linux-kernel - [PATCH 1/2] Preempt realtime Oops syslog

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Message-Id: <1203133483.10893.25.camel@dhcp140.mvista.com>
Date:	Fri, 15 Feb 2008 19:44:43 -0800
From:	Min Zhang <mzhang@...sta.com>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] Preempt realtime Oops syslog

Add bust_spinlocks when kernel die from do_trap to flush Oops
dump to syslog immediatly. Oops is missing from syslog if it is from
non-preemptible section, because on PREEMPT_RT kernel, Oops printk
doesn't wake up klogd from non-preemptible context; see
release_console_sem in kernel/printk.c. 

Tested by Oops in module_init and insmod that kernel module. The
Oops is in non-preemptive context because modules are loaded from 
inside a realtime priority thread in a preemptive realtime kernel. 

Only apply to PPC arch because bust_spinlocks has already been used 
by x86 and other architectures

Signed-off-by: Min Zhang <mzhang@...sta.com>

Index: rt-2.6/arch/ppc/kernel/traps.c
===================================================================
--- rt-2.6.orig/arch/ppc/kernel/traps.c
+++ rt-2.6/arch/ppc/kernel/traps.c
@@ -92,6 +92,7 @@ int die(const char * str, struct pt_regs
 	if (nl)
 		printk("\n");
 	show_regs(fp);
+	bust_spinlocks(0);
 	add_taint(TAINT_DIE);
 	spin_unlock_irq(&die_lock);
 	/* do_exit() should take care of panic'ing from an interrupt

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