Patch "s390/qdio: handle deferred cc1" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    s390/qdio: handle deferred cc1

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     s390-qdio-handle-deferred-cc1.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 6943b6e9ad82a38b3a1dc5eb204e41a1170eb961
Author: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
Date:   Wed Apr 10 11:46:18 2024 +0200

    s390/qdio: handle deferred cc1
    
    [ Upstream commit 607638faf2ff1cede37458111496e7cc6c977f6f ]
    
    A deferred condition code 1 response indicates that I/O was not started
    and should be retried. The current QDIO implementation handles a cc1
    response as I/O error, resulting in a failed QDIO setup. This can happen
    for example when a path verification request arrives at the same time
    as QDIO setup I/O is started.
    
    Fix this by retrying the QDIO setup I/O when a cc1 response is received.
    
    Note that since
    
    commit 2297791c92d0 ("s390/cio: dont unregister subchannel from child-drivers")
    commit 5ef1dc40ffa6 ("s390/cio: fix invalid -EBUSY on ccw_device_start")
    
    deferred cc1 responses are much more likely to occur. See the commit
    message of the latter for more background information.
    
    Fixes: 2297791c92d0 ("s390/cio: dont unregister subchannel from child-drivers")
    Reviewed-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
    Signed-off-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
    Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 9cde55730b65a..ebcb535809882 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -722,8 +722,8 @@ static void qdio_handle_activate_check(struct qdio_irq *irq_ptr,
 	lgr_info_log();
 }
 
-static void qdio_establish_handle_irq(struct qdio_irq *irq_ptr, int cstat,
-				      int dstat)
+static int qdio_establish_handle_irq(struct qdio_irq *irq_ptr, int cstat,
+				     int dstat, int dcc)
 {
 	DBF_DEV_EVENT(DBF_INFO, irq_ptr, "qest irq");
 
@@ -731,15 +731,18 @@ static void qdio_establish_handle_irq(struct qdio_irq *irq_ptr, int cstat,
 		goto error;
 	if (dstat & ~(DEV_STAT_DEV_END | DEV_STAT_CHN_END))
 		goto error;
+	if (dcc == 1)
+		return -EAGAIN;
 	if (!(dstat & DEV_STAT_DEV_END))
 		goto error;
 	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_ESTABLISHED);
-	return;
+	return 0;
 
 error:
 	DBF_ERROR("%4x EQ:error", irq_ptr->schid.sch_no);
 	DBF_ERROR("ds: %2x cs:%2x", dstat, cstat);
 	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_ERR);
+	return -EIO;
 }
 
 /* qdio interrupt handler */
@@ -748,7 +751,7 @@ void qdio_int_handler(struct ccw_device *cdev, unsigned long intparm,
 {
 	struct qdio_irq *irq_ptr = cdev->private->qdio_data;
 	struct subchannel_id schid;
-	int cstat, dstat;
+	int cstat, dstat, rc, dcc;
 
 	if (!intparm || !irq_ptr) {
 		ccw_device_get_schid(cdev, &schid);
@@ -768,10 +771,12 @@ void qdio_int_handler(struct ccw_device *cdev, unsigned long intparm,
 	qdio_irq_check_sense(irq_ptr, irb);
 	cstat = irb->scsw.cmd.cstat;
 	dstat = irb->scsw.cmd.dstat;
+	dcc   = scsw_cmd_is_valid_cc(&irb->scsw) ? irb->scsw.cmd.cc : 0;
+	rc    = 0;
 
 	switch (irq_ptr->state) {
 	case QDIO_IRQ_STATE_INACTIVE:
-		qdio_establish_handle_irq(irq_ptr, cstat, dstat);
+		rc = qdio_establish_handle_irq(irq_ptr, cstat, dstat, dcc);
 		break;
 	case QDIO_IRQ_STATE_CLEANUP:
 		qdio_set_state(irq_ptr, QDIO_IRQ_STATE_INACTIVE);
@@ -785,12 +790,25 @@ void qdio_int_handler(struct ccw_device *cdev, unsigned long intparm,
 		if (cstat || dstat)
 			qdio_handle_activate_check(irq_ptr, intparm, cstat,
 						   dstat);
+		else if (dcc == 1)
+			rc = -EAGAIN;
 		break;
 	case QDIO_IRQ_STATE_STOPPED:
 		break;
 	default:
 		WARN_ON_ONCE(1);
 	}
+
+	if (rc == -EAGAIN) {
+		DBF_DEV_EVENT(DBF_INFO, irq_ptr, "qint retry");
+		rc = ccw_device_start(cdev, irq_ptr->ccw, intparm, 0, 0);
+		if (!rc)
+			return;
+		DBF_ERROR("%4x RETRY ERR", irq_ptr->schid.sch_no);
+		DBF_ERROR("rc:%4x", rc);
+		qdio_set_state(irq_ptr, QDIO_IRQ_STATE_ERR);
+	}
+
 	wake_up(&cdev->private->wait_q);
 }