a034e7e in virLogVMessage (source=<optimized out>, priority=VIR_LOG_INFO, filename=0x7fcd2a28c04a "security/security_dac.c", linenr=556, funcname=0x7fcd2a28c940 <__func__.22722> "virSecurityDACSetOwnershipInternal", metadata=0x0, fmt=fmt@entry=0x7fcd2a28c2f8 "Setting DAC user and group on '%s' to '%ld:%ld'", vargs=vargs@entry=0x7fcd1a694220) at util/virlog.c:585 #7 0x00007fcd2a035427 in virLogMessage (source=source@entry=0x7fcd2a519d90 <virLogSelf>, priority=priority@entry=VIR_LOG_INFO, filename=filename@entry=0x7fcd2a28c04a "security/security_dac.c", linenr=linenr@entry=556, funcname=funcname@entry=0x7fcd2a28c940 <__func__.22722> "virSecurityDACSetOwnershipInternal", metadata=metadata@entry=0x0, fmt=fmt@entry=0x7fcd2a28c2f8 "Setting DAC user and group on '%s' to '%ld:%ld'") at util/virlog.c:515

We can see in libvirtd 16th thread, it wait a message from child process. But child process is deadlocked at virTimeLocalOffsetFromUTC point.

If we use VIR_DEBUG, and our loglevel is info, then VIR_DEBUG will not call virTimeLocalOffsetFromUTC, then avoid deadlock.