From: Ralph Wuerthner Date: Mon, 19 Mar 2007 12:19:14 +0000 (+0100) Subject: [S390] zcrypt: fix possible dead lock in AP bus module X-Git-Tag: v2.6.21-rc5~55^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf352ce0b9104dc6a1c11df52db9f910f1f6cd2e;p=linux-2.6 [S390] zcrypt: fix possible dead lock in AP bus module AP bus module uses bus_for_each_dev() in software interrupt context to poll for completed requests which might cause dead locks. Solution: use private AP device list for polling in software interrupt context. Signed-off-by: Ralph Wuerthner Signed-off-by: Martin Schwidefsky --- diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c index c7d1355237..181b51772b 100644 --- a/drivers/s390/crypto/ap_bus.c +++ b/drivers/s390/crypto/ap_bus.c @@ -65,6 +65,8 @@ module_param_named(poll_thread, ap_thread_flag, int, 0000); MODULE_PARM_DESC(poll_thread, "Turn on/off poll thread, default is 1 (on)."); static struct device *ap_root_device = NULL; +static DEFINE_SPINLOCK(ap_device_lock); +static LIST_HEAD(ap_device_list); /** * Workqueue & timer for bus rescan. @@ -457,6 +459,9 @@ static int ap_device_probe(struct device *dev) int rc; ap_dev->drv = ap_drv; + spin_lock_bh(&ap_device_lock); + list_add(&ap_dev->list, &ap_device_list); + spin_unlock_bh(&ap_device_lock); rc = ap_drv->probe ? ap_drv->probe(ap_dev) : -ENODEV; return rc; } @@ -497,6 +502,9 @@ static int ap_device_remove(struct device *dev) ap_flush_queue(ap_dev); if (ap_drv->remove) ap_drv->remove(ap_dev); + spin_lock_bh(&ap_device_lock); + list_del_init(&ap_dev->list); + spin_unlock_bh(&ap_device_lock); return 0; } @@ -772,6 +780,7 @@ static void ap_scan_bus(struct work_struct *unused) spin_lock_init(&ap_dev->lock); INIT_LIST_HEAD(&ap_dev->pendingq); INIT_LIST_HEAD(&ap_dev->requestq); + INIT_LIST_HEAD(&ap_dev->list); if (device_type == 0) ap_probe_device_type(ap_dev); else @@ -1033,14 +1042,13 @@ static void ap_poll_timeout(unsigned long unused) * polling until bit 2^0 of the control flags is not set. If bit 2^1 * of the control flags has been set arm the poll timer. */ -static int __ap_poll_all(struct device *dev, void *data) +static int __ap_poll_all(struct ap_device *ap_dev, unsigned long *flags) { - struct ap_device *ap_dev = to_ap_dev(dev); int rc; spin_lock(&ap_dev->lock); if (!ap_dev->unregistered) { - rc = ap_poll_queue(to_ap_dev(dev), (unsigned long *) data); + rc = ap_poll_queue(ap_dev, flags); if (rc) ap_dev->unregistered = 1; } else @@ -1054,10 +1062,15 @@ static int __ap_poll_all(struct device *dev, void *data) static void ap_poll_all(unsigned long dummy) { unsigned long flags; + struct ap_device *ap_dev; do { flags = 0; - bus_for_each_dev(&ap_bus_type, NULL, &flags, __ap_poll_all); + spin_lock(&ap_device_lock); + list_for_each_entry(ap_dev, &ap_device_list, list) { + __ap_poll_all(ap_dev, &flags); + } + spin_unlock(&ap_device_lock); } while (flags & 1); if (flags & 2) ap_schedule_poll_timer(); @@ -1075,6 +1088,7 @@ static int ap_poll_thread(void *data) DECLARE_WAITQUEUE(wait, current); unsigned long flags; int requests; + struct ap_device *ap_dev; set_user_nice(current, 19); while (1) { @@ -1092,10 +1106,12 @@ static int ap_poll_thread(void *data) set_current_state(TASK_RUNNING); remove_wait_queue(&ap_poll_wait, &wait); - local_bh_disable(); flags = 0; - bus_for_each_dev(&ap_bus_type, NULL, &flags, __ap_poll_all); - local_bh_enable(); + spin_lock_bh(&ap_device_lock); + list_for_each_entry(ap_dev, &ap_device_list, list) { + __ap_poll_all(ap_dev, &flags); + } + spin_unlock_bh(&ap_device_lock); } set_current_state(TASK_RUNNING); remove_wait_queue(&ap_poll_wait, &wait); diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h index 83b69c01cd..008559ea74 100644 --- a/drivers/s390/crypto/ap_bus.h +++ b/drivers/s390/crypto/ap_bus.h @@ -106,6 +106,7 @@ struct ap_device { struct device device; struct ap_driver *drv; /* Pointer to AP device driver. */ spinlock_t lock; /* Per device lock. */ + struct list_head list; /* private list of all AP devices. */ ap_qid_t qid; /* AP queue id. */ int queue_depth; /* AP queue depth.*/