From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Williams <steve@icarus.com>
Date: Wed, 23 May 2001 00:44:45 +0000
Subject: Re: Hotunplug
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--==_Exmh_407786057430
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I've made a go at implementing support for hot unplug in the hotplug
scripts. What I have done is calculated a path to a "remover" program
that is passed as the REMOVE environment variable to the existing add
scripts. If the add script wants to make something happen when the
device is removed, it writes something to the remover and marks it
executable.

The hotplug scripts' response to this is to run the remover when the
device is pulled. So this is the hotplug script for my device.  It is
called on add, and creates a remover to remove the symbolic link, like
so:

  case "$PRODUCT" in

  547/2235/*)
    exec /usr/sbin/gflashd -I /usr/share/gflash/aa55.ihx ;;

  12c5/*/*) 
    echo 'rm -f /var/run/gflash.lnk' > $REMOVER
    chmod u+x $REMOVER
    exec /usr/sbin/gflashd -m 0666 -L/var/run/gflash.lnk ;;

  esac

(The first case is loading the firmware, so a renumeration is about to
happen and the link is not ready to be created.)

I tested it on my system, and the good news is this that remove is very
fast. I pull the device and the /var/run/gflash.lnk goes away right away.
This is *exactly* what I want.

So I've attached a patch to the CVS version , for your critical review.
It's surprisingly small.

-- 
Steve Williams                "The woods are lovely, dark and deep.
steve@icarus.com              But I have promises to keep,
steve@picturel.com            and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."


--==_Exmh_407786057430
Content-Type: application/x-patch ; name="usb-remove.patch"
Content-Description: usb-remove.patch
Content-Disposition: attachment; filename="usb-remove.patch"

Index: etc/hotplug/usb.agent
===================================================================
RCS file: /cvsroot/linux-hotplug/admin/etc/hotplug/usb.agent,v
retrieving revision 1.12
diff -u -r1.12 usb.agent
--- etc/hotplug/usb.agent	2001/04/24 15:07:33	1.12
+++ etc/hotplug/usb.agent	2001/05/23 00:35:47
@@ -18,6 +18,14 @@
 #	DEVFS=/proc/bus/usb
 #	DEVICE=/proc/bus/usb/%03d/%03d
 #
+# This script then adds the variable:
+#
+#       REMOVER=/var/run/usb/<some string unique to $DEVICE>
+#
+# This is the path where the script would like to find a remover, if
+# the target device needs one. This script is executed on remove if
+# it is executable when the remove happens.
+#
 # If usbdevfs is mounted on /proc/bus/usb, $DEVICE is a file which
 # can be read to get the device's current configuration descriptor.
 # (The "usbmodules" utility helps do that.)
@@ -269,6 +277,11 @@
     done
 }
 
+#
+# declare a REMOVER name that the add action can use to create a
+# remover, or that the remove action can use to execute a remover.
+#
+declare -rx REMOVER=/var/run/usb/`echo $DEVICE | sed -e 's;/;%;g'`
 
 #
 # What to do with this USB hotplug event?
@@ -281,6 +294,10 @@
     FOUND=false
     LABEL="USB product $PRODUCT"
 
+    if [ -e "$REMOVER" ]; then
+	rm -f "$REMOVER"
+    fi
+
     # on 2.4 systems, modutils 2.4.2+ maintains MAP_CURRENT
     # ... otherwise we can't rely on it (sigh)
     case "$KERNEL" in
@@ -320,6 +337,13 @@
 	exit 2
     fi
 
+    ;;
+
+remove)
+    if [ -x $REMOVER ]; then
+	$REMOVER
+    fi
+    rm -f $REMOVER
     ;;
 
 *)
Index: etc/hotplug/usb.rc
===================================================================
RCS file: /cvsroot/linux-hotplug/admin/etc/hotplug/usb.rc,v
retrieving revision 1.8
diff -u -r1.8 usb.rc
--- etc/hotplug/usb.rc	2001/03/22 04:52:56	1.8
+++ etc/hotplug/usb.rc	2001/05/23 00:35:47
@@ -134,6 +134,11 @@
 	return 1
     fi
 
+    # Create a directory to hold remover programs. Close it up so
+    # that only hotplug scripts can write to this directory.
+    mkdir /var/run/usb
+    chmod 0700 /var/run/usb
+
     # hotplug events didn't fire during booting;
     # cope with devices that enumerated earlier
     # and may not have been fully configured.

--==_Exmh_407786057430--



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