[libvirt] libvirtd (from git) no longer responds to 'kill'

[Daniel P. Berrange]

On Mon, Feb 11, 2013 at 02:02:21PM +0000, Richard W.M. Jones wrote:
> 
> This seems to be some sort of deadlock, easily reproduced by running
> the libguestfs test suite, or even just 'libguestfs-test-tool'.
> 
> Here is a stack trace:
> 
> (gdb) t a a bt

> Thread 8 (Thread 0x7fe64edd4700 (LWP 20024)):
> #0  __lll_lock_wait ()
>     at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
> ---Type <return> to continue, or q <return> to quit---
> #1  0x000000328ca09ca6 in _L_lock_836 () from /lib64/libpthread.so.0
> #2  0x000000328ca09ba8 in __GI___pthread_mutex_lock (
>     mutex=mutex at entry=0x7fe64006eb30) at pthread_mutex_lock.c:64
> #3  0x00007fe650ad142d in virMutexLock (m=m at entry=0x7fe64006eb30)
>     at util/virthreadpthread.c:85
> #4  0x00007fe650ac38de in virObjectLock (anyobj=anyobj at entry=0x7fe64006eb20)
>     at util/virobject.c:322
> #5  0x00007fe650ce65b1 in virSecurityManagerGetModel (
>     mgr=mgr at entry=0x7fe64006eb20) at security/security_manager.c:236
> #6  0x00007fe650ce994c in virSecuritySELinuxSecurityVerify (
>     mgr=0x7fe64006eb20, def=<optimized out>)
>     at security/security_selinux.c:1806
> #7  0x00007fe650ce7251 in virSecurityManagerVerify (mgr=0x7fe64006eb20, 
>     def=def at entry=0x7fe63400ac20) at security/security_manager.c:573
> #8  0x00007fe650ce3cd4 in virSecurityStackVerify (mgr=<optimized out>, 
>     def=0x7fe63400ac20) at security/security_stack.c:125
> #9  0x00007fe650ce7251 in virSecurityManagerVerify (mgr=0x7fe64001cc50, 
>     def=def at entry=0x7fe63400ac20) at security/security_manager.c:573

This shows the problem - the security driver implementations are not
allowed to call back out to other virSecurityManagerXXX APis like
virSecurityManagerGetModel, since that causes recursive mutex acquisition.
I've cc'd you on a fix

Daniel
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