Protect tpm_chip_list when transversing it.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index dfd4e7f..4f18f84 100644 (file)
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -961,33 +961,28 @@ EXPORT_SYMBOL_GPL(tpm_store_cancel);
  */
 int tpm_open(struct inode *inode, struct file *file)
 {
-       int rc = 0, minor = iminor(inode);
+       int minor = iminor(inode);
        struct tpm_chip *chip = NULL, *pos;
 
-       spin_lock(&driver_lock);
-
-       list_for_each_entry(pos, &tpm_chip_list, list) {
+       rcu_read_lock();
+       list_for_each_entry_rcu(pos, &tpm_chip_list, list) {
                if (pos->vendor.miscdev.minor == minor) {
                        chip = pos;
+                       get_device(chip->dev);
                        break;
                }
        }
+       rcu_read_unlock();
 
-       if (chip == NULL) {
-               rc = -ENODEV;
-               goto err_out;
-       }
+       if (!chip)
+               return -ENODEV;
 
        if (test_and_set_bit(0, &chip->is_open)) {
                dev_dbg(chip->dev, "Another process owns this TPM\n");
-               rc = -EBUSY;
-               goto err_out;
+               put_device(chip->dev);
+               return -EBUSY;
        }
 
-       get_device(chip->dev);
-
-       spin_unlock(&driver_lock);
-
        chip->data_buffer = kmalloc(TPM_BUFSIZE * sizeof(u8), GFP_KERNEL);
        if (chip->data_buffer == NULL) {
                clear_bit(0, &chip->is_open);
@@ -999,26 +994,23 @@ int tpm_open(struct inode *inode, struct file *file)
 
        file->private_data = chip;
        return 0;
-
-err_out:
-       spin_unlock(&driver_lock);
-       return rc;
 }
 EXPORT_SYMBOL_GPL(tpm_open);
 
+/*
+ * Called on file close
+ */
 int tpm_release(struct inode *inode, struct file *file)
 {
        struct tpm_chip *chip = file->private_data;
 
        flush_scheduled_work();
-       spin_lock(&driver_lock);
        file->private_data = NULL;
        del_singleshot_timer_sync(&chip->user_read_timer);
        atomic_set(&chip->data_pending, 0);
+       kfree(chip->data_buffer);
        clear_bit(0, &chip->is_open);
        put_device(chip->dev);
-       kfree(chip->data_buffer);
-       spin_unlock(&driver_lock);
        return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_release);
@@ -1092,13 +1084,11 @@ void tpm_remove_hardware(struct device *dev)
        }
 
        spin_lock(&driver_lock);
-
-       list_del(&chip->list);
-
+       list_del_rcu(&chip->list);
        spin_unlock(&driver_lock);
+       synchronize_rcu();
 
        misc_deregister(&chip->vendor.miscdev);
-
        sysfs_remove_group(&dev->kobj, chip->vendor.attr_group);
        tpm_bios_log_teardown(chip->bios_dir);
 
@@ -1146,8 +1136,7 @@ EXPORT_SYMBOL_GPL(tpm_pm_resume);
 /*
  * Once all references to platform device are down to 0,
  * release all allocated structures.
- * In case vendor provided release function,
- * call it too.
+ * In case vendor provided release function, call it too.
  */
 static void tpm_dev_release(struct device *dev)
 {
@@ -1155,7 +1144,6 @@ static void tpm_dev_release(struct device *dev)
 
        if (chip->vendor.release)
                chip->vendor.release(dev);
-
        chip->release(dev);
 
        clear_bit(chip->dev_num, dev_mask);
@@ -1170,8 +1158,8 @@ static void tpm_dev_release(struct device *dev)
  * upon errant exit from this function specific probe function should call
  * pci_disable_device
  */
-struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vendor_specific
-                                      *entry)
+struct tpm_chip *tpm_register_hardware(struct device *dev,
+                                       const struct tpm_vendor_specific *entry)
 {
 #define DEVNAME_SIZE 7
 
@@ -1230,21 +1218,20 @@ struct tpm_chip *tpm_register_hardware(struct device *dev, const struct tpm_vend
                return NULL;
        }
 
-       spin_lock(&driver_lock);
-
-       list_add(&chip->list, &tpm_chip_list);
-
-       spin_unlock(&driver_lock);
-
        if (sysfs_create_group(&dev->kobj, chip->vendor.attr_group)) {
-               list_del(&chip->list);
                misc_deregister(&chip->vendor.miscdev);
                put_device(chip->dev);
+
                return NULL;
        }
 
        chip->bios_dir = tpm_bios_log_setup(devname);
 
+       /* Make chip available */
+       spin_lock(&driver_lock);
+       list_add_rcu(&chip->list, &tpm_chip_list);
+       spin_unlock(&driver_lock);
+
        return chip;
 }
 EXPORT_SYMBOL_GPL(tpm_register_hardware);