[PATCH] s390: dasd wait for clear i/o interrupt

The sleep_on function clears a running cqr without waiting for the related
interrupt.  This can lead to a panic at the time the interrupt is processed
because the related memory might already be freed.  Wait for clear-interrupt
and de-queue cqr prior to return.

Signed-off-by: Horst Hummel <horst.hummel@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 953097c..abdf1ee 100644 (file)
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -674,11 +674,8 @@ dasd_term_IO(struct dasd_ccw_req * cqr)
                rc = ccw_device_clear(device->cdev, (long) cqr);
                switch (rc) {
                case 0: /* termination successful */
-                       if (cqr->retries > 0) {
-                               cqr->retries--;
-                               cqr->status = DASD_CQR_CLEAR;
-                       } else
-                               cqr->status = DASD_CQR_FAILED;
+                       cqr->retries--;
+                       cqr->status = DASD_CQR_CLEAR;
                        cqr->stopclk = get_clock();
                        DBF_DEV_EVENT(DBF_DEBUG, device,
                                      "terminate cqr %p successful",
@@ -1307,7 +1304,7 @@ dasd_tasklet(struct dasd_device * device)
        /* Now call the callback function of requests with final status */
        list_for_each_safe(l, n, &final_queue) {
                cqr = list_entry(l, struct dasd_ccw_req, list);
-               list_del(&cqr->list);
+               list_del_init(&cqr->list);
                if (cqr->callback != NULL)
                        (cqr->callback)(cqr, cqr->callback_data);
        }
@@ -1392,7 +1389,9 @@ _wait_for_wakeup(struct dasd_ccw_req *cqr)
 
        device = cqr->device;
        spin_lock_irq(get_ccwdev_lock(device->cdev));
-       rc = cqr->status == DASD_CQR_DONE || cqr->status == DASD_CQR_FAILED;
+       rc = ((cqr->status == DASD_CQR_DONE ||
+              cqr->status == DASD_CQR_FAILED) &&
+             list_empty(&cqr->list));
        spin_unlock_irq(get_ccwdev_lock(device->cdev));
        return rc;
 }
@@ -1456,15 +1455,37 @@ dasd_sleep_on_interruptible(struct dasd_ccw_req * cqr)
        while (!finished) {
                rc = wait_event_interruptible(wait_q, _wait_for_wakeup(cqr));
                if (rc != -ERESTARTSYS) {
-                       /* Request status is either done or failed. */
-                       rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
+                       /* Request is final (done or failed) */
+                       rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
                        break;
                }
                spin_lock_irq(get_ccwdev_lock(device->cdev));
-               if (cqr->status == DASD_CQR_IN_IO &&
-                   device->discipline->term_IO(cqr) == 0) {
-                       list_del(&cqr->list);
+               switch (cqr->status) {
+               case DASD_CQR_IN_IO:
+                        /* terminate runnig cqr */
+                       if (device->discipline->term_IO) {
+                               cqr->retries = -1;
+                               device->discipline->term_IO(cqr);
+                               /*nished =
+                                * wait (non-interruptible) for final status
+                                * because signal ist still pending
+                                */
+                               spin_unlock_irq(get_ccwdev_lock(device->cdev));
+                               wait_event(wait_q, _wait_for_wakeup(cqr));
+                               spin_lock_irq(get_ccwdev_lock(device->cdev));
+                               rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
+                               finished = 1;
+                       }
+                       break;
+               case DASD_CQR_QUEUED:
+                       /* request  */
+                       list_del_init(&cqr->list);
+                       rc = -EIO;
                        finished = 1;
+                       break;
+               default:
+                       /* cqr with 'non-interruptable' status - just wait */
+                       break;
                }
                spin_unlock_irq(get_ccwdev_lock(device->cdev));
        }