[S390] cio: make steal lock procedure more robust

An Unconditional Reserve + Release operation (steal lock) for a
boxed device may fail when encountering special error cases
(e.g. unit checks or path errors). Fix this by using the more
robust ccw_request infrastructure for performing the steal lock
CCW program.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

4 files changed, 134 insertions, 89 deletions

diff --git a/drivers/s390/cio/device.h b/drivers/s390/cio/device.h
index 2df519bb877e..bcfe13e42638 100644
--- a/drivers/s390/cio/device.h
+++ b/drivers/s390/cio/device.h
@@ -28,6 +28,7 @@ enum dev_state {
         DEV_STATE_DISCONNECTED_SENSE_ID,
         DEV_STATE_CMFCHANGE,
         DEV_STATE_CMFUPDATE,
+        DEV_STATE_STEAL_LOCK,
         /* last element! */
         NR_DEV_STATES
 };
@@ -116,6 +117,9 @@ void ccw_device_verify_done(struct ccw_device *, int);
 void ccw_device_disband_start(struct ccw_device *);
 void ccw_device_disband_done(struct ccw_device *, int);
 
+void ccw_device_stlck_start(struct ccw_device *, void *, void *, void *);
+void ccw_device_stlck_done(struct ccw_device *, void *, int);
+
 int ccw_device_call_handler(struct ccw_device *);
 
 int ccw_device_stlck(struct ccw_device *);
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index 8d565ff85e43..7d42417bc2c7 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -641,6 +641,23 @@ ccw_device_online_verify(struct ccw_device *cdev, enum dev_event dev_event)
 }
 
 /*
+ * Handle path verification event in boxed state.
+ */
+static void ccw_device_boxed_verify(struct ccw_device *cdev,
+                                    enum dev_event dev_event)
+{
+        struct subchannel *sch = to_subchannel(cdev->dev.parent);
+
+        if (cdev->online) {
+                if (cio_enable_subchannel(sch, (u32) (addr_t) sch))
+                        ccw_device_done(cdev, DEV_STATE_NOT_OPER);
+                else
+                        ccw_device_online_verify(cdev, dev_event);
+        } else
+                css_schedule_eval(sch->schid);
+}
+
+/*
  * Got an interrupt for a normal io (state online).
  */
 static void
@@ -817,32 +834,6 @@ ccw_device_delay_verify(struct ccw_device *cdev, enum dev_event dev_event)
 }
 
 static void
-ccw_device_stlck_done(struct ccw_device *cdev, enum dev_event dev_event)
-{
-        struct irb *irb;
-
-        switch (dev_event) {
-        case DEV_EVENT_INTERRUPT:
-                irb = (struct irb *) __LC_IRB;
-                /* Check for unsolicited interrupt. */
-                if ((scsw_stctl(&irb->scsw) ==
-                     (SCSW_STCTL_STATUS_PEND | SCSW_STCTL_ALERT_STATUS)) &&
-                    (!scsw_cc(&irb->scsw)))
-                        /* FIXME: we should restart stlck here, but this
-                         * is extremely unlikely ... */
-                        goto out_wakeup;
-
-                ccw_device_accumulate_irb(cdev, irb);
-                /* We don't care about basic sense etc. */
-                break;
-        default: /* timeout */
-                break;
-        }
-out_wakeup:
-        wake_up(&cdev->private->wait_q);
-}
-
-static void
 ccw_device_start_id(struct ccw_device *cdev, enum dev_event dev_event)
 {
         struct subchannel *sch;
@@ -1010,9 +1001,9 @@ fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
         },
         [DEV_STATE_BOXED] = {
                 [DEV_EVENT_NOTOPER]     = ccw_device_generic_notoper,
-                [DEV_EVENT_INTERRUPT]   = ccw_device_stlck_done,
-                [DEV_EVENT_TIMEOUT]     = ccw_device_stlck_done,
-                [DEV_EVENT_VERIFY]      = ccw_device_nop,
+                [DEV_EVENT_INTERRUPT]   = ccw_device_nop,
+                [DEV_EVENT_TIMEOUT]     = ccw_device_nop,
+                [DEV_EVENT_VERIFY]      = ccw_device_boxed_verify,
         },
         /* states to wait for i/o completion before doing something */
         [DEV_STATE_TIMEOUT_KILL] = {
@@ -1052,6 +1043,12 @@ fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
                 [DEV_EVENT_TIMEOUT]     = ccw_device_update_cmfblock,
                 [DEV_EVENT_VERIFY]      = ccw_device_update_cmfblock,
         },
+        [DEV_STATE_STEAL_LOCK] = {
+                [DEV_EVENT_NOTOPER]     = ccw_device_request_event,
+                [DEV_EVENT_INTERRUPT]   = ccw_device_request_event,
+                [DEV_EVENT_TIMEOUT]     = ccw_device_request_event,
+                [DEV_EVENT_VERIFY]      = ccw_device_nop,
+        },
 };
 
