Re: [PATCH] sysctl: Use replace **void with **char in proc_put_*

[Joel Granados]

On Wed, Sep 16, 2026 at 01:44:28PM +0200, Joel Granados wrote:
> Replace **void argument with **char in the proc_put_* functions. These
> are leftovers from before commit 32927393dc1c ("sysctl: pass kernel
> pointers to ->proc_handler") where a cast to char __user** from void
> _user** was needed before the put_user call.
> 
> Suggested-by: Bradley Morgan <include@xxxxxxxxx>
> Signed-off-by: Joel Granados <joel.granados@xxxxxxxxxx>
> ---
>  kernel/sysctl.c | 34 +++++++++++++++-------------------
>  1 file changed, 15 insertions(+), 19 deletions(-)
> 
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 25577ffc2801267cc69df60a1064ada9efd4b97d..1fefe18bf84e790433a1abf71a4b158f3c1f729f 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -332,7 +332,7 @@ static int proc_get_long(char **buf, size_t *size,
>   * In case of success @buf and @size are updated with the amount of bytes
>   * written.
>   */
> -static void proc_put_long(void **buf, size_t *size, unsigned long val, bool neg)
> +static void proc_put_long(char **buf, size_t *size, unsigned long val, bool neg)
>  {
>  	int len;
>  	char tmp[TMPBUFLEN], *p = tmp;
> @@ -347,15 +347,12 @@ static void proc_put_long(void **buf, size_t *size, unsigned long val, bool neg)
>  }
>  #undef TMPBUFLEN
>  
> -static void proc_put_char(void **buf, size_t *size, char c)
> +static void proc_put_char(char **buf, size_t *size, char c)
>  {
>  	if (*size) {
> -		char **buffer = (char **)buf;
> -		**buffer = c;
> -
> +		**buf = c;
>  		(*size)--;
> -		(*buffer)++;
> -		*buf = *buffer;
> +		(*buf)++;
>  	}
>  }
>  
> @@ -680,12 +677,12 @@ static int apply_conv_on_vec(const union proc_vec_conv conv,
>  			     const struct ctl_table *table,
>  			     const enum proc_vec_type data_type,
>  			     const size_t data_size, const int conv_dir,
> -			     const size_t buf_nbyte, void *buf,
> +			     const size_t buf_nbyte, char *buf,
>  			     size_t *buf_left_final)
>  {
>  	int vec_left, err = 0;
>  	size_t buf_left, nr_conv = 0;
> -	char *data, *data_stage = NULL, *p;
> +	char *data, *data_stage = NULL;
>  	bool is_unsigned = data_type == PROC_VEC_UINT || data_type == PROC_VEC_ULONG;
>  
>  	buf_left = buf_nbyte;
> @@ -694,7 +691,6 @@ static int apply_conv_on_vec(const union proc_vec_conv conv,
>  	if (SYSCTL_USER_TO_KERN(conv_dir)) {
>  		if (buf_left > PAGE_SIZE - 1)
>  			buf_left = PAGE_SIZE - 1;
> -		p = buf;
>  
>  		if (table->maxlen > data_size) {
>  			data_stage = kmemdup(table->data, table->maxlen, GFP_KERNEL);
> @@ -712,11 +708,11 @@ static int apply_conv_on_vec(const union proc_vec_conv conv,
>  		bool neg = false;
>  
>  		if (SYSCTL_USER_TO_KERN(conv_dir)) {
> -			proc_skip_spaces(&p, &buf_left);
> +			proc_skip_spaces(&buf, &buf_left);
>  
>  			if (!buf_left)
>  				break;
> -			err = proc_get_long(&p, &buf_left, &lval, &neg,
> +			err = proc_get_long(&buf, &buf_left, &lval, &neg,
>  					    proc_wspace_sep,
>  					    sizeof(proc_wspace_sep), NULL);
>  			if (!err && neg && is_unsigned)
> @@ -740,7 +736,7 @@ static int apply_conv_on_vec(const union proc_vec_conv conv,
>  
>  	if (SYSCTL_USER_TO_KERN(conv_dir)) {
>  		if (!err && buf_left)
> -			proc_skip_spaces(&p, &buf_left);
> +			proc_skip_spaces(&buf, &buf_left);
>  		if (!nr_conv) {
>  			err = err ? : -EINVAL;
>  			goto out;
> @@ -1221,6 +1217,7 @@ int proc_do_large_bitmap(const struct ctl_table *table, int dir,
>  	unsigned long *bitmap = *(unsigned long **) table->data;
>  	unsigned long *tmp_bitmap = NULL;
>  	char tr_a[] = { '-', ',', '\n' }, tr_b[] = { ',', '\n', 0 }, c = 0;
> +	char *p = buffer;
>  
>  	if (!bitmap || !bitmap_len || !left || (*ppos && SYSCTL_KERN_TO_USER(dir))) {
>  		*lenp = 0;
> @@ -1228,7 +1225,6 @@ int proc_do_large_bitmap(const struct ctl_table *table, int dir,
>  	}
>  
>  	if (SYSCTL_USER_TO_KERN(dir)) {
> -		char *p = buffer;
>  		size_t skipped = 0;
>  
>  		if (left > PAGE_SIZE - 1) {
> @@ -1315,16 +1311,16 @@ int proc_do_large_bitmap(const struct ctl_table *table, int dir,
>  						   bit_a + 1) - 1;
>  
>  			if (!first)
> -				proc_put_char(&buffer, &left, ',');
> -			proc_put_long(&buffer, &left, bit_a, false);
> +				proc_put_char(&p, &left, ',');
> +			proc_put_long(&p, &left, bit_a, false);
>  			if (bit_a != bit_b) {
> -				proc_put_char(&buffer, &left, '-');
> -				proc_put_long(&buffer, &left, bit_b, false);
> +				proc_put_char(&p, &left, '-');
> +				proc_put_long(&p, &left, bit_b, false);
>  			}
>  
>  			first = 0; bit_b++;
>  		}
> -		proc_put_char(&buffer, &left, '\n');
> +		proc_put_char(&p, &left, '\n');
>  	}
>  
>  	if (!err) {
> 
> ---
> base-commit: 99156fbf3562bed74aa57d93b0b3eeec7c7f1ca6
Forgot to mention that this sits on top of the partial_ctlvec changes
which are included in next-20260915.

> change-id: 20260916-lklm-sysctl-void-vs-char-40a0aab31c3e
> 
> Best regards,
> -- 
> Joel Granados <joel.granados@xxxxxxxxxx>
> 
>

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