firewire: Switch cdev code over to use register_chrdev and keep a list of devices.

The old mechanism kept a struct cdev for each fw device, but fops->release
would reference this struct after the device got freed in some cases.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 36 insertions, 20 deletions

diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index ccc05e511a4f..b24090ae9c70 100644
--- a/drivers/firewire/fw-device.c
+++ b/drivers/firewire/fw-device.c
@@ -25,6 +25,7 @@
 #include <linux/kthread.h>
 #include <linux/device.h>
 #include <linux/delay.h>
+#include <linux/idr.h>
 #include "fw-transaction.h"
 #include "fw-topology.h"
 #include "fw-device.h"
@@ -407,14 +408,31 @@ static int shutdown_unit(struct device *device, void *data)
         return 0;
 }
 
+static DEFINE_IDR(fw_device_idr);
+int fw_cdev_major;
+
+struct fw_device *fw_device_from_devt(dev_t devt)
+{
+        struct fw_device *device;
+
+        down_read(&fw_bus_type.subsys.rwsem);
+        device = idr_find(&fw_device_idr, MINOR(devt));
+        up_read(&fw_bus_type.subsys.rwsem);
+
+        return device;
+}
+
 static void fw_device_shutdown(struct work_struct *work)
 {
         struct fw_device *device =
                 container_of(work, struct fw_device, work.work);
+        int minor = MINOR(device->device.devt);
+
+        down_write(&fw_bus_type.subsys.rwsem);
+        idr_remove(&fw_device_idr, minor);
+        up_write(&fw_bus_type.subsys.rwsem);
 
         device_remove_file(&device->device, &config_rom_attribute);
-        cdev_del(&device->cdev);
-        unregister_chrdev_region(device->device.devt, 1);
         device_for_each_child(&device->device, NULL, shutdown_unit);
         device_unregister(&device->device);
 }
@@ -434,9 +452,9 @@ static void fw_device_shutdown(struct work_struct *work)
 
 static void fw_device_init(struct work_struct *work)
 {
-        static atomic_t serial = ATOMIC_INIT(-1);
         struct fw_device *device =
                 container_of(work, struct fw_device, work.work);
+        int minor, err;
 
         /* All failure paths here set node->data to NULL, so that we
          * don't try to do device_for_each_child() on a kfree()'d
@@ -456,28 +474,24 @@ static void fw_device_init(struct work_struct *work)
                 return;
         }
 
+        err = -ENOMEM;
+        down_write(&fw_bus_type.subsys.rwsem);
+        if (idr_pre_get(&fw_device_idr, GFP_KERNEL))
+                err = idr_get_new(&fw_device_idr, device, &minor);
+        up_write(&fw_bus_type.subsys.rwsem);
+        if (err < 0)
+                goto error;
+
         device->device.bus = &fw_bus_type;
         device->device.release = fw_device_release;
         device->device.parent = device->card->device;
+        device->device.devt = MKDEV(fw_cdev_major, minor);
         snprintf(device->device.bus_id, sizeof device->device.bus_id,
-                 "fw%d", atomic_inc_return(&serial));
-
-        if (alloc_chrdev_region(&device->device.devt, 0, 1, "fw")) {
-                fw_error("Failed to register char device region.\n");
-                goto error;
-        }
-
-        cdev_init(&device->cdev, &fw_device_ops);
-        device->cdev.owner = THIS_MODULE;
-        kobject_set_name(&device->cdev.kobj, device->device.bus_id);
-        if (cdev_add(&device->cdev, device->device.devt, 1)) {
-                fw_error("Failed to register char device.\n");
-                goto error;
-        }
+                 "fw%d", minor);
 
         if (device_add(&device->device)) {
                 fw_error("Failed to add device.\n");
-                goto error;
+                goto error_with_cdev;
         }
 
         if (device_create_file(&device->device, &config_rom_attribute) < 0) {
@@ -513,9 +527,11 @@ static void fw_device_init(struct work_struct *work)
 
  error_with_device:
         device_del(&device->device);
+ error_with_cdev:
+        down_write(&fw_bus_type.subsys.rwsem);
+        idr_remove(&fw_device_idr, minor);
+        up_write(&fw_bus_type.subsys.rwsem);
  error:
-        cdev_del(&device->cdev);
-        unregister_chrdev_region(device->device.devt, 1);
         put_device(&device->device);
 }