 EXPORT_SYMBOL_GPL(ccw_device_set_timeout);
diff --git a/drivers/s390/cio/device_ops.c b/drivers/s390/cio/device_ops.c
index d4be16acebe4..6da84543dfe9 100644
--- a/drivers/s390/cio/device_ops.c
+++ b/drivers/s390/cio/device_ops.c
@@ -11,6 +11,7 @@
 #include <linux/list.h>
 #include <linux/device.h>
 #include <linux/delay.h>
+#include <linux/completion.h>
 
 #include <asm/ccwdev.h>
 #include <asm/idals.h>
@@ -504,74 +505,65 @@ __u8 ccw_device_get_path_mask(struct ccw_device *cdev)
         return sch->lpm;
 }
 
-/*
- * Try to break the lock on a boxed device.
- */
-int
-ccw_device_stlck(struct ccw_device *cdev)
-{
-        void *buf, *buf2;
-        unsigned long flags;
-        struct subchannel *sch;
-        int ret;
+struct stlck_data {
+        struct completion done;
+        int rc;
+};
 
-        if (!cdev)
-                return -ENODEV;
+void ccw_device_stlck_done(struct ccw_device *cdev, void *data, int rc)
+{
+        struct stlck_data *sdata = data;
 
-        if (cdev->drv && !cdev->private->options.force)
-                return -EINVAL;
+        sdata->rc = rc;
+        complete(&sdata->done);
+}
 
-        sch = to_subchannel(cdev->dev.parent);
-        
-        CIO_TRACE_EVENT(2, "stl lock");
-        CIO_TRACE_EVENT(2, dev_name(&cdev->dev));
+/*
+ * Perform unconditional reserve + release.
+ */
+int ccw_device_stlck(struct ccw_device *cdev)
+{
+        struct subchannel *sch = to_subchannel(cdev->dev.parent);
+        struct stlck_data data;
+        u8 *buffer;
+        int rc;
 
-        buf = kmalloc(32*sizeof(char), GFP_DMA|GFP_KERNEL);
-        if (!buf)
-                return -ENOMEM;
-        buf2 = kmalloc(32*sizeof(char), GFP_DMA|GFP_KERNEL);
-        if (!buf2) {
-                kfree(buf);
-                return -ENOMEM;
+        /* Check if steal lock operation is valid for this device. */
+        if (cdev->drv) {
+                if (!cdev->private->options.force)
+                        return -EINVAL;
         }
-        spin_lock_irqsave(sch->lock, flags);
-        ret = cio_enable_subchannel(sch, (u32)(addr_t)sch);
-        if (ret)
-                goto out_unlock;
-        /*
-         * Setup ccw. We chain an unconditional reserve and a release so we
-         * only break the lock.
-         */
-        cdev->private->iccws[0].cmd_code = CCW_CMD_STLCK;
-        cdev->private->iccws[0].cda = (__u32) __pa(buf);
-        cdev->private->iccws[0].count = 32;
-        cdev->private->iccws[0].flags = CCW_FLAG_CC;
-        cdev->private->iccws[1].cmd_code = CCW_CMD_RELEASE;
-        cdev->private->iccws[1].cda = (__u32) __pa(buf2);
-        cdev->private->iccws[1].count = 32;
-        cdev->private->iccws[1].flags = 0;
-        ret = cio_start(sch, cdev->private->iccws, 0);
-        if (ret) {
-                cio_disable_subchannel(sch); //FIXME: return code?
+        buffer = kzalloc(64, GFP_DMA | GFP_KERNEL);
+        if (!buffer)
+                return -ENOMEM;
+        init_completion(&data.done);
+        data.rc = -EIO;
+        spin_lock_irq(sch->lock);
+        rc = cio_enable_subchannel(sch, (u32) (addr_t) sch);
+        if (rc)
                 goto out_unlock;
+        /* Perform operation. */
+        cdev->private->state = DEV_STATE_STEAL_LOCK,
+        ccw_device_stlck_start(cdev, &data, &buffer[0], &buffer[32]);
+        spin_unlock_irq(sch->lock);
+        /* Wait for operation to finish. */
+        if (wait_for_completion_interruptible(&data.done)) {
+                /* Got a signal. */
+                spin_lock_irq(sch->lock);
+                ccw_request_cancel(cdev);
+                spin_unlock_irq(sch->lock);
+                wait_for_completion(&data.done);
         }
-        cdev->private->irb.scsw.cmd.actl |= SCSW_ACTL_START_PEND;
-        spin_unlock_irqrestore(sch->lock, flags);
-        wait_event(cdev->private->wait_q,
-                   cdev->private->irb.scsw.cmd.actl == 0);
-        spin_lock_irqsave(sch->lock, flags);
-        cio_disable_subchannel(sch); //FIXME: return code?
-        if ((cdev->private->irb.scsw.cmd.dstat !=
-             (DEV_STAT_CHN_END|DEV_STAT_DEV_END)) ||
-            (cdev->private->irb.scsw.cmd.cstat != 0))
-                ret = -EIO;
-        /* Clear irb. */
-        memset(&cdev->private->irb, 0, sizeof(struct irb));
+        rc = data.rc;
+        /* Check results. */
+        spin_lock_irq(sch->lock);
+        cio_disable_subchannel(sch);
+        cdev->private->state = DEV_STATE_BOXED;
 out_unlock:
-        kfree(buf);
-        kfree(buf2);
-        spin_unlock_irqrestore(sch->lock, flags);
-        return ret;
+        spin_unlock_irq(sch->lock);
+        kfree(buffer);
+
+        return rc;
 }
 
