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[S390] cio: subchannel evaluation function operates without lock
css_evaluate_subchannel() operates subchannel without lock which can lead to erratic behavior caused by concurrent device access. Also split evaluation function to make it more readable. Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Peter Oberparleiter
Martin Schwidefsky
parent
28bdc6f623
commit
564337f34c
@ -182,136 +182,141 @@ get_subchannel_by_schid(struct subchannel_id schid)
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return dev ? to_subchannel(dev) : NULL;
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}
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static inline int
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css_get_subchannel_status(struct subchannel *sch, struct subchannel_id schid)
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static inline int css_get_subchannel_status(struct subchannel *sch)
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{
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struct schib schib;
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int cc;
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cc = stsch(schid, &schib);
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if (cc)
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if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
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return CIO_GONE;
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if (!schib.pmcw.dnv)
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return CIO_GONE;
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if (sch && sch->schib.pmcw.dnv &&
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(schib.pmcw.dev != sch->schib.pmcw.dev))
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if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
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return CIO_REVALIDATE;
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if (sch && !sch->lpm)
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if (!sch->lpm)
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return CIO_NO_PATH;
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return CIO_OPER;
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}
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static int
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css_evaluate_subchannel(struct subchannel_id schid, int slow)
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static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
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{
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int event, ret, disc;
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struct subchannel *sch;
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unsigned long flags;
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enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
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sch = get_subchannel_by_schid(schid);
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disc = sch ? device_is_disconnected(sch) : 0;
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spin_lock_irqsave(&sch->lock, flags);
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disc = device_is_disconnected(sch);
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if (disc && slow) {
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if (sch)
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put_device(&sch->dev);
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return 0; /* Already processed. */
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/* Disconnected devices are evaluated directly only.*/
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spin_unlock_irqrestore(&sch->lock, flags);
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return 0;
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}
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/*
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* We've got a machine check, so running I/O won't get an interrupt.
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* Kill any pending timers.
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*/
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if (sch)
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device_kill_pending_timer(sch);
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/* No interrupt after machine check - kill pending timers. */
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device_kill_pending_timer(sch);
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if (!disc && !slow) {
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if (sch)
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put_device(&sch->dev);
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return -EAGAIN; /* Will be done on the slow path. */
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/* Non-disconnected devices are evaluated on the slow path. */
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spin_unlock_irqrestore(&sch->lock, flags);
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return -EAGAIN;
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}
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event = css_get_subchannel_status(sch, schid);
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event = css_get_subchannel_status(sch);
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CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
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schid.ssid, schid.sch_no, event,
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sch?(disc?"disconnected":"normal"):"unknown",
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slow?"slow":"fast");
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sch->schid.ssid, sch->schid.sch_no, event,
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disc ? "disconnected" : "normal",
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slow ? "slow" : "fast");
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/* Analyze subchannel status. */
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action = NONE;
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switch (event) {
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case CIO_NO_PATH:
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if (disc) {
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/* Check if paths have become available. */
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action = REPROBE;
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break;
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}
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/* fall through */
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case CIO_GONE:
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if (!sch) {
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/* Never used this subchannel. Ignore. */
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ret = 0;
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break;
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}
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if (disc && (event == CIO_NO_PATH)) {
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/*
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* Uargh, hack again. Because we don't get a machine
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* check on configure on, our path bookkeeping can
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* be out of date here (it's fine while we only do
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* logical varying or get chsc machine checks). We
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* need to force reprobing or we might miss devices
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* coming operational again. It won't do harm in real
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* no path situations.
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*/
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spin_lock_irqsave(&sch->lock, flags);
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device_trigger_reprobe(sch);
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spin_unlock_irqrestore(&sch->lock, flags);
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ret = 0;
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break;
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}
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if (sch->driver && sch->driver->notify &&
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sch->driver->notify(&sch->dev, event)) {
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cio_disable_subchannel(sch);
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device_set_disconnected(sch);
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ret = 0;
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break;
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}
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/*
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* Unregister subchannel.
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* The device will be killed automatically.
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*/
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/* Prevent unwanted effects when opening lock. */
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cio_disable_subchannel(sch);
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device_set_disconnected(sch);
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/* Ask driver what to do with device. */
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action = UNREGISTER;
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if (sch->driver && sch->driver->notify) {
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spin_unlock_irqrestore(&sch->lock, flags);
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ret = sch->driver->notify(&sch->dev, event);
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spin_lock_irqsave(&sch->lock, flags);
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if (ret)
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action = NONE;
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}
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break;
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case CIO_REVALIDATE:
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/* Device will be removed, so no notify necessary. */
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if (disc)
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/* Reprobe because immediate unregister might block. */
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action = REPROBE;
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else
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action = UNREGISTER_PROBE;
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break;
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case CIO_OPER:
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if (disc)
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/* Get device operational again. */
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action = REPROBE;
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break;
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}
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/* Perform action. */
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ret = 0;
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switch (action) {
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case UNREGISTER:
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case UNREGISTER_PROBE:
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/* Unregister device (will use subchannel lock). */
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spin_unlock_irqrestore(&sch->lock, flags);
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css_sch_device_unregister(sch);
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spin_lock_irqsave(&sch->lock, flags);
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/* Reset intparm to zeroes. */
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sch->schib.pmcw.intparm = 0;
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cio_modify(sch);
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put_device(&sch->dev);
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ret = 0;
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/* Probe if necessary. */
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if (action == UNREGISTER_PROBE)
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ret = css_probe_device(sch->schid);
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break;
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case CIO_REVALIDATE:
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/*
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* Revalidation machine check. Sick.
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* We don't notify the driver since we have to throw the device
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* away in any case.
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*/
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if (!disc) {
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css_sch_device_unregister(sch);
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/* Reset intparm to zeroes. */
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sch->schib.pmcw.intparm = 0;
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cio_modify(sch);
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put_device(&sch->dev);
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ret = css_probe_device(schid);
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} else {
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/*
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* We can't immediately deregister the disconnected
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* device since it might block.
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*/
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spin_lock_irqsave(&sch->lock, flags);
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device_trigger_reprobe(sch);
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spin_unlock_irqrestore(&sch->lock, flags);
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ret = 0;
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}
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break;
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case CIO_OPER:
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if (disc) {
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spin_lock_irqsave(&sch->lock, flags);
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/* Get device operational again. */
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device_trigger_reprobe(sch);
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spin_unlock_irqrestore(&sch->lock, flags);
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}
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ret = sch ? 0 : css_probe_device(schid);
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case REPROBE:
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device_trigger_reprobe(sch);
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break;
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default:
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BUG();
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ret = 0;
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break;
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}
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spin_unlock_irqrestore(&sch->lock, flags);
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return ret;
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}
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static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
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{
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struct schib schib;
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if (!slow) {
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/* Will be done on the slow path. */
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return -EAGAIN;
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}
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if (stsch(schid, &schib) || !schib.pmcw.dnv) {
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/* Unusable - ignore. */
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return 0;
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}
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CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
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"slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
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return css_probe_device(schid);
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}
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static int css_evaluate_subchannel(struct subchannel_id schid, int slow)
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{
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struct subchannel *sch;
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int ret;
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sch = get_subchannel_by_schid(schid);
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if (sch) {
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ret = css_evaluate_known_subchannel(sch, slow);
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put_device(&sch->dev);
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} else
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ret = css_evaluate_new_subchannel(schid, slow);
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return ret;
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}
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