[libvirt] [PATCH] virlog: Add stack trace log when libvirt receives fatal signal

[Wangrui (K)]

> -----Original Message-----
> From: Daniel P. Berrange [mailto:berrange at redhat.com]
> Sent: Tuesday, May 20, 2014 5:05 PM
> To: Wangrui (K)
> Cc: libvir-list at redhat.com; zhouyimin Zhou(Yimin); Yanqiangjun
> Subject: Re: [PATCH] virlog: Add stack trace log when libvirt receives fatal signal
> 
> On Tue, May 20, 2014 at 08:59:37AM +0000, Wangrui (K) wrote:
> > An earlier commit(c0c8c1) Dan removed global log buffer feature entirely
> > because of duplicate log messages. An improvement is introduced. That is
> > dumping stack trace instead of log buffer upon libvirt crash.
> 
> 
> This is not going to work. virLogStackTraceToFd invokes the
> backtrace/backtrace_symbols_fd functions which are not async
> signal safe. They are also not likely to be reliable to use
> when you have memory corruption triggering the signal.
> 
> The 'abrt' program is commonly used on modern Linux distros to
> generate stack traces when processes crash / terminate abnormally.
> abrt has the added benefit that the stack traces it records include
> all function parameters and local variables.
> 

Oops.
I didn't realize Async-signal-(un)safe functions in virLogStackTraceToFd.
And it seems that only kernel coredump can be used in this case.
My original purpose is to trace stack on crash/obort and etc without
using kernel.core_pattern (sometimes kernel coredump is not turned on ).

Thanks.

> Regards,
> Daniel
> --
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