From: Neil Horman <nhorman@redhat.com>
Subject: [RHEL 5.1 PATCH] cciss: ignore results from unsent commands on kexec boot
Date: Fri, 11 May 2007 11:02:40 -0400
Bugzilla: 239520
Message-Id: <20070511150240.GD13296@hmsendeavour.rdu.redhat.com>
Changelog: [scsi] cciss: ignore results from unsent commands on kexec boot


Hey-
	cciss systems can oops on systems during a kexec because they try to
honor results sent back from the device for commands that were issued prior to
the kexec reboot.  This patch is a backport of upstream commit:
7e96287ddc4f42081e18248b6167041c0908004c
Plus the extra code needed in cciss to ignore results from unsent commands
during a kexec reboot.  Tested and confirmed to fix bz 239520

Thanks & Regards
Neil


--- linux-2.6.18.noarch/include/linux/init.h.orig	2007-05-10 07:56:14.000000000 -0400
+++ linux-2.6.18.noarch/include/linux/init.h	2007-05-10 08:41:10.000000000 -0400
@@ -76,6 +76,7 @@
 
 /* Defined in init/main.c */
 extern char saved_command_line[];
+extern unsigned int reset_devices;
 
 /* used by init/main.c */
 extern void setup_arch(char **);
--- linux-2.6.18.noarch/init/main.c.orig	2007-05-10 07:56:14.000000000 -0400
+++ linux-2.6.18.noarch/init/main.c	2007-05-10 08:41:10.000000000 -0400
@@ -128,6 +128,18 @@
 static unsigned int max_cpus = NR_CPUS;
 
 /*
+ * If set, this is an indication to the drivers that reset the underlying
+ * device before going ahead with the initialization otherwise driver might
+ * rely on the BIOS and skip the reset operation.
+ *
+ * This is useful if kernel is booting in an unreliable environment.
+ * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
+ * skipped and devices will be in unknown state.
+ */
+unsigned int reset_devices;
+EXPORT_SYMBOL(reset_devices);
+
+/*
  * Setup routine for controlling SMP activation
  *
  * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
@@ -153,6 +165,14 @@
 
 __setup("maxcpus=", maxcpus);
 
+static int __init set_reset_devices(char *str)
+{
+	reset_devices = 1;
+	return 1;
+}
+
+__setup("reset_devices", set_reset_devices);
+
 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 static const char *panic_later, *panic_param;
--- linux-2.6.18.noarch/Documentation/kernel-parameters.txt.orig	2007-05-10 07:56:08.000000000 -0400
+++ linux-2.6.18.noarch/Documentation/kernel-parameters.txt	2007-05-10 08:41:09.000000000 -0400
@@ -1367,6 +1367,9 @@
 
 	reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area
 
+	reset_devices	[KNL] Force drivers to reset the underlying device
+			during initialization.
+
 	resume=		[SWSUSP]
 			Specify the partition device for software suspend
 
--- linux-2.6.18.noarch/drivers/block/cciss.c.orig	2007-05-10 08:01:50.000000000 -0400
+++ linux-2.6.18.noarch/drivers/block/cciss.c	2007-05-10 08:40:59.000000000 -0400
@@ -2074,6 +2074,13 @@
 		       ctlr, complete);
 		/* not much we can do. */
 #ifdef CONFIG_CISS_SCSI_TAPE
+		/* We might get notification of completion of commands
+		 * which we never issued in this kernel if this boot is
+		 * taking place after previous kernel's crash. Simply
+		 * ignore the commands in this case.
+		 */
+		if (reset_devices)
+			return 0;
 		return 1;
 	}
 
-- 
/***************************************************
 *Neil Horman
 *Software Engineer
 *Red Hat, Inc.
 *nhorman@redhat.com
 *gpg keyid: 1024D / 0x92A74FA1
 *http://pgp.mit.edu
 ***************************************************/