Commit 1943f53c authored by Michael Holzheu's avatar Michael Holzheu Committed by Martin Schwidefsky
Browse files

[S390] Force PSW restart on online CPU 



PSW restart can be triggered on offline CPUs. If this happens, currently
the PSW restart code fails, because functions like smp_processor_id()
do not work on offline CPUs. This patch fixes this as follows:

If PSW restart is triggered on an offline CPU, the PSW restart (sigp restart)
is done a second time on another CPU that is online and the old CPU is
stopped afterwards.

Signed-off-by: default avatarMichael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent d3bf3795

arch/s390/include/asm/smp.h

+5 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ extern struct save_area *zfcpdump_save_areas[NR_CPUS + 1]; 
extern void smp_switch_to_ipl_cpu(void (*func)(void *), void *);

extern void smp_switch_to_cpu(void (*)(void *), void *, unsigned long sp,

			      int from, int to);

extern void smp_restart_with_online_cpu(void);

extern void smp_restart_cpu(void);



/*
@@ -64,6 +65,10 @@ static inline void smp_switch_to_ipl_cpu(void (*func)(void *), void *data) 
	func(data);

}



static inline void smp_restart_with_online_cpu(void)

{

}



#define smp_vcpu_scheduled	(1)



#endif /* CONFIG_SMP */

arch/s390/kernel/ipl.c

+1 −0
Original line number Diff line number Diff line
@@ -1738,6 +1738,7 @@ static struct kobj_attribute on_restart_attr = 


void do_restart(void)

{

	smp_restart_with_online_cpu();

	smp_send_stop();

	on_restart_trigger.action->fn(&on_restart_trigger);

	stop_run(&on_restart_trigger);

arch/s390/kernel/smp.c

+23 −0
Original line number Diff line number Diff line
@@ -97,6 +97,29 @@ static inline int cpu_stopped(int cpu) 
	return raw_cpu_stopped(cpu_logical_map(cpu));

}



/*

 * Ensure that PSW restart is done on an online CPU

 */

void smp_restart_with_online_cpu(void)

{

	int cpu;



	for_each_online_cpu(cpu) {

		if (stap() == __cpu_logical_map[cpu]) {

			/* We are online: Enable DAT again and return */

			__load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);

			return;

		}

	}

	/* We are not online: Do PSW restart on an online CPU */

	while (sigp(cpu, sigp_restart) == sigp_busy)

		cpu_relax();

	/* And stop ourself */

	while (raw_sigp(stap(), sigp_stop) == sigp_busy)

		cpu_relax();

	for (;;);

}



void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)

{

	struct _lowcore *lc, *current_lc;

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