[APIC] Avoid change apic_id failure panic

[Herbert Xu]

Hi:

I've received two reports at http://bugs.debian.org/251207 where
ioapic caused machines to lock up during booting due to the
change apic_id panic in arch/i386/kernel/io_apic.c.

Since it appears that we can avoid panicking at all, I think we
should replace the panic calls with the following patch which
attempts to continue after the failure.

I've also done the same thing to the other panic() call in the
same function.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email:  Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
#   2004/05/21 23:24:33+10:00 herbert@xxxxxxxxxxxxxxxxxxx 
#   [APIC] Avoid panic in io_apic_get_unique_id.
# 
# arch/i386/kernel/mpparse.c
#   2004/05/21 23:24:02+10:00 herbert@xxxxxxxxxxxxxxxxxxx +9 -2
#   Avoid panic in io_apic_get_unique_id.
# 
# arch/i386/kernel/io_apic.c
#   2004/05/21 23:24:02+10:00 herbert@xxxxxxxxxxxxxxxxxxx +12 -7
#   Avoid panic in io_apic_get_unique_id.
# 
diff -Nru a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
--- a/arch/i386/kernel/io_apic.c	2004-06-03 20:02:42 +10:00
+++ b/arch/i386/kernel/io_apic.c	2004-06-03 20:02:42 +10:00
@@ -2365,8 +2365,10 @@
 				break;
 		}
 
-		if (i == IO_APIC_MAX_ID)
-			panic("Max apic_id exceeded!\n");
+		if (i == IO_APIC_MAX_ID) {
+			printk(KERN_ERR "Max apic_id exceeded!\n");
+			return -1;
+		}
 
 		printk(KERN_WARNING "IOAPIC[%d]: apic_id %d already used, "
 			"trying %d\n", ioapic, apic_id, i);
@@ -2374,9 +2376,6 @@
 		apic_id = i;
 	} 
 
-	tmp = apicid_to_cpu_present(apic_id);
-	physids_or(apic_id_map, apic_id_map, tmp);
-
 	if (reg_00.bits.ID != apic_id) {
 		reg_00.bits.ID = apic_id;
 
@@ -2386,9 +2385,15 @@
 		spin_unlock_irqrestore(&ioapic_lock, flags);
 
 		/* Sanity check */
-		if (reg_00.bits.ID != apic_id)
-			panic("IOAPIC[%d]: Unable change apic_id!\n", ioapic);
+		if (reg_00.bits.ID != apic_id) {
+			printk(KERN_ERR "IOAPIC[%d]: Unable change apic_id!\n",
+			       ioapic);
+			return -1;
+		}
 	}
+
+	tmp = apicid_to_cpu_present(apic_id);
+	physids_or(apic_id_map, apic_id_map, tmp);
 
 	printk(KERN_INFO "IOAPIC[%d]: Assigned apic_id %d\n", ioapic, apic_id);
 
diff -Nru a/arch/i386/kernel/mpparse.c b/arch/i386/kernel/mpparse.c
--- a/arch/i386/kernel/mpparse.c	2004-06-03 20:02:41 +10:00
+++ b/arch/i386/kernel/mpparse.c	2004-06-03 20:02:41 +10:00
@@ -881,6 +881,7 @@
 	u32			gsi_base)
 {
 	int			idx = 0;
+	int			apicid;
 
 	if (nr_ioapics >= MAX_IO_APICS) {
 		printk(KERN_ERR "ERROR: Max # of I/O APICs (%d) exceeded "
@@ -893,14 +894,19 @@
 		return;
 	}
 
-	idx = nr_ioapics++;
+	idx = nr_ioapics;
 
 	mp_ioapics[idx].mpc_type = MP_IOAPIC;
 	mp_ioapics[idx].mpc_flags = MPC_APIC_USABLE;
 	mp_ioapics[idx].mpc_apicaddr = address;
 
 	set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
-	mp_ioapics[idx].mpc_apicid = io_apic_get_unique_id(idx, id);
+	apicid = io_apic_get_unique_id(idx, id);
+	if (apicid < 0) {
+		clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
+		return;
+	}
+	mp_ioapics[idx].mpc_apicid = apicid;
 	mp_ioapics[idx].mpc_apicver = io_apic_get_version(idx);
 	
 	/* 
@@ -912,6 +918,7 @@
 	mp_ioapic_routing[idx].gsi_end = gsi_base + 
 		io_apic_get_redir_entries(idx);
 
+	nr_ioapics++;
 	printk("IOAPIC[%d]: apic_id %d, version %d, address 0x%lx, "
 		"GSI %d-%d\n", idx, mp_ioapics[idx].mpc_apicid, 
 		mp_ioapics[idx].mpc_apicver, mp_ioapics[idx].mpc_apicaddr,