tpm: replace dynamically allocated bios_dir with a static array

This commit is based on a commit by Nayna Jain. Replaced dynamically
allocated bios_dir with a static array as the size is always constant.
Suggested-by: NJason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: NJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

drivers/char/tpm/tpm-chip.c

@@ -278,14 +278,16 @@ static void tpm_del_char_device(struct tpm_chip *chip)
 
 static int tpm1_chip_register(struct tpm_chip *chip)
 {
+	int rc;
+
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		return 0;
 
 	tpm_sysfs_add_device(chip);
 
-	chip->bios_dir = tpm_bios_log_setup(dev_name(&chip->dev));
+	rc = tpm_bios_log_setup(chip);
 
-	return 0;
+	return rc;
 }
 
 static void tpm1_chip_unregister(struct tpm_chip *chip)
@@ -293,8 +295,7 @@ static void tpm1_chip_unregister(struct tpm_chip *chip)
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		return;
 
-	if (chip->bios_dir)
-		tpm_bios_log_teardown(chip->bios_dir);
+	tpm_bios_log_teardown(chip);
 }
 
 static void tpm_del_legacy_sysfs(struct tpm_chip *chip)

drivers/char/tpm/tpm.h

@@ -40,6 +40,7 @@ enum tpm_const {
 	TPM_BUFSIZE = 4096,
 	TPM_NUM_DEVICES = 65536,
 	TPM_RETRY = 50,		/* 5 seconds */
+	TPM_NUM_EVENT_LOG_FILES = 3,
 };
 
 enum tpm_timeout {
@@ -171,7 +172,7 @@ struct tpm_chip {
 	unsigned long duration[3]; /* jiffies */
 	bool duration_adjusted;
 
-	struct dentry **bios_dir;
+	struct dentry *bios_dir[TPM_NUM_EVENT_LOG_FILES];
 
 	const struct attribute_group *groups[3];
 	unsigned int groups_cnt;

drivers/char/tpm/tpm_eventlog.c

@@ -359,63 +359,50 @@ static const struct file_operations tpm_bios_measurements_ops = {
 	.release = tpm_bios_measurements_release,
 };
 
-static int is_bad(void *p)
+int tpm_bios_log_setup(struct tpm_chip *chip)
 {
-	if (!p)
-		return 1;
-	if (IS_ERR(p) && (PTR_ERR(p) != -ENODEV))
-		return 1;
-	return 0;
-}
-
-struct dentry **tpm_bios_log_setup(const char *name)
-{
-	struct dentry **ret = NULL, *tpm_dir, *bin_file, *ascii_file;
-
-	tpm_dir = securityfs_create_dir(name, NULL);
-	if (is_bad(tpm_dir))
-		goto out;
-
-	bin_file =
+	const char *name = dev_name(&chip->dev);
+	unsigned int cnt;
+
+	cnt = 0;
+	chip->bios_dir[cnt] = securityfs_create_dir(name, NULL);
+	/* NOTE: securityfs_create_dir can return ENODEV if securityfs is
+	 * compiled out. The caller should ignore the ENODEV return code.
+	 */
+	if (IS_ERR(chip->bios_dir[cnt]))
+		goto err;
+	cnt++;
+
+	chip->bios_dir[cnt] =
 	    securityfs_create_file("binary_bios_measurements",
-				   0440, tpm_dir,
+				   0440, chip->bios_dir[0],
 				   (void *)&tpm_binary_b_measurements_seqops,
 				   &tpm_bios_measurements_ops);
-	if (is_bad(bin_file))
-		goto out_tpm;
+	if (IS_ERR(chip->bios_dir[cnt]))
+		goto err;
+	cnt++;
 
-	ascii_file =
+	chip->bios_dir[cnt] =
 	    securityfs_create_file("ascii_bios_measurements",
-				   0440, tpm_dir,
+				   0440, chip->bios_dir[0],
 				   (void *)&tpm_ascii_b_measurements_seqops,
 				   &tpm_bios_measurements_ops);
-	if (is_bad(ascii_file))
-		goto out_bin;
-
-	ret = kmalloc(3 * sizeof(struct dentry *), GFP_KERNEL);
-	if (!ret)
-		goto out_ascii;
-
-	ret[0] = ascii_file;
-	ret[1] = bin_file;
-	ret[2] = tpm_dir;
+	if (IS_ERR(chip->bios_dir[cnt]))
+		goto err;
+	cnt++;
 
-	return ret;
+	return 0;
 
-out_ascii:
-	securityfs_remove(ascii_file);
-out_bin:
-	securityfs_remove(bin_file);
-out_tpm:
-	securityfs_remove(tpm_dir);
-out:
-	return NULL;
+err:
+	chip->bios_dir[cnt] = NULL;
+	tpm_bios_log_teardown(chip);
+	return -EIO;
 }
 
-void tpm_bios_log_teardown(struct dentry **lst)
+void tpm_bios_log_teardown(struct tpm_chip *chip)
 {
 	int i;
 
-	for (i = 0; i < 3; i++)
-		securityfs_remove(lst[i]);
+	for (i = (TPM_NUM_EVENT_LOG_FILES - 1); i >= 0; i--)
+		securityfs_remove(chip->bios_dir[i]);
 }

drivers/char/tpm/tpm_eventlog.h

@@ -77,14 +77,14 @@ int read_log(struct tpm_bios_log *log);
 
 #if defined(CONFIG_TCG_IBMVTPM) || defined(CONFIG_TCG_IBMVTPM_MODULE) || \
 	defined(CONFIG_ACPI)
-extern struct dentry **tpm_bios_log_setup(const char *);
-extern void tpm_bios_log_teardown(struct dentry **);
+extern int tpm_bios_log_setup(struct tpm_chip *chip);
+extern void tpm_bios_log_teardown(struct tpm_chip *chip);
 #else
-static inline struct dentry **tpm_bios_log_setup(const char *name)
+static inline int tpm_bios_log_setup(struct tpm_chip *chip)
 {
-	return NULL;
+	return 0;
 }
-static inline void tpm_bios_log_teardown(struct dentry **dir)
+static inline void tpm_bios_log_teardown(struct tpm_chip *chip)
 {
 }
 #endif