 void *ccw_device_get_chp_desc(struct ccw_device *cdev, int chp_no)
diff --git a/drivers/s390/cio/device_pgid.c b/drivers/s390/cio/device_pgid.c
index 4d54abd82b8c..5bcefeaff744 100644
--- a/drivers/s390/cio/device_pgid.c
+++ b/drivers/s390/cio/device_pgid.c
@@ -507,3 +507,55 @@ void ccw_device_disband_start(struct ccw_device *cdev)
         spid_build_cp(cdev, fn);
         ccw_request_start(cdev);
 }
+
+static void stlck_build_cp(struct ccw_device *cdev, void *buf1, void *buf2)
+{
+        struct ccw_request *req = &cdev->private->req;
+        struct ccw1 *cp = cdev->private->iccws;
+
+        cp[0].cmd_code = CCW_CMD_STLCK;
+        cp[0].cda = (u32) (addr_t) buf1;
+        cp[0].count = 32;
+        cp[0].flags = CCW_FLAG_CC;
+        cp[1].cmd_code = CCW_CMD_RELEASE;
+        cp[1].cda = (u32) (addr_t) buf2;
+        cp[1].count = 32;
+        cp[1].flags = 0;
+        req->cp = cp;
+}
+
+static void stlck_callback(struct ccw_device *cdev, void *data, int rc)
+{
+        ccw_device_stlck_done(cdev, data, rc);
+}
+
+/**
+ * ccw_device_stlck_start - perform unconditional release
+ * @cdev: ccw device
+ * @data: data pointer to be passed to ccw_device_stlck_done
+ * @buf1: data pointer used in channel program
+ * @buf2: data pointer used in channel program
+ *
+ * Execute a channel program on @cdev to release an existing PGID reservation.
+ * When finished, call ccw_device_stlck_done with a return code specifying the
+ * result.
+ */
+void ccw_device_stlck_start(struct ccw_device *cdev, void *data, void *buf1,
+                            void *buf2)
+{
+        struct subchannel *sch = to_subchannel(cdev->dev.parent);
+        struct ccw_request *req = &cdev->private->req;
+
+        CIO_TRACE_EVENT(4, "stlck");
+        CIO_HEX_EVENT(4, &cdev->private->dev_id, sizeof(cdev->private->dev_id));
+        /* Request setup. */
+        memset(req, 0, sizeof(*req));
+        req->timeout    = PGID_TIMEOUT;
+        req->maxretries = PGID_RETRIES;
+        req->lpm        = sch->schib.pmcw.pam & sch->opm;
+        req->data       = data;
+        req->callback   = stlck_callback;
+        stlck_build_cp(cdev, buf1, buf2);
+        ccw_request_start(cdev);
+}
+