[PATCH] virtio_mmio: fix devm cleanup

[Mark Rutland <mark.rutland@arm.com>]

Recent rework of the virtio_mmio probe path balanced a devm_ioremap()
with an iounmap() rather than its devm variant. This ends up corrupting
the devm datastructures, and results in the following boot failure on
arm64 under QEMU 2.9.0:

[    3.450397] ------------[ cut here ]------------
[    3.453822] Trying to vfree() nonexistent vm area (00000000c05b4844)
[    3.460534] WARNING: CPU: 1 PID: 1 at mm/vmalloc.c:1525 __vunmap+0x1b8/0x220
[    3.475898] Kernel panic - not syncing: panic_on_warn set ...
[    3.475898]
[    3.493933] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.15.0-rc3 #1
[    3.513109] Hardware name: linux,dummy-virt (DT)
[    3.525382] Call trace:
[    3.531683]  dump_backtrace+0x0/0x368
[    3.543921]  show_stack+0x20/0x30
[    3.547767]  dump_stack+0x108/0x164
[    3.559584]  panic+0x25c/0x51c
[    3.569184]  __warn+0x29c/0x31c
[    3.576023]  report_bug+0x1d4/0x290
[    3.586069]  bug_handler.part.2+0x40/0x100
[    3.597820]  bug_handler+0x4c/0x88
[    3.608400]  brk_handler+0x11c/0x218
[    3.613430]  do_debug_exception+0xe8/0x318
[    3.627370]  el1_dbg+0x18/0x78
[    3.634037]  __vunmap+0x1b8/0x220
[    3.648747]  vunmap+0x6c/0xc0
[    3.653864]  __iounmap+0x44/0x58
[    3.659771]  devm_ioremap_release+0x34/0x68
[    3.672983]  release_nodes+0x404/0x880
[    3.683543]  devres_release_all+0x6c/0xe8
[    3.695692]  driver_probe_device+0x250/0x828
[    3.706187]  __driver_attach+0x190/0x210
[    3.717645]  bus_for_each_dev+0x14c/0x1f0
[    3.728633]  driver_attach+0x48/0x78
[    3.740249]  bus_add_driver+0x26c/0x5b8
[    3.752248]  driver_register+0x16c/0x398
[    3.757211]  __platform_driver_register+0xd8/0x128
[    3.770860]  virtio_mmio_init+0x1c/0x24
[    3.782671]  do_one_initcall+0xe0/0x398
[    3.791890]  kernel_init_freeable+0x594/0x660
[    3.798514]  kernel_init+0x18/0x190
[    3.810220]  ret_from_fork+0x10/0x18

To fix this, we can simply rip out the explicit cleanup that the devm
infrastructure will do for us when our probe function returns an error
code. We only need to ensure that we call put_device() if a call to
register_virtio_device() fails.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 7eb781b1bbb7136f ("virtio_mmio: add cleanup for virtio_mmio_probe")
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: weiping zhang <zhangweiping@didichuxing.com>
Cc: virtualization@lists.linux-foundation.org
---
 drivers/virtio/virtio_mmio.c | 36 +++++++++---------------------------
 1 file changed, 9 insertions(+), 27 deletions(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index a9192fe4f345..793b1085967f 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -522,10 +522,8 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 		return -EBUSY;
 
 	vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
-	if (!vm_dev) {
-		rc = -ENOMEM;
-		goto free_mem;
-	}
+	if (!vm_dev)
+		return -ENOMEM;
 
 	vm_dev->vdev.dev.parent = &pdev->dev;
 	vm_dev->vdev.dev.release = virtio_mmio_release_dev;
@@ -535,17 +533,14 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	spin_lock_init(&vm_dev->lock);
 
 	vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
-	if (vm_dev->base == NULL) {
-		rc = -EFAULT;
-		goto free_vmdev;
-	}
+	if (vm_dev->base == NULL)
+		return -EFAULT;
 
 	/* Check magic value */
 	magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
 	if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
 		dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
-		rc = -ENODEV;
-		goto unmap;
+		return -ENODEV;
 	}
 
 	/* Check device version */
@@ -553,8 +548,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	if (vm_dev->version < 1 || vm_dev->version > 2) {
 		dev_err(&pdev->dev, "Version %ld not supported!\n",
 				vm_dev->version);
-		rc = -ENXIO;
-		goto unmap;
+		return -ENXIO;
 	}
 
 	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
@@ -563,8 +557,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
 		 * with no function. End probing now with no error reported.
 		 */
-		rc = -ENODEV;
-		goto unmap;
+		return -ENODEV;
 	}
 	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 
@@ -590,20 +583,9 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, vm_dev);
 
 	rc = register_virtio_device(&vm_dev->vdev);
-	if (rc) {
-		iounmap(vm_dev->base);
-		devm_release_mem_region(&pdev->dev, mem->start,
-					resource_size(mem));
+	if (rc)
 		put_device(&vm_dev->vdev.dev);
-	}
-	return rc;
-unmap:
-	iounmap(vm_dev->base);
-free_mem:
-	devm_release_mem_region(&pdev->dev, mem->start,
-			resource_size(mem));
-free_vmdev:
-	devm_kfree(&pdev->dev, vm_dev);
+
 	return rc;
 }
 
-- 
2.11.0