tpm: Replace device number bitmap with IDR

commit 15516788e581eb32ec1c50e5f00aba3faf95d817 upstream.

Replace the device number bitmap with IDR. Extend the number of devices we
can create to 64k.
Since an IDR allows us to associate a pointer with an ID, we use this now
to rewrite tpm_chip_find_get() to simply look up the chip pointer by the
given device ID.

Protect the IDR calls with a mutex.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: stefanberger

drivers/char/tpm/tpm-chip.c

@@ -29,9 +29,8 @@
 #include "tpm.h"
 #include "tpm_eventlog.h"
 
-static DECLARE_BITMAP(dev_mask, TPM_NUM_DEVICES);
-static LIST_HEAD(tpm_chip_list);
-static DEFINE_SPINLOCK(driver_lock);
+DEFINE_IDR(dev_nums_idr);
+static DEFINE_MUTEX(idr_lock);
 
 struct class *tpm_class;
 dev_t tpm_devt;
@@ -92,20 +91,30 @@ EXPORT_SYMBOL_GPL(tpm_put_ops);
   */
 struct tpm_chip *tpm_chip_find_get(int chip_num)
 {
-	struct tpm_chip *pos, *chip = NULL;
+	struct tpm_chip *chip, *res = NULL;
+	int chip_prev;
+
+	mutex_lock(&idr_lock);
+
+	if (chip_num == TPM_ANY_NUM) {
+		chip_num = 0;
+		do {
+			chip_prev = chip_num;
+			chip = idr_get_next(&dev_nums_idr, &chip_num);
+			if (chip && !tpm_try_get_ops(chip)) {
+				res = chip;
+				break;
+			}
+		} while (chip_prev != chip_num);
+	} else {
+		chip = idr_find_slowpath(&dev_nums_idr, chip_num);
+		if (chip && !tpm_try_get_ops(chip))
+			res = chip;
+	}
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(pos, &tpm_chip_list, list) {
-		if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num)
-			continue;
+	mutex_unlock(&idr_lock);
 
-		/* rcu prevents chip from being free'd */
-		if (!tpm_try_get_ops(pos))
-			chip = pos;
-		break;
-	}
-	rcu_read_unlock();
-	return chip;
+	return res;
 }
 
 /**
@@ -118,9 +127,10 @@ static void tpm_dev_release(struct device *dev)
 {
 	struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
 
-	spin_lock(&driver_lock);
-	clear_bit(chip->dev_num, dev_mask);
-	spin_unlock(&driver_lock);
+	mutex_lock(&idr_lock);
+	idr_remove(&dev_nums_idr, chip->dev_num);
+	mutex_unlock(&idr_lock);
+
 	kfree(chip);
 }
 
@@ -173,28 +183,26 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev,
 				 const struct tpm_class_ops *ops)
 {
 	struct tpm_chip *chip;
+	int rc;
 
 	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
 	if (chip == NULL)
 		return ERR_PTR(-ENOMEM);
 
 	mutex_init(&chip->tpm_mutex);
 	init_rwsem(&chip->ops_sem);
-	INIT_LIST_HEAD(&chip->list);
 
 	chip->ops = ops;
 
-	spin_lock(&driver_lock);
-	chip->dev_num = find_first_zero_bit(dev_mask, TPM_NUM_DEVICES);
-	spin_unlock(&driver_lock);
-
-	if (chip->dev_num >= TPM_NUM_DEVICES) {
+	mutex_lock(&idr_lock);
+	rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
+	mutex_unlock(&idr_lock);
+	if (rc < 0) {
 		dev_err(dev, "No available tpm device numbers\n");
 		kfree(chip);
-		return ERR_PTR(-ENOMEM);
+		return ERR_PTR(rc);
 	}
-
-	set_bit(chip->dev_num, dev_mask);
+	chip->dev_num = rc;
 
 	scnprintf(chip->devname, sizeof(chip->devname), "tpm%d", chip->dev_num);
 
@@ -252,19 +260,28 @@ static int tpm_add_char_device(struct tpm_chip *chip)
 		return rc;
 	}
 
+	/* Make the chip available. */
+	mutex_lock(&idr_lock);
+	idr_replace(&dev_nums_idr, chip, chip->dev_num);
+	mutex_unlock(&idr_lock);
+
 	return rc;
 }
 
 static void tpm_del_char_device(struct tpm_chip *chip)
 {
 	cdev_del(&chip->cdev);
+	device_del(&chip->dev);
+
+	/* Make the chip unavailable. */
+	mutex_lock(&idr_lock);
+	idr_replace(&dev_nums_idr, NULL, chip->dev_num);
+	mutex_unlock(&idr_lock);
 
 	/* Make the driver uncallable. */
 	down_write(&chip->ops_sem);
 	chip->ops = NULL;
 	up_write(&chip->ops_sem);
-
-	device_del(&chip->dev);
 }
 
 static int tpm1_chip_register(struct tpm_chip *chip)
@@ -319,11 +336,6 @@ int tpm_chip_register(struct tpm_chip *chip)
 	if (rc)
 		goto out_err;
 
-	/* Make the chip available. */
-	spin_lock(&driver_lock);
-	list_add_tail_rcu(&chip->list, &tpm_chip_list);
-	spin_unlock(&driver_lock);
-
 	chip->flags |= TPM_CHIP_FLAG_REGISTERED;
 
 	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
@@ -360,11 +372,6 @@ void tpm_chip_unregister(struct tpm_chip *chip)
 	if (!(chip->flags & TPM_CHIP_FLAG_REGISTERED))
 		return;
 
-	spin_lock(&driver_lock);
-	list_del_rcu(&chip->list);
-	spin_unlock(&driver_lock);
-	synchronize_rcu();
-
 	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
 		sysfs_remove_link(&chip->dev.parent->kobj, "ppi");
 

drivers/char/tpm/tpm-interface.c

@@ -1127,6 +1127,7 @@ static int __init tpm_init(void)
 
 static void __exit tpm_exit(void)
 {
+	idr_destroy(&dev_nums_idr);
 	class_destroy(tpm_class);
 	unregister_chrdev_region(tpm_devt, TPM_NUM_DEVICES);
 }

drivers/char/tpm/tpm.h

@@ -34,7 +34,7 @@
 enum tpm_const {
 	TPM_MINOR = 224,	/* officially assigned */
 	TPM_BUFSIZE = 4096,
-	TPM_NUM_DEVICES = 256,
+	TPM_NUM_DEVICES = 65536,
 	TPM_RETRY = 50,		/* 5 seconds */
 };
 
@@ -200,8 +200,6 @@ struct tpm_chip {
 	acpi_handle acpi_dev_handle;
 	char ppi_version[TPM_PPI_VERSION_LEN + 1];
 #endif /* CONFIG_ACPI */
-
-	struct list_head list;
 };
 
 #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
@@ -497,6 +495,7 @@ static inline void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
 extern struct class *tpm_class;
 extern dev_t tpm_devt;
 extern const struct file_operations tpm_fops;
+extern struct idr dev_nums_idr;
 
 enum tpm_transmit_flags {
 	TPM_TRANSMIT_UNLOCKED	= BIT(0),