From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date: Sat, 1 Feb 2014 14:38:29 +0000 (+0100)
Subject: Revert "PCI: Remove from bus_list and release resources in pci_release_dev()"
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=04480094de7242d08bb62088e713fd7fe00443b4;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

Revert "PCI: Remove from bus_list and release resources in pci_release_dev()"

Revert commit ef83b0781a73 "PCI: Remove from bus_list and release
resources in pci_release_dev()" that made some nasty race conditions
become possible.  For example, if a Thunderbolt link is unplugged
and then replugged immediately, the pci_release_dev() resulting from
the hot-remove code path may be racing with the hot-add code path
which after that commit causes various kinds of breakage to happen
(up to and including a hard crash of the whole system).

Moreover, the problem that commit ef83b0781a73 attempted to address
cannot happen any more after commit 8a4c5c329de7 "PCI: Check parent
kobject in pci_destroy_dev()", because pci_destroy_dev() will now
return immediately if it has already been executed for the given
device.

Note, however, that the invocation of msi_remove_pci_irq_vectors()
removed by commit ef83b0781a73 from pci_free_resources() along with
the other changes made by it is not added back because of subsequent
code changes depending on that modification.

Fixes: ef83b0781a73 (PCI: Remove from bus_list and release resources in pci_release_dev())
Reported-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 04796c056d12..6e34498ec9f0 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1208,18 +1208,6 @@ static void pci_release_capabilities(struct pci_dev *dev)
 	pci_free_cap_save_buffers(dev);
 }
 
-static void pci_free_resources(struct pci_dev *dev)
-{
-	int i;
-
-	pci_cleanup_rom(dev);
-	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
-		struct resource *res = dev->resource + i;
-		if (res->parent)
-			release_resource(res);
-	}
-}
-
 /**
  * pci_release_dev - free a pci device structure when all users of it are finished.
  * @dev: device that's been disconnected
@@ -1229,14 +1217,9 @@ static void pci_free_resources(struct pci_dev *dev)
  */
 static void pci_release_dev(struct device *dev)
 {
-	struct pci_dev *pci_dev = to_pci_dev(dev);
-
-	down_write(&pci_bus_sem);
-	list_del(&pci_dev->bus_list);
-	up_write(&pci_bus_sem);
-
-	pci_free_resources(pci_dev);
+	struct pci_dev *pci_dev;
 
+	pci_dev = to_pci_dev(dev);
 	pci_release_capabilities(pci_dev);
 	pci_release_of_node(pci_dev);
 	pcibios_release_device(pci_dev);
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 4ff36bfa785e..8bd76c9ba21c 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -3,6 +3,18 @@
 #include <linux/pci-aspm.h>
 #include "pci.h"
 
+static void pci_free_resources(struct pci_dev *dev)
+{
+	int i;
+
+	pci_cleanup_rom(dev);
+	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
+		struct resource *res = dev->resource + i;
+		if (res->parent)
+			release_resource(res);
+	}
+}
+
 static void pci_stop_dev(struct pci_dev *dev)
 {
 	pci_pme_active(dev, false);
@@ -25,6 +37,11 @@ static void pci_destroy_dev(struct pci_dev *dev)
 
 	device_del(&dev->dev);
 
+	down_write(&pci_bus_sem);
+	list_del(&dev->bus_list);
+	up_write(&pci_bus_sem);
+
+	pci_free_resources(dev);
 	put_device(&dev->dev);
 }