[sane-devel] [RFC] Locking devices via sanei_access lib...

[Johannes Meixner]

Hello,

On Feb 7 12:11 Gerhard Jaeger wrote (shortened):
> The idea is to provide a simple locking mechanism for the backends,
> to have exclusive access to one scanner during an operation:
... 
> What do you guys think of this lib - is it useful? 

I even think exclusive access should be used by default
because I think normally it doesn't make sense when there
is more than one process which talks to the same scanner
(i.e. "the same scanner" but not "the same backend" because
one backend can drive several scanners).

Once it happened while I did a nice (you may say stupid) stress test

for i in $( seq 100 )
do sane-find-scanner & scanimage -L &
done

that one of my USB scanners made funny noise: It seems it tried
to move its scanning unit beyond its physical limits.
I have no idea how this could have happened but I guess the scanner
was simply totally confused by the multiple concurrent accesses.

By the way:
The reason for the above stress-test was that this way I could
stop the kernel (no single error message in the logs  - just a
sudden stop) - meanwhile I do no longer use the crap SCSI
host adapter ;-)


Kind Regards,
Johannes Meixner
-- 
SUSE LINUX Products GmbH, Maxfeldstrasse 5      Mail: jsmeix@suse.de
90409 Nuernberg, Germany                    WWW: http://www.suse.de/