[Crash-utility] crash vs irqs

[D. Hugh Redelmeier]

| From: Dave Anderson <anderson at redhat.com>

| D. Hugh Redelmeier wrote:
| > I'm having a problem with the Fedora 7 kernel 2.6.21-1.3228.fc7 for
| > x86_64.  So I am trying to use crash-4.0-4.2 to analyze the problem.
| > (The version of crash in F7 won't work with this kernel.)

| > When I use the irq command I get this error message:
| >   irq: cannot determine size of irq_desc_t
| 
| Could be shifting sands syndrome, which happens all the time.
| 
| Perhaps "irq_desc_t" has been removed from that kernel?
| I've got a slightly older 2.6.21-1.3125.fc7 source tree
| hanging around that shows this:
| 
| /*
|  * Migration helpers for obsolete names, they will go away:
|  */
| #define hw_interrupt_type       irq_chip
| typedef struct irq_chip         hw_irq_controller;
| #define no_irq_type             no_irq_chip
| typedef struct irq_desc         irq_desc_t;
| 
| Interesting, the "go away" comment -- perhaps it's no longer
| there in -1.3228?

I'm playing with linux-2.6.22-rc7 now.  It has the same problem with
the crash irq command.

Those lines are still in
  linux-2.6.22-rc7/include/linux/irq.h
so I don't know why this problem has come up.

In any case, I have a patch that seems to fix the problem and that
should be backward compatible.  It is based on the suggestions you
outlined.  I'm starting with the crash-4.0-4.3.

===================================================================
RCS file: RCS/kernel.c,v
retrieving revision 1.1
diff -u -r1.1 kernel.c
--- kernel.c	2007/07/07 17:23:06	1.1
+++ kernel.c	2007/07/07 17:56:59
@@ -49,7 +49,7 @@
 static void BUG_bytes_init(void);
 static int BUG_x86(void);
 static int BUG_x86_64(void);
-
+static /*const*/ char *irq_desc_type_name;	
 
 
 /*
@@ -278,13 +278,19 @@
 	STRUCT_SIZE_INIT(hlist_head, "hlist_head"); 
 	STRUCT_SIZE_INIT(hlist_node, "hlist_node"); 
 
-	MEMBER_OFFSET_INIT(irq_desc_t_status,  "irq_desc_t", "status");
-	if (MEMBER_EXISTS("irq_desc_t", "handler"))
-		MEMBER_OFFSET_INIT(irq_desc_t_handler, "irq_desc_t", "handler");
+	/* see linux-* /include/linux/irq.h to find how IRQ information is represented by the kernel */
+	if (STRUCT_EXISTS("irq_desc_t"))
+	    irq_desc_type_name = "irq_desc_t";
+	else
+	    irq_desc_type_name = "irq_desc";
+
+	MEMBER_OFFSET_INIT(irq_desc_t_status,  irq_desc_type_name, "status");
+	if (MEMBER_EXISTS(irq_desc_type_name, "handler"))
+		MEMBER_OFFSET_INIT(irq_desc_t_handler, irq_desc_type_name, "handler");
 	else
-		MEMBER_OFFSET_INIT(irq_desc_t_chip, "irq_desc_t", "chip");
-	MEMBER_OFFSET_INIT(irq_desc_t_action, "irq_desc_t", "action");
-	MEMBER_OFFSET_INIT(irq_desc_t_depth, "irq_desc_t", "depth");
+		MEMBER_OFFSET_INIT(irq_desc_t_chip, irq_desc_type_name, "chip");
+	MEMBER_OFFSET_INIT(irq_desc_t_action, irq_desc_type_name, "action");
+	MEMBER_OFFSET_INIT(irq_desc_t_depth, irq_desc_type_name, "depth");
 	if (STRUCT_EXISTS("hw_interrupt_type")) {
 		MEMBER_OFFSET_INIT(hw_interrupt_type_typename,
 			"hw_interrupt_type", "typename");
@@ -346,7 +352,7 @@
 	MEMBER_OFFSET_INIT(irqaction_dev_id, "irqaction", "dev_id");
 	MEMBER_OFFSET_INIT(irqaction_next, "irqaction", "next");
 
-	STRUCT_SIZE_INIT(irq_desc_t, "irq_desc_t");
+	STRUCT_SIZE_INIT(irq_desc_t, irq_desc_type_name);
 
         STRUCT_SIZE_INIT(irq_cpustat_t, "irq_cpustat_t");
         MEMBER_OFFSET_INIT(irq_cpustat_t___softirq_active, 
================ end of patch ================