From 954d6235be412e3de33a43e68ab39342f5eccf9b Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Wed, 30 Sep 2020 10:09:07 +0200 Subject: [PATCH] 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 Reviewed-by: Benjamin Block Signed-off-by: Vasily Gorbik --- drivers/s390/cio/qdio.h | 2 -- drivers/s390/cio/qdio_main.c | 5 ----- drivers/s390/cio/qdio_thinint.c | 30 ++++++++++++------------------ 3 files changed, 12 insertions(+), 25 deletions(-) diff --git a/drivers/s390/cio/qdio.h b/drivers/s390/cio/qdio.h index 4889681370f3..4a4e4de45bc9 100644 --- a/drivers/s390/cio/qdio.h +++ b/drivers/s390/cio/qdio.h @@ -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 *); diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c index 2cc489c9f986..3b1e8ed4ba14 100644 --- a/drivers/s390/cio/qdio_main.c +++ b/drivers/s390/cio/qdio_main.c @@ -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); diff --git a/drivers/s390/cio/qdio_thinint.c b/drivers/s390/cio/qdio_thinint.c index d495bf0200aa..e1b923633372 100644 --- a/drivers/s390/cio/qdio_thinint.c +++ b/drivers/s390/cio/qdio_thinint.c @@ -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); -- 2.25.1