Commit df7997ab authored by Heiko Carstens's avatar Heiko Carstens
Browse files

[S390] irq: fix service signal external interrupt handling 



Interrupt sources like pfault, sclp, dasd_diag and virtio all use the
service signal external interrupt subclass mask in control register 0
to enable and disable the corresponding interrupt.
Because no reference counting is implemented each subsystem thinks it
is the only user of subclass and sets and clears the bit like it wants.
This leads to case that unloading the dasd diag module under z/VM
causes both sclp and pfault interrupts to be masked. The result will
be locked up system sooner or later.
Fix this by introducing a new way to set (register) and clear
(unregister) the service signal subclass mask bit in cr0.
Also convert all drivers.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 902050bc

arch/s390/include/asm/s390_ext.h

+2 −0
Original line number Diff line number Diff line
@@ -13,5 +13,7 @@ typedef void (*ext_int_handler_t)(unsigned int, unsigned int, unsigned long); 


int register_external_interrupt(__u16 code, ext_int_handler_t handler);

int unregister_external_interrupt(__u16 code, ext_int_handler_t handler);

void service_subclass_irq_register(void);

void service_subclass_irq_unregister(void);



#endif /* _S390_EXTINT_H */

arch/s390/kernel/s390_ext.c

+23 −0
Original line number Diff line number Diff line
@@ -106,3 +106,26 @@ void __irq_entry do_extint(struct pt_regs *regs, unsigned int ext_int_code, 
	irq_exit();

	set_irq_regs(old_regs);

}



static DEFINE_SPINLOCK(sc_irq_lock);

static int sc_irq_refcount;



void service_subclass_irq_register(void)

{

	spin_lock(&sc_irq_lock);

	if (!sc_irq_refcount)

		ctl_set_bit(0, 9);

	sc_irq_refcount++;

	spin_unlock(&sc_irq_lock);

}

EXPORT_SYMBOL(service_subclass_irq_register);



void service_subclass_irq_unregister(void)

{

	spin_lock(&sc_irq_lock);

	sc_irq_refcount--;

	if (!sc_irq_refcount)

		ctl_clear_bit(0, 9);

	spin_unlock(&sc_irq_lock);

}

EXPORT_SYMBOL(service_subclass_irq_unregister);

arch/s390/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -613,7 +613,7 @@ static int __init pfault_irq_init(void) 
	rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;

	if (rc)

		goto out_pfault;

	ctl_set_bit(0, 9);

	service_subclass_irq_register();

	hotcpu_notifier(pfault_cpu_notify, 0);

	return 0;

drivers/s390/block/dasd_diag.c

+2 −2
Original line number Diff line number Diff line
@@ -642,7 +642,7 @@ dasd_diag_init(void) 
	}

	ASCEBC(dasd_diag_discipline.ebcname, 4);



	ctl_set_bit(0, 9);

	service_subclass_irq_register();

	register_external_interrupt(0x2603, dasd_ext_handler);

	dasd_diag_discipline_pointer = &dasd_diag_discipline;

	return 0;
@@ -652,7 +652,7 @@ static void __exit 
dasd_diag_cleanup(void)

{

	unregister_external_interrupt(0x2603, dasd_ext_handler);

	ctl_clear_bit(0, 9);

	service_subclass_irq_unregister();

	dasd_diag_discipline_pointer = NULL;

}

drivers/s390/char/sclp.c

+3 −3
Original line number Diff line number Diff line
@@ -885,12 +885,12 @@ sclp_check_interface(void) 
		spin_unlock_irqrestore(&sclp_lock, flags);

		/* Enable service-signal interruption - needs to happen

		 * with IRQs enabled. */

		ctl_set_bit(0, 9);

		service_subclass_irq_register();

		/* Wait for signal from interrupt or timeout */

		sclp_sync_wait();

		/* Disable service-signal interruption - needs to happen

		 * with IRQs enabled. */

		ctl_clear_bit(0,9);

		service_subclass_irq_unregister();

		spin_lock_irqsave(&sclp_lock, flags);

		del_timer(&sclp_request_timer);

		if (sclp_init_req.status == SCLP_REQ_DONE &&
@@ -1070,7 +1070,7 @@ sclp_init(void) 
	spin_unlock_irqrestore(&sclp_lock, flags);

	/* Enable service-signal external interruption - needs to happen with

	 * IRQs enabled. */

	ctl_set_bit(0, 9);

	service_subclass_irq_register();

	sclp_init_mask(1);

	return 0;

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