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Re: [libvirt] [PATCH 1/2] Avoid taking lock in libvirt debug dump

On 03/17/2011 01:41 AM, Daniel Veillard wrote:
> As pointed out, locking the buffer from the signal handler
> cannot been garanteed to be safe, so to avoid any hazard


> we prefer the trade off of dumping logs possibly messed up
> by concurrent logging activity rather than risk a daemon
> crash.
> * src/util/logging.c: change virLogEmergencyDumpAll() to not
>   take any lock on the log buffer but reset buffer content variables
> +    /*

> +     * Since we can't lock the buffer safely from a signal handler
> +     * we mark it as empty in case of concurrent access, and proceed
> +     * with the data, at worse we will output something a bit weird
> +     * if another thread start logging messages at the same time.
> +     * Note that virLogStr() uses virLogEnd for the computations and
> +     * writes to the buffer and then only update virLogLen and virLogStart

s/then only update/only then updates/

ACK with those nits fixed.

Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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