Merge branch 'next' (accumulated 3.16 merge window patches) into master

Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.

* accumulated work in next: (6809 commits)
  ufs: sb mutex merge + mutex_destroy
  powerpc: update comments for generic idle conversion
  cris: update comments for generic idle conversion
  idle: remove cpu_idle() forward declarations
  nbd: zero from and len fields in NBD_CMD_DISCONNECT.
  mm: convert some level-less printks to pr_*
  MAINTAINERS: adi-buildroot-devel is moderated
  MAINTAINERS: add linux-api for review of API/ABI changes
  mm/kmemleak-test.c: use pr_fmt for logging
  fs/dlm/debug_fs.c: replace seq_printf by seq_puts
  fs/dlm/lockspace.c: convert simple_str to kstr
  fs/dlm/config.c: convert simple_str to kstr
  mm: mark remap_file_pages() syscall as deprecated
  mm: memcontrol: remove unnecessary memcg argument from soft limit functions
  mm: memcontrol: clean up memcg zoneinfo lookup
  mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
  mm/mempool.c: update the kmemleak stack trace for mempool allocations
  lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
  mm: introduce kmemleak_update_trace()
  mm/kmemleak.c: use %u to print ->checksum
  ...

1 files changed, 20 insertions, 5 deletions

diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 62fcd485f0a..d57a173685f 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -242,6 +242,15 @@ struct pci_dev *pcistub_get_pci_dev(struct xen_pcibk_device *pdev,
 	return found_dev;
 }
 
+/*
+ * Called when:
+ *  - XenBus state has been reconfigure (pci unplug). See xen_pcibk_remove_device
+ *  - XenBus state has been disconnected (guest shutdown). See xen_pcibk_xenbus_remove
+ *  - 'echo BDF > unbind' on pciback module with no guest attached. See pcistub_remove
+ *  - 'echo BDF > unbind' with a guest still using it. See pcistub_remove
+ *
+ *  As such we have to be careful.
+ */
 void pcistub_put_pci_dev(struct pci_dev *dev)
 {
 	struct pcistub_device *psdev, *found_psdev = NULL;
@@ -272,16 +281,16 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
 	 * and want to inhibit the user from fiddling with 'reset'
 	 */
 	pci_reset_function(dev);
-	pci_restore_state(psdev->dev);
+	pci_restore_state(dev);
 
 	/* This disables the device. */
-	xen_pcibk_reset_device(found_psdev->dev);
+	xen_pcibk_reset_device(dev);
 
 	/* And cleanup up our emulated fields. */
-	xen_pcibk_config_free_dyn_fields(found_psdev->dev);
-	xen_pcibk_config_reset_dev(found_psdev->dev);
+	xen_pcibk_config_reset_dev(dev);
+	xen_pcibk_config_free_dyn_fields(dev);
 
-	xen_unregister_device_domain_owner(found_psdev->dev);
+	xen_unregister_device_domain_owner(dev);
 
 	spin_lock_irqsave(&found_psdev->lock, flags);
 	found_psdev->pdev = NULL;
@@ -493,6 +502,8 @@ static int pcistub_seize(struct pci_dev *dev)
 	return err;
 }
 
+/* Called when 'bind'. This means we must _NOT_ call pci_reset_function or
+ * other functions that take the sysfs lock. */
 static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
 	int err = 0;
@@ -520,6 +531,8 @@ out:
 	return err;
 }
 
+/* Called when 'unbind'. This means we must _NOT_ call pci_reset_function or
+ * other functions that take the sysfs lock. */
 static void pcistub_remove(struct pci_dev *dev)
 {
 	struct pcistub_device *psdev, *found_psdev = NULL;
@@ -551,6 +564,8 @@ static void pcistub_remove(struct pci_dev *dev)
 			pr_warn("****** shutdown driver domain before binding device\n");
 			pr_warn("****** to other drivers or domains\n");
 
+			/* N.B. This ends up calling pcistub_put_pci_dev which ends up
+			 * doing the FLR. */
 			xen_pcibk_release_pci_dev(found_psdev->pdev,
 						found_psdev->dev);
 		}