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2.4: preempt-kernel for MIPS

PATCH New Robert Love 1 participant 1 message May 8, 2002 MIPS

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Robert Love

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PATCH 1/1 2.4: preempt-kernel for MIPS

MontaVista has provided the community with MIPS architecture support for the preemptive kernel patch. Thanks specifically to Jun Sun of MontaVista for the work.

This patch will be integrated with the base 2.4 preempt-kernel patch soon. For now, this is diffed on _top_ of preempt-kernel for 2.4.19-pre8. While it is against 2.4.19-pre8, it should hopefully also apply to a recent MIPS tree checkout.

Comments are welcome. Enjoy,

Robert Love

arch/mips/config.in +1 -0
diff -urN linux-2.4.19-pre8-preempt/arch/mips/config.in linux/arch/mips/config.in
@@ -468,6 +468,7 @@
 #	bool ' Access.Bus support' CONFIG_ACCESSBUS
 #    fi
 fi
+dep_bool 'Preemptible Kernel' CONFIG_PREEMPT $CONFIG_NEW_IRQ
 endmenu
 
 if [ "$CONFIG_ISA" = "y" ]; then
arch/mips/kernel/i8259.c +1 -0
diff -urN linux-2.4.19-pre8-preempt/arch/mips/kernel/i8259.c linux/arch/mips/kernel/i8259.c
@@ -8,6 +8,7 @@
  * Copyright (C) 1992 Linus Torvalds
  * Copyright (C) 1994 - 2000 Ralf Baechle
  */
+#include <linux/sched.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/ioport.h>
arch/mips/kernel/irq.c +28 -1
diff -urN linux-2.4.19-pre8-preempt/arch/mips/kernel/irq.c linux/arch/mips/kernel/irq.c
@@ -8,6 +8,8 @@
  * Copyright (C) 1992 Linus Torvalds
  * Copyright (C) 1994 - 2000 Ralf Baechle
  */
+
+#include <linux/sched.h>
 #include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/delay.h>

@@ -19,11 +21,13 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/random.h>
-#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/ptrace.h>
 
 #include <asm/atomic.h>
 #include <asm/system.h>
 #include <asm/uaccess.h>
+#include <asm/debug.h>
 
 /*
  * Controller mappings for all interrupt sources:

@@ -420,6 +424,8 @@
 	struct irqaction * action;
 	unsigned int status;
 
+	preempt_disable();
+
 	kstat.irqs[cpu][irq]++;
 	spin_lock(&desc->lock);
 	desc->handler->ack(irq);

@@ -481,6 +487,27 @@
 
 	if (softirq_pending(cpu))
 		do_softirq();
+
+#if defined(CONFIG_PREEMPT)
+	while (--current->preempt_count == 0) {
+		db_assert(intr_off());
+		db_assert(!in_interrupt());
+
+		if (current->need_resched == 0) {
+			break;
+		}
+
+		current->preempt_count ++;
+		sti();
+		if (user_mode(regs)) {
+			schedule();
+		} else {
+			preempt_schedule();
+		}
+		cli();
+	}
+#endif
+
 	return 1;
 }
arch/mips/mm/extable.c +1 -0
diff -urN linux-2.4.19-pre8-preempt/arch/mips/mm/extable.c linux/arch/mips/mm/extable.c
@@ -3,6 +3,7 @@
  */
 #include <linux/config.h>
 #include <linux/module.h>
+#include <linux/sched.h>
 #include <linux/spinlock.h>
 #include <asm/uaccess.h>
include/asm-mips/smplock.h +15 -0
diff -urN linux-2.4.19-pre8-preempt/include/asm-mips/smplock.h linux/include/asm-mips/smplock.h
@@ -5,12 +5,21 @@
  *
  * Default SMP lock implementation
  */
+#include <linux/config.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 
 extern spinlock_t kernel_flag;
 
+#ifdef CONFIG_SMP
 #define kernel_locked()		spin_is_locked(&kernel_flag)
+#else
+#ifdef CONFIG_PREEMPT
+#define kernel_locked()         preempt_get_count()
+#else
+#define kernel_locked()         1
+#endif
+#endif
 
 /*
  * Release global kernel lock and global interrupt lock

@@ -42,8 +51,14 @@
  */
 extern __inline__ void lock_kernel(void)
 {
+#ifdef CONFIG_PREEMPT
+	if (current->lock_depth == -1)
+		spin_lock(&kernel_flag);
+	++current->lock_depth;
+#else
 	if (!++current->lock_depth)
 		spin_lock(&kernel_flag);
+#endif
 }
 
 extern __inline__ void unlock_kernel(void)
include/asm-mips/softirq.h +3 -0
diff -urN linux-2.4.19-pre8-preempt/include/asm-mips/softirq.h linux/include/asm-mips/softirq.h
@@ -15,6 +15,7 @@
 
 static inline void cpu_bh_disable(int cpu)
 {
+	preempt_disable();
 	local_bh_count(cpu)++;
 	barrier();
 }

@@ -23,6 +24,7 @@
 {
 	barrier();
 	local_bh_count(cpu)--;
+	preempt_enable();
 }
 
 

@@ -36,6 +38,7 @@
 	cpu = smp_processor_id();				\
 	if (!--local_bh_count(cpu) && softirq_pending(cpu))	\
 		do_softirq();					\
+	preempt_enable();                                       \
 } while (0)
 
 #define in_softirq() (local_bh_count(smp_processor_id()) != 0)
include/asm-mips/system.h +12 -0
diff -urN linux-2.4.19-pre8-preempt/include/asm-mips/system.h linux/include/asm-mips/system.h
@@ -285,4 +285,16 @@
 #define die_if_kernel(msg, regs)					\
 	__die_if_kernel(msg, regs, __FILE__ ":"__FUNCTION__, __LINE__)
 
+extern __inline__ int intr_on(void)
+{
+	unsigned long flags;
+	save_flags(flags);
+	return flags & 1;
+}
+
+extern __inline__ int intr_off(void)
+{
+	return ! intr_on();
+}
+
 #endif /* _ASM_SYSTEM_H */