From: Sebastian Ott <sebott@linux.vnet.ibm.com>
Subject: s390/pci: improve error handling during fmb (de)registration
Patch-mainline: v4.13-rc1
Git-commit: 4e5bd7803bd1e822513d1007bad1527a2ec589b6
References: bnc#1066983, LTC#157731

Description:  PCI: fix hotplug related issues
Symptom:      After serveral cycles of hot-unplug/hotplug the affected
              function stops working or the kernel oopses.
Problem:      Hotplug notifications happen after the fact, meaning it's
              not possible to issue instructions to the function for
              cleanup purposes. Thus we never release the associated
              resources and at some point fail to allocate new ones.
Solution:     During clean up treat some errors as success (e.g. a
              function that's gone can't create an interrupt).
Reproduction: vmcp att pcif XXX to \* ;vmcp det pcif XXX #in a loop

Upstream-Description:

              s390/pci: improve error handling during fmb (de)registration

              Cleanup in zpci_fmb_enable_device when fmb registration fails. Also
              don't free the fmb when deregistration fails in zpci_fmb_disable_device
              but handle error situations when a function was hot-unplugged.

              Also remove the mod_pci helper since it is no longer used.

              Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
              Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
              Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>


Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 arch/s390/pci/pci.c |   51 +++++++++++++++++++++------------------------------
 1 file changed, 21 insertions(+), 30 deletions(-)

--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -136,27 +136,6 @@ static int zpci_clear_airq(struct zpci_d
 	return cc ? -EIO : 0;
 }
 
-struct mod_pci_args {
-	u64 base;
-	u64 limit;
-	u64 iota;
-	u64 fmb_addr;
-};
-
-static int mod_pci(struct zpci_dev *zdev, int fn, u8 dmaas, struct mod_pci_args *args)
-{
-	u64 req = ZPCI_CREATE_REQ(zdev->fh, dmaas, fn);
-	struct zpci_fib fib = {0};
-	u8 status;
-
-	fib.pba = args->base;
-	fib.pal = args->limit;
-	fib.iota = args->iota;
-	fib.fmb_addr = args->fmb_addr;
-
-	return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;
-}
-
 /* Modify PCI: Register I/O address translation parameters */
 int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas,
 		       u64 base, u64 limit, u64 iota)
@@ -188,7 +167,9 @@ int zpci_unregister_ioat(struct zpci_dev
 /* Modify PCI: Set PCI function measurement parameters */
 int zpci_fmb_enable_device(struct zpci_dev *zdev)
 {
-	struct mod_pci_args args = { 0, 0, 0, 0 };
+	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_SET_MEASURE);
+	struct zpci_fib fib = {0};
+	u8 cc, status;
 
 	if (zdev->fmb || sizeof(*zdev->fmb) < zdev->fmb_length)
 		return -EINVAL;
@@ -203,25 +184,35 @@ int zpci_fmb_enable_device(struct zpci_d
 	atomic64_set(&zdev->mapped_pages, 0);
 	atomic64_set(&zdev->unmapped_pages, 0);
 
-	args.fmb_addr = virt_to_phys(zdev->fmb);
-	return mod_pci(zdev, ZPCI_MOD_FC_SET_MEASURE, 0, &args);
+	fib.fmb_addr = virt_to_phys(zdev->fmb);
+	cc = zpci_mod_fc(req, &fib, &status);
+	if (cc) {
+		kmem_cache_free(zdev_fmb_cache, zdev->fmb);
+		zdev->fmb = NULL;
+	}
+	return cc ? -EIO : 0;
 }
 
 /* Modify PCI: Disable PCI function measurement */
 int zpci_fmb_disable_device(struct zpci_dev *zdev)
 {
-	struct mod_pci_args args = { 0, 0, 0, 0 };
-	int rc;
+	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_SET_MEASURE);
+	struct zpci_fib fib = {0};
+	u8 cc, status;
 
 	if (!zdev->fmb)
 		return -EINVAL;
 
 	/* Function measurement is disabled if fmb address is zero */
-	rc = mod_pci(zdev, ZPCI_MOD_FC_SET_MEASURE, 0, &args);
+	cc = zpci_mod_fc(req, &fib, &status);
+	if (cc == 3) /* Function already gone. */
+		cc = 0;
 
-	kmem_cache_free(zdev_fmb_cache, zdev->fmb);
-	zdev->fmb = NULL;
-	return rc;
+	if (!cc) {
+		kmem_cache_free(zdev_fmb_cache, zdev->fmb);
+		zdev->fmb = NULL;
+	}
+	return cc ? -EIO : 0;
 }
 
 static int zpci_cfg_load(struct zpci_dev *zdev, int offset, u32 *val, u8 len)