s390/dasd: simplify locking in dasd_times_out

Provide __dasd_cancel_req that is called with the ccw device lock
held to simplify the locking in dasd_times_out. Also this removes
the following sparse warning:
context imbalance in 'dasd_times_out' - different lock contexts for basic block

Note: with this change dasd_schedule_device_bh is now called (via
dasd_cancel_req) with the ccw device lock held. But is is already
the case for other codepaths.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 17 insertions, 14 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 04143c08bd6e..f401b4c38cfc 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -2569,14 +2569,11 @@ EXPORT_SYMBOL(dasd_sleep_on_immediatly);
  * Cancellation of a request is an asynchronous operation! The calling
  * function has to wait until the request is properly returned via callback.
  */
-int dasd_cancel_req(struct dasd_ccw_req *cqr)
+static int __dasd_cancel_req(struct dasd_ccw_req *cqr)
 {
         struct dasd_device *device = cqr->startdev;
-        unsigned long flags;
-        int rc;
+        int rc = 0;
 
-        rc = 0;
-        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
         switch (cqr->status) {
         case DASD_CQR_QUEUED:
                 /* request was not started - just set to cleared */
@@ -2596,11 +2593,21 @@ int dasd_cancel_req(struct dasd_ccw_req *cqr)
         default: /* already finished or clear pending - do nothing */
                 break;
         }
-        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
         dasd_schedule_device_bh(device);
         return rc;
 }
-EXPORT_SYMBOL(dasd_cancel_req);
+
+int dasd_cancel_req(struct dasd_ccw_req *cqr)
+{
+        struct dasd_device *device = cqr->startdev;
+        unsigned long flags;
+        int rc;
+
+        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
+        rc = __dasd_cancel_req(cqr);
+        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
+        return rc;
+}
 
 /*
  * SECTION: Operations of the dasd_block layer.
@@ -3082,12 +3089,10 @@ enum blk_eh_timer_return dasd_times_out(struct request *req, bool reserved)
         cqr->retries = -1;
         cqr->intrc = -ETIMEDOUT;
         if (cqr->status >= DASD_CQR_QUEUED) {
-                spin_unlock(get_ccwdev_lock(device->cdev));
-                rc = dasd_cancel_req(cqr);
+                rc = __dasd_cancel_req(cqr);
         } else if (cqr->status == DASD_CQR_FILLED ||
                    cqr->status == DASD_CQR_NEED_ERP) {
                 cqr->status = DASD_CQR_TERMINATED;
-                spin_unlock(get_ccwdev_lock(device->cdev));
         } else if (cqr->status == DASD_CQR_IN_ERP) {
                 struct dasd_ccw_req *searchcqr, *nextcqr, *tmpcqr;
 
@@ -3102,9 +3107,7 @@ enum blk_eh_timer_return dasd_times_out(struct request *req, bool reserved)
                         searchcqr->retries = -1;
                         searchcqr->intrc = -ETIMEDOUT;
                         if (searchcqr->status >= DASD_CQR_QUEUED) {
-                                spin_unlock(get_ccwdev_lock(device->cdev));
-                                rc = dasd_cancel_req(searchcqr);
-                                spin_lock(get_ccwdev_lock(device->cdev));
+                                rc = __dasd_cancel_req(searchcqr);
                         } else if ((searchcqr->status == DASD_CQR_FILLED) ||
                                    (searchcqr->status == DASD_CQR_NEED_ERP)) {
                                 searchcqr->status = DASD_CQR_TERMINATED;
@@ -3118,8 +3121,8 @@ enum blk_eh_timer_return dasd_times_out(struct request *req, bool reserved)
                         }
                         break;
                 }
-                spin_unlock(get_ccwdev_lock(device->cdev));
         }
+        spin_unlock(get_ccwdev_lock(device->cdev));
         dasd_schedule_block_bh(block);
         spin_unlock(&block->queue_lock);
         spin_unlock_irqrestore(&cqr->dq->lock, flags);