kopia lustrzana https://gitlab.com/sane-project/website
77 wiersze
3.8 KiB
HTML
77 wiersze
3.8 KiB
HTML
<!-- received="Sun Jun 7 19:42:42 1998 PDT" -->
|
|
<!-- sent="Sun, 7 Jun 1998 19:42:41 -0700" -->
|
|
<!-- name="David Mosberger-Tang" -->
|
|
<!-- email="David.Mosberger@acm.org" -->
|
|
<!-- subject="Re: Problems with CANCEL" -->
|
|
<!-- id="199806080242.TAA24452@panda.mostang.com" -->
|
|
<!-- inreplyto="199806071705.TAA00333@Babylon5.wolfsburg.de" -->
|
|
<title>sane-devel: Re: Problems with CANCEL</title>
|
|
<h1>Re: Problems with CANCEL</h1>
|
|
<b>David Mosberger-Tang</b> (<a href="mailto:David.Mosberger@acm.org"><i>David.Mosberger@acm.org</i></a>)<br>
|
|
<i>Sun, 7 Jun 1998 19:42:41 -0700</i>
|
|
<p>
|
|
<ul>
|
|
<li> <b>Messages sorted by:</b> <a href="date.html#68">[ date ]</a><a href="index.html#68">[ thread ]</a><a href="subject.html#68">[ subject ]</a><a href="author.html#68">[ author ]</a>
|
|
<!-- next="start" -->
|
|
<li> <b>Next message:</b> <a href="0069.html">David Mosberger-Tang: "Re: Problems with Scanning !!!"</a>
|
|
<li> <b>Previous message:</b> <a href="0067.html">Ingo Witzky: "Problems with Scanning !!!"</a>
|
|
<li> <b>In reply to:</b> <a href="0066.html">Oliver.Rauch@Wolfsburg.DE: "Re: Problems with CANCEL"</a>
|
|
<!-- nextthread="start" -->
|
|
<li> <b>Next in thread:</b> <a href="0078.html">Oliver.Rauch@Wolfsburg.DE: "Re: Problems with CANCEL"</a>
|
|
<li> <b>Reply:</b> <a href="0078.html">Oliver.Rauch@Wolfsburg.DE: "Re: Problems with CANCEL"</a>
|
|
<!-- reply="end" -->
|
|
</ul>
|
|
<!-- body="start" -->
|
|
<i>>>>>> On Sun, 7 Jun 1998 19:05:08 +0200 (MET DST), <a href="mailto:Oliver.Rauch@Wolfsburg.DE">Oliver.Rauch@Wolfsburg.DE</a> said:</i><br>
|
|
<p>
|
|
<i> >> Not really, but I'm not sure it's a good idea to block all</i><br>
|
|
<i> >> signals. You may want to play around with this part. Indeed,</i><br>
|
|
<i> >> for testing purposes you could not block anything and see whether</i><br>
|
|
<i> >> that helps.</i><br>
|
|
<p>
|
|
Oliver> I will try that, but it is important to block all signals<br>
|
|
Oliver> between scsi-command and scsi-answer, otherwise we may block<br>
|
|
Oliver> the scsi-bus!<br>
|
|
<p>
|
|
Well, the reason the signals are blocked is to avoid a race condition.<br>
|
|
Without blocking the signals, it could happen that:<br>
|
|
<p>
|
|
(1) sanei_scsi.c:issue() gets called<br>
|
|
(2) req->running gets set<br>
|
|
(3) user hits ctrl-C (or something else that causes a signal)<br>
|
|
(4) sane_cancel() gets invoked <br>
|
|
(5) sanei_scsi_req_flush_all() gets called by sane_cancel()<br>
|
|
(6) sanei_scsi_req_flush_all() sees req->running is set and<br>
|
|
now attempts to read() the reply bytes, which of course<br>
|
|
will never happen (because issue() never got to write()<br>
|
|
the request)<br>
|
|
<p>
|
|
Because of this, all signals that could result in sane_cancel() being<br>
|
|
called must be blocked temporarily.<br>
|
|
<p>
|
|
Oliver> Is it possible that it has to do something with<br>
|
|
Oliver> command-queing and the cammand-queue is already full?<br>
|
|
<p>
|
|
I suppose it could be. Does the UMAX backend attempt to send any scsi<br>
|
|
commands during a sane_cancel() call? I thought not.<br>
|
|
<p>
|
|
--david<br>
|
|
<p>
|
|
<pre>
|
|
--
|
|
Source code, list archive, and docs: <a href="http://www.mostang.com/sane/">http://www.mostang.com/sane/</a>
|
|
To unsubscribe: echo unsubscribe sane-devel | mail <a href="mailto:majordomo@mostang.com">majordomo@mostang.com</a>
|
|
</pre>
|
|
<!-- body="end" -->
|
|
<p>
|
|
<ul>
|
|
<!-- next="start" -->
|
|
<li> <b>Next message:</b> <a href="0069.html">David Mosberger-Tang: "Re: Problems with Scanning !!!"</a>
|
|
<li> <b>Previous message:</b> <a href="0067.html">Ingo Witzky: "Problems with Scanning !!!"</a>
|
|
<li> <b>In reply to:</b> <a href="0066.html">Oliver.Rauch@Wolfsburg.DE: "Re: Problems with CANCEL"</a>
|
|
<!-- nextthread="start" -->
|
|
<li> <b>Next in thread:</b> <a href="0078.html">Oliver.Rauch@Wolfsburg.DE: "Re: Problems with CANCEL"</a>
|
|
<li> <b>Reply:</b> <a href="0078.html">Oliver.Rauch@Wolfsburg.DE: "Re: Problems with CANCEL"</a>
|
|
<!-- reply="end" -->
|
|
</ul>
|