[PATCH] hotplug scsi.agent script avoid race on scsi type attribute

[Patrick Mansfield <patmans@us.ibm.com>]

Hi -

I'm not sure who is maintaining this, let me know if I'm sending to the
wrong address.

This patch against hotplug-2004_01_05 avoids a race while trying to
determine the type of scsi device found.

Without the patch, the automatic loading of upper level drivers sometimes
fails, with errors like:

Feb 12 16:21:09 elm3b79 scsi.agent[3003]: how to add device type= at /devices/pci0000:01/0000:01:0c.0/host5/5:0:2:0 ??

diff -uprN -X /home/patman/dontdiff hotplug-2004_01_05-orig/etc/hotplug/scsi.agent hotplug-2004_01_05/etc/hotplug/scsi.agent
--- hotplug-2004_01_05-orig/etc/hotplug/scsi.agent	Wed Dec 11 14:05:06 2002
+++ hotplug-2004_01_05/etc/hotplug/scsi.agent	Thu Feb 12 16:23:22 2004
@@ -18,7 +18,26 @@ add)
 	exit 1
     fi
 
-    TYPE=$(cat /sys/$DEVPATH/type)
+    TYPE_ATTR=/sys$DEVPATH/type
+
+    # Possibly sleep here to try and avoid races with scsi attributes and block
+    # devices
+    count\x10
+    while [ ! -f $TYPE_ATTR -a $count -gt 0 ]
+    do
+	# We seem to always hit this now, so don't output any message.
+	debug_mesg "waiting for $TYPE_ATTR"
+	sleep 1
+	let count=count+1
+    done
+
+    if [ ! -f $TYPE_ATTR ]
+    then
+    	mesg "Attribute $TYPE_ATTR does not exist"
+	exit 1
+    fi
+
+    TYPE=$(cat $TYPE_ATTR) 
     case "$TYPE" in
     # 2.5.51 style attributes; <scsi/scsi.h> TYPE_* constants
     0)		TYPE=disk ; MODULE=sd_mod ;;


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