tpm: Use container_of to locate the tpm_chip in tpm_open

misc_open sets the file->private_date to the misc_dev when calling
open. We can use container_of to go from the misc_dev back to the
tpm_chip.

Future clean ups will move tpm_open into a new file and this change
means we do not have to export the tpm_chip list.

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Joel Schopp <jschopp@linux.vnet.ibm.com>
Reviewed-by: Peter Huewe <peterhuewe@gmx.de>
Acked-by: Ashley Lai <adlai@linux.vnet.ibm.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

1 files changed, 4 insertions, 17 deletions

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 71eb8c762880..c3ab508222af 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1170,38 +1170,25 @@ EXPORT_SYMBOL_GPL(wait_for_tpm_stat);
  */
 int tpm_open(struct inode *inode, struct file *file)
 {
-        int minor = iminor(inode);
-        struct tpm_chip *chip = NULL, *pos;
-
-        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)
-                return -ENODEV;
+        struct miscdevice *misc = file->private_data;
+        struct tpm_chip *chip = container_of(misc, struct tpm_chip,
+                                             vendor.miscdev);
 
         if (test_and_set_bit(0, &chip->is_open)) {
                 dev_dbg(chip->dev, "Another process owns this TPM\n");
-                put_device(chip->dev);
                 return -EBUSY;
         }
 
         chip->data_buffer = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
         if (chip->data_buffer == NULL) {
                 clear_bit(0, &chip->is_open);
-                put_device(chip->dev);
                 return -ENOMEM;
         }
 
         atomic_set(&chip->data_pending, 0);
 
         file->private_data = chip;
+        get_device(chip->dev);
         return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_open);