tpm: Replace device number bitmap with IDR

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>

3 files changed, 48 insertions, 42 deletions

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 588037733107..f62c8518cd68 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/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;
@@ -88,20 +87,30 @@ 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;
 }
 
 /**
@@ -114,9 +123,10 @@ 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);
 }
 
@@ -142,21 +152,18 @@ struct tpm_chip *tpm_chip_alloc(struct device *dev,
 
         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;
 
         device_initialize(&chip->dev);
 
@@ -242,19 +249,28 @@ 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)
@@ -309,11 +325,6 @@ 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)) {
@@ -350,11 +361,6 @@ 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");
 
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 5caf15421ef7..5397b64b6c96 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1139,6 +1139,7 @@ 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);
 }
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 5fcf7885a4b9..928b47f58771 100644
--- a/drivers/char/tpm/tpm.h
+++ b/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 */
 };
 
@@ -195,8 +195,6 @@ 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)
@@ -492,6 +490,7 @@ 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;
 
 ssize_t tpm_getcap(struct device *, __be32, cap_t *, const char *);
 ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,