Re: [PATCH RESEND 2/3] tpm: replace dynamically allocated bios_dir with a static array

From: Nayna
Date: Mon Oct 10 2016 - 14:53:57 EST




On 10/02/2016 12:55 AM, Jarkko Sakkinen wrote:
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: Jason Gunthorpe <jgunthorpe@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Nayna Jain <nayna@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
drivers/char/tpm/tpm-chip.c | 9 +++---
drivers/char/tpm/tpm.h | 3 +-
drivers/char/tpm/tpm_eventlog.c | 62 +++++++++++++++++++----------------------
drivers/char/tpm/tpm_eventlog.h | 10 +++----
4 files changed, 41 insertions(+), 43 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index e595013..a56b609 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/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)
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 4d183c9..4c118a4 100644
--- a/drivers/char/tpm/tpm.h
+++ b/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;
diff --git a/drivers/char/tpm/tpm_eventlog.c b/drivers/char/tpm/tpm_eventlog.c
index 75e6644..f5e1d06 100644
--- a/drivers/char/tpm/tpm_eventlog.c
+++ b/drivers/char/tpm/tpm_eventlog.c
@@ -368,54 +368,50 @@ static int is_bad(void *p)
return 0;
}

-struct dentry **tpm_bios_log_setup(const char *name)
+int tpm_bios_log_setup(struct tpm_chip *chip)
{
- struct dentry **ret = NULL, *tpm_dir, *bin_file, *ascii_file;
+ const char *name = dev_name(&chip->dev);
+ unsigned int cnt;

- tpm_dir = securityfs_create_dir(name, NULL);
- if (is_bad(tpm_dir))
- goto out;
+ cnt = 0;
+ chip->bios_dir[cnt] =
+ securityfs_create_dir(name, NULL);
+ if (is_bad(chip->bios_dir[cnt]))
+ goto err;
+ cnt++;

- bin_file =
+ chip->bios_dir[cnt] =
securityfs_create_file("binary_bios_measurements",
- S_IRUSR | S_IRGRP, tpm_dir,
+ S_IRUSR | S_IRGRP, chip->bios_dir[0],
(void *)&tpm_binary_b_measurments_seqops,
&tpm_bios_measurements_ops);
- if (is_bad(bin_file))
- goto out_tpm;
+ if (is_bad(chip->bios_dir[cnt]))
+ goto err;
+ cnt++;

- ascii_file =
+ chip->bios_dir[cnt] =
securityfs_create_file("ascii_bios_measurements",
- S_IRUSR | S_IRGRP, tpm_dir,
+ S_IRUSR | S_IRGRP, chip->bios_dir[0],
(void *)&tpm_ascii_b_measurments_seqops,
&tpm_bios_measurements_ops);
- if (is_bad(ascii_file))
- goto out_bin;
+ if (is_bad(chip->bios_dir[cnt]))
+ goto err;
+ cnt++;

- 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;
-
- 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;

The updated patch looks fine.
Just, I am not sure if NULL assignment is needed.

+ 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--) {
+ if (chip->bios_dir[i])

Probably, this check is not required because securityfs_remove() takes care of checking both NULL and err dentry.

Thanks & Regards,
- Nayna

+ securityfs_remove(chip->bios_dir[i]);
+ }
}
diff --git a/drivers/char/tpm/tpm_eventlog.h b/drivers/char/tpm/tpm_eventlog.h
index 8de62b0..fd3357e 100644
--- a/drivers/char/tpm/tpm_eventlog.h
+++ b/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