On Tue, Jan 29, 2013 at 08:11:56AM +0100, Hannes Reinecke wrote:
> This patch implements generic block layer timeout handling
> callbacks for DASDs. When the timeout expires the respective
> cqr is aborted.
>
> With this timeout handler time-critical request abort
> is guaranteed as the abort does not depend on the internal
> state of the various DASD driver queues.
>
> Signed-off-by: Hannes Reinecke <h...@suse.de>
> Acked-by: Stefan Weinhuber <w...@de.ibm.com>
[...]
> +enum blk_eh_timer_return dasd_times_out(struct request *req)
> +{
> + struct dasd_ccw_req *cqr = req->completion_data;
> + struct dasd_block *block = req->q->queuedata;
> + struct dasd_device *device;
> + int rc = 0;
> +
> + if (!cqr)
> + return BLK_EH_NOT_HANDLED;
> +
> + device = cqr->startdev ? cqr->startdev : block->base;
> + DBF_DEV_EVENT(DBF_WARNING, device,
> + " dasd_times_out cqr %p status %x",
> + cqr, cqr->status);
> +
> + spin_lock(&block->queue_lock);
> + spin_lock(get_ccwdev_lock(device->cdev));
^^^
> + cqr->retries = -1;
> + cqr->intrc = -ETIMEDOUT;
> + if (cqr->status >= DASD_CQR_QUEUED) {
> + spin_unlock(get_ccwdev_lock(device->cdev));
> + 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;
> +
> + list_for_each_entry_safe(searchcqr, nextcqr,
> + &block->ccw_queue, blocklist) {
> + tmpcqr = searchcqr;
> + while (tmpcqr->refers)
> + tmpcqr = tmpcqr->refers;
> + if (tmpcqr != cqr)
> + continue;
> + /* searchcqr is an ERP request for cqr */
> + searchcqr->retries = -1;
> + searchcqr->intrc = -ETIMEDOUT;
> + if (searchcqr->status >= DASD_CQR_QUEUED) {
> + spin_lock(get_ccwdev_lock(device->cdev));
^^^
This looks like a potential dead lock.
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