PCI: OF: Fix I/O space page leak

When testing the R-Car PCIe driver on the Condor board, if the PCIe PHY
driver was left disabled, the kernel crashed with this BUG:

  kernel BUG at lib/ioremap.c:72!
  Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 0 PID: 39 Comm: kworker/0:1 Not tainted 4.17.0-dirty #1092
  Hardware name: Renesas Condor board based on r8a77980 (DT)
  Workqueue: events deferred_probe_work_func
  pstate: 80000005 (Nzcv daif -PAN -UAO)
  pc : ioremap_page_range+0x370/0x3c8
  lr : ioremap_page_range+0x40/0x3c8
  sp : ffff000008da39e0
  x29: ffff000008da39e0 x28: 00e8000000000f07
  x27: ffff7dfffee00000 x26: 0140000000000000
  x25: ffff7dfffef00000 x24: 00000000000fe100
  x23: ffff80007b906000 x22: ffff000008ab8000
  x21: ffff000008bb1d58 x20: ffff7dfffef00000
  x19: ffff800009c30fb8 x18: 0000000000000001
  x17: 00000000000152d0 x16: 00000000014012d0
  x15: 0000000000000000 x14: 0720072007200720
  x13: 0720072007200720 x12: 0720072007200720
  x11: 0720072007300730 x10: 00000000000000ae
  x9 : 0000000000000000 x8 : ffff7dffff000000
  x7 : 0000000000000000 x6 : 0000000000000100
  x5 : 0000000000000000 x4 : 000000007b906000
  x3 : ffff80007c61a880 x2 : ffff7dfffeefffff
  x1 : 0000000040000000 x0 : 00e80000fe100f07
  Process kworker/0:1 (pid: 39, stack limit = 0x        (ptrval))
  Call trace:
   ioremap_page_range+0x370/0x3c8
   pci_remap_iospace+0x7c/0xac
   pci_parse_request_of_pci_ranges+0x13c/0x190
   rcar_pcie_probe+0x4c/0xb04
   platform_drv_probe+0x50/0xbc
   driver_probe_device+0x21c/0x308
   __device_attach_driver+0x98/0xc8
   bus_for_each_drv+0x54/0x94
   __device_attach+0xc4/0x12c
   device_initial_probe+0x10/0x18
   bus_probe_device+0x90/0x98
   deferred_probe_work_func+0xb0/0x150
   process_one_work+0x12c/0x29c
   worker_thread+0x200/0x3fc
   kthread+0x108/0x134
   ret_from_fork+0x10/0x18
  Code: f9004ba2 54000080 aa0003fb 17ffff48 (d4210000)

It turned out that pci_remap_iospace() wasn't undone when the driver's
probe failed, and since devm_phy_optional_get() returned -EPROBE_DEFER,
the probe was retried, finally causing the BUG due to trying to remap
already remapped pages.

Introduce the devm_pci_remap_iospace() managed API and replace the
pci_remap_iospace() call with it to fix the bug.

Fixes: dbf9826d5797 ("PCI: generic: Convert to DT resource parsing API")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
[lorenzo.pieralisi@arm.com: split commit/updated the commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pci/of.c

@@ -612,7 +612,7 @@ int pci_parse_request_of_pci_ranges(struct device *dev,
 
 		switch (resource_type(res)) {
 		case IORESOURCE_IO:
-			err = pci_remap_iospace(res, iobase);
+			err = devm_pci_remap_iospace(dev, res, iobase);
 			if (err) {
 				dev_warn(dev, "error %d: failed to map resource %pR\n",
 					 err, res);

drivers/pci/pci.c

@@ -3579,6 +3579,44 @@ void pci_unmap_iospace(struct resource *res)
 }
 EXPORT_SYMBOL(pci_unmap_iospace);
 
+static void devm_pci_unmap_iospace(struct device *dev, void *ptr)
+{
+	struct resource **res = ptr;
+
+	pci_unmap_iospace(*res);
+}
+
+/**
+ * devm_pci_remap_iospace - Managed pci_remap_iospace()
+ * @dev: Generic device to remap IO address for
+ * @res: Resource describing the I/O space
+ * @phys_addr: physical address of range to be mapped
+ *
+ * Managed pci_remap_iospace().  Map is automatically unmapped on driver
+ * detach.
+ */
+int devm_pci_remap_iospace(struct device *dev, const struct resource *res,
+			   phys_addr_t phys_addr)
+{
+	const struct resource **ptr;
+	int error;
+
+	ptr = devres_alloc(devm_pci_unmap_iospace, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	error = pci_remap_iospace(res, phys_addr);
+	if (error) {
+		devres_free(ptr);
+	} else	{
+		*ptr = res;
+		devres_add(dev, ptr);
+	}
+
+	return error;
+}
+EXPORT_SYMBOL(devm_pci_remap_iospace);
+
 /**
  * devm_pci_remap_cfgspace - Managed pci_remap_cfgspace()
  * @dev: Generic device to remap IO address for

include/linux/pci.h

@@ -1240,6 +1240,8 @@ int pci_register_io_range(struct fwnode_handle *fwnode, phys_addr_t addr,
 unsigned long pci_address_to_pio(phys_addr_t addr);
 phys_addr_t pci_pio_to_address(unsigned long pio);
 int pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr);
+int devm_pci_remap_iospace(struct device *dev, const struct resource *res,
+			   phys_addr_t phys_addr);
 void pci_unmap_iospace(struct resource *res);
 void __iomem *devm_pci_remap_cfgspace(struct device *dev,
 				      resource_size_t offset,