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

[Nayna <nayna@linux.vnet.ibm.com>]

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@obsidianresearch.com>
> Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>   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
>