Commit 954d6235 authored by Julian Wiedmann's avatar Julian Wiedmann Committed by Vasily Gorbik
Browse files

s390/qdio: make thinint registration symmetric 



tiqdio_add_device() adds the device to the tiq_list of eligible targets
for a data IRQ, which gets walked on each QDIO Adapter Interrupt to
inspect their DSCIs.

But currently the tiqdio_add_device() / tiqdio_remove_device() calls
are not symmetric - the device is removed within qdio_shutdown(),
but only added by qdio_activate().
So depending on the call sequence and encountered errors, we might
be trying to remove a list entry in qdio_shutdown() that was never even
added to the list. This required additional INIT_LIST_HEAD() calls to
ensure that the list entry was always in a consistent state.

All drivers now fence the IRQ delivery via qdio_start_irq() /
qdio_stop_irq(), so we can nicely integrate this tiq_list management
with the other steps needed for QDIO Adapter IRQ (de-)registration
(qdio_establish_thinint() / qdio_shutdown_thinint()).
As the naming suggests these get called during qdio_establish() and
qdio_shutdown(), with proper symmetry and roll-back after errors.

With this we longer need to worry about misplaced list removals, and
thus can clean up the list API abuse (INIT_LIST_HEAD() should not be
called on list entries).

Signed-off-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: default avatarBenjamin Block <bblock@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 6bb7a51b

drivers/s390/cio/qdio.h

+0 −2
Original line number Diff line number Diff line
@@ -363,8 +363,6 @@ extern u64 last_ai_time; 
/* prototypes for thin interrupt */

int qdio_establish_thinint(struct qdio_irq *irq_ptr);

void qdio_shutdown_thinint(struct qdio_irq *irq_ptr);

void tiqdio_add_device(struct qdio_irq *irq_ptr);

void tiqdio_remove_device(struct qdio_irq *irq_ptr);

int qdio_thinint_init(void);

void qdio_thinint_exit(void);

int test_nonshared_ind(struct qdio_irq *);

drivers/s390/cio/qdio_main.c

+0 −5
Original line number Diff line number Diff line
@@ -986,7 +986,6 @@ int qdio_shutdown(struct ccw_device *cdev, int how) 
	 */

	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_STOPPED);



	tiqdio_remove_device(irq_ptr);

	qdio_shutdown_queues(irq_ptr);

	qdio_shutdown_debug_entries(irq_ptr);
@@ -1104,7 +1103,6 @@ int qdio_allocate(struct ccw_device *cdev, unsigned int no_input_qs, 
	if (rc)

		goto err_queues;



	INIT_LIST_HEAD(&irq_ptr->entry);

	cdev->private->qdio_data = irq_ptr;

	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_INACTIVE);

	return 0;
@@ -1287,9 +1285,6 @@ int qdio_activate(struct ccw_device *cdev) 
		goto out;

	}



	if (is_thinint_irq(irq_ptr))

		tiqdio_add_device(irq_ptr);



	/* wait for subchannel to become active */

	msleep(5);

drivers/s390/cio/qdio_thinint.c

+12 −18
Original line number Diff line number Diff line
@@ -66,22 +66,6 @@ static void put_indicator(u32 *addr) 
	atomic_dec(&ind->count);

}



void tiqdio_add_device(struct qdio_irq *irq_ptr)

{

	mutex_lock(&tiq_list_lock);

	list_add_rcu(&irq_ptr->entry, &tiq_list);

	mutex_unlock(&tiq_list_lock);

}



void tiqdio_remove_device(struct qdio_irq *irq_ptr)

{

	mutex_lock(&tiq_list_lock);

	list_del_rcu(&irq_ptr->entry);

	mutex_unlock(&tiq_list_lock);

	synchronize_rcu();

	INIT_LIST_HEAD(&irq_ptr->entry);

}



static inline int references_shared_dsci(struct qdio_irq *irq_ptr)

{

	return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
@@ -186,17 +170,27 @@ int qdio_establish_thinint(struct qdio_irq *irq_ptr) 
	DBF_HEX(&irq_ptr->dsci, sizeof(void *));



	rc = set_subchannel_ind(irq_ptr, 0);

	if (rc)

	if (rc) {

		put_indicator(irq_ptr->dsci);



		return rc;

	}



	mutex_lock(&tiq_list_lock);

	list_add_rcu(&irq_ptr->entry, &tiq_list);

	mutex_unlock(&tiq_list_lock);

	return 0;

}



void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)

{

	if (!is_thinint_irq(irq_ptr))

		return;



	mutex_lock(&tiq_list_lock);

	list_del_rcu(&irq_ptr->entry);

	mutex_unlock(&tiq_list_lock);

	synchronize_rcu();



	/* reset adapter interrupt indicators */

	set_subchannel_ind(irq_ptr, 1);

	put_indicator(irq_ptr->dsci);