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Message-ID: <20070319130123.GA1292@skybase>
Date: Mon, 19 Mar 2007 14:01:23 +0100
From: Martin Schwidefsky <schwidefsky@...ibm.com>
To: linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Cc: rwuerthn@...ibm.com
Subject: [S390] zcrypt: fix possible dead lock in AP bus module
From: Ralph Wuerthner <rwuerthn@...ibm.com>
[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 <rwuerthn@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
---
drivers/s390/crypto/ap_bus.c | 30 +++++++++++++++++++++++-------
drivers/s390/crypto/ap_bus.h | 1 +
2 files changed, 24 insertions(+), 7 deletions(-)
diff -urpN linux-2.6/drivers/s390/crypto/ap_bus.c linux-2.6-patched/drivers/s390/crypto/ap_bus.c
--- linux-2.6/drivers/s390/crypto/ap_bus.c 2007-03-19 13:09:04.000000000 +0100
+++ linux-2.6-patched/drivers/s390/crypto/ap_bus.c 2007-03-19 13:09:26.000000000 +0100
@@ -65,6 +65,8 @@ module_param_named(poll_thread, ap_threa
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
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 devic
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_stru
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 lon
* 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 *
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 -urpN linux-2.6/drivers/s390/crypto/ap_bus.h linux-2.6-patched/drivers/s390/crypto/ap_bus.h
--- linux-2.6/drivers/s390/crypto/ap_bus.h 2007-02-04 19:44:54.000000000 +0100
+++ linux-2.6-patched/drivers/s390/crypto/ap_bus.h 2007-03-19 13:09:26.000000000 +0100
@@ -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.*/
-
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