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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: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Julian Wiedmann 2020-09-30 10:09:07 +02:00 committed by Vasily Gorbik
parent 6bb7a51b60
commit 954d6235be
3 changed files with 12 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/s390/cio/qdio.h
View File

@ -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 *);

5
drivers/s390/cio/qdio_main.c
View File

@ -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);

30
drivers/s390/cio/qdio_thinint.c
View File

@ -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;
@ -186,10 +170,15 @@ 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;
}
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)
@ -197,6 +186,11 @@ 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);