linux-kernel - [PATCH] tpm: make all 'class' structures const

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Date:   Tue, 20 Jun 2023 16:46:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Ivan Orlov <ivan.orlov0322@...il.com>,
        Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH] tpm: make all 'class' structures const

From: Ivan Orlov <ivan.orlov0322@...il.com>

Now that the driver core allows for struct class to be in read-only
memory, making all 'class' structures to be declared at build time
placing them into read-only memory, instead of having to be dynamically
allocated at load time.

Cc: Peter Huewe <peterhuewe@....de>
Cc: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: linux-integrity@...r.kernel.org
Suggested-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/char/tpm/tpm-chip.c      | 11 ++++++++---
 drivers/char/tpm/tpm-interface.c | 21 +++++++++------------
 drivers/char/tpm/tpm.h           |  4 ++--
 drivers/char/tpm/tpm2-space.c    |  2 +-
 4 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index cd48033b804a..7c028f0b9d38 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -28,8 +28,13 @@
 DEFINE_IDR(dev_nums_idr);
 static DEFINE_MUTEX(idr_lock);
 
-struct class *tpm_class;
-struct class *tpmrm_class;
+const struct class tpm_class = {
+	.name = "tpm",
+	.shutdown_pre = tpm_class_shutdown,
+};
+const struct class tpmrm_class = {
+	.name = "tmprm",
+};
 dev_t tpm_devt;
 
 static int tpm_request_locality(struct tpm_chip *chip)
@@ -336,7 +341,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
 
 	device_initialize(&chip->dev);
 
-	chip->dev.class = tpm_class;
+	chip->dev.class = &tpm_class;
 	chip->dev.release = tpm_dev_release;
 	chip->dev.parent = pdev;
 	chip->dev.groups = chip->groups;
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 586ca10b0d72..66b16d26eecc 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -476,18 +476,15 @@ static int __init tpm_init(void)
 {
 	int rc;
 
-	tpm_class = class_create("tpm");
-	if (IS_ERR(tpm_class)) {
+	rc = class_register(&tpm_class);
+	if (rc) {
 		pr_err("couldn't create tpm class\n");
-		return PTR_ERR(tpm_class);
+		return rc;
 	}
 
-	tpm_class->shutdown_pre = tpm_class_shutdown;
-
-	tpmrm_class = class_create("tpmrm");
-	if (IS_ERR(tpmrm_class)) {
+	rc = class_register(&tpmrm_class);
+	if (rc) {
 		pr_err("couldn't create tpmrm class\n");
-		rc = PTR_ERR(tpmrm_class);
 		goto out_destroy_tpm_class;
 	}
 
@@ -508,9 +505,9 @@ static int __init tpm_init(void)
 out_unreg_chrdev:
 	unregister_chrdev_region(tpm_devt, 2 * TPM_NUM_DEVICES);
 out_destroy_tpmrm_class:
-	class_destroy(tpmrm_class);
+	class_unregister(&tpmrm_class);
 out_destroy_tpm_class:
-	class_destroy(tpm_class);
+	class_unregister(&tpm_class);
 
 	return rc;
 }
@@ -518,8 +515,8 @@ static int __init tpm_init(void)
 static void __exit tpm_exit(void)
 {
 	idr_destroy(&dev_nums_idr);
-	class_destroy(tpm_class);
-	class_destroy(tpmrm_class);
+	class_unregister(&tpm_class);
+	class_unregister(&tpmrm_class);
 	unregister_chrdev_region(tpm_devt, 2*TPM_NUM_DEVICES);
 	tpm_dev_common_exit();
 }
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 460bb85dd142..61445f1dc46d 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -230,8 +230,8 @@ enum tpm2_pt_props {
  * compiler warnings about stack frame size. */
 #define TPM_MAX_RNG_DATA	128
 
-extern struct class *tpm_class;
-extern struct class *tpmrm_class;
+extern const struct class tpm_class;
+extern const struct class tpmrm_class;
 extern dev_t tpm_devt;
 extern const struct file_operations tpm_fops;
 extern const struct file_operations tpmrm_fops;
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index ffb35f0154c1..363afdd4d1d3 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -606,7 +606,7 @@ int tpm_devs_add(struct tpm_chip *chip)
 
 	device_initialize(&chip->devs);
 	chip->devs.parent = chip->dev.parent;
-	chip->devs.class = tpmrm_class;
+	chip->devs.class = &tpmrm_class;
 
 	/*
 	 * Get extra reference on main device to hold on behalf of devs.
-- 
2.41.0