From 9af3e04ee41e6841b2accb9dc96562bcf4e59916 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Wed, 21 Sep 2016 14:12:53 +0200 Subject: s390/zcrypt: get rid of ap_poll_requests The poll thread of the AP bus is burning CPU while waiting for crypto requests to complete. We can as well burn a few more cycles in the poll thread to check if there are pending requests and remove the atomic operations with the ap_poll_requests. This improves the code if the machine has adapter interrupts. Signed-off-by: Harald Freudenberger Signed-off-by: Martin Schwidefsky --- drivers/s390/crypto/ap_bus.c | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) (limited to 'drivers/s390') diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c index f6de22a4f7d9..fe1cfa4b22c9 100644 --- a/drivers/s390/crypto/ap_bus.c +++ b/drivers/s390/crypto/ap_bus.c @@ -91,7 +91,6 @@ static DECLARE_WORK(ap_scan_work, ap_scan_bus); */ static void ap_tasklet_fn(unsigned long); static DECLARE_TASKLET(ap_tasklet, ap_tasklet_fn, 0); -static atomic_t ap_poll_requests = ATOMIC_INIT(0); static DECLARE_WAIT_QUEUE_HEAD(ap_poll_wait); static struct task_struct *ap_poll_kthread = NULL; static DEFINE_MUTEX(ap_poll_thread_mutex); @@ -419,7 +418,6 @@ static struct ap_queue_status ap_sm_recv(struct ap_device *ap_dev) ap_dev->reply->message, ap_dev->reply->length); switch (status.response_code) { case AP_RESPONSE_NORMAL: - atomic_dec(&ap_poll_requests); ap_dev->queue_count--; if (ap_dev->queue_count > 0) mod_timer(&ap_dev->timeout, @@ -436,7 +434,6 @@ static struct ap_queue_status ap_sm_recv(struct ap_device *ap_dev) if (!status.queue_empty || ap_dev->queue_count <= 0) break; /* The card shouldn't forget requests but who knows. */ - atomic_sub(ap_dev->queue_count, &ap_poll_requests); ap_dev->queue_count = 0; list_splice_init(&ap_dev->pendingq, &ap_dev->requestq); ap_dev->requestq_count += ap_dev->pendingq_count; @@ -524,7 +521,6 @@ static enum ap_wait ap_sm_write(struct ap_device *ap_dev) ap_msg->message, ap_msg->length, ap_msg->special); switch (status.response_code) { case AP_RESPONSE_NORMAL: - atomic_inc(&ap_poll_requests); ap_dev->queue_count++; if (ap_dev->queue_count == 1) mod_timer(&ap_dev->timeout, @@ -796,6 +792,27 @@ static void ap_tasklet_fn(unsigned long dummy) ap_sm_wait(wait); } +static int ap_pending_requests(void) +{ + struct ap_device *ap_dev; + int id, pending = 0; + + for (id = 0; pending == 0 && id < AP_DEVICES; id++) { + spin_lock_bh(&ap_device_list_lock); + list_for_each_entry(ap_dev, &ap_device_list, list) { + spin_lock_bh(&ap_dev->lock); + if (ap_dev->queue_count) + pending = 1; + spin_unlock_bh(&ap_dev->lock); + if (pending) + break; + } + spin_unlock_bh(&ap_device_list_lock); + } + + return pending; +} + /** * ap_poll_thread(): Thread that polls for finished requests. * @data: Unused pointer @@ -815,8 +832,7 @@ static int ap_poll_thread(void *data) while (!kthread_should_stop()) { add_wait_queue(&ap_poll_wait, &wait); set_current_state(TASK_INTERRUPTIBLE); - if (ap_suspend_flag || - atomic_read(&ap_poll_requests) <= 0) { + if (ap_suspend_flag || !ap_pending_requests()) { schedule(); try_to_freeze(); } @@ -828,7 +844,8 @@ static int ap_poll_thread(void *data) continue; } ap_tasklet_fn(0); - } while (!kthread_should_stop()); + } + return 0; } @@ -1267,9 +1284,6 @@ static int ap_device_remove(struct device *dev) spin_unlock_bh(&ap_device_list_lock); if (ap_drv->remove) ap_drv->remove(ap_dev); - spin_lock_bh(&ap_dev->lock); - atomic_sub(ap_dev->queue_count, &ap_poll_requests); - spin_unlock_bh(&ap_dev->lock); return 0; } -- cgit