Re: [PATCH 1/2] sysctl: introduce new proc handler proc_dobool

Thomas Huth
2021-08-18T09:39:02Z

On 03/08/2021 12.59, Thomas Huth wrote:
> From: Jia He <hejianet@gmail.com>
>
> This is to let bool variable could be correctly displayed in
> big/little endian sysctl procfs. sizeof(bool) is arch dependent,
> proc_dobool should work in all arches.
>
> Suggested-by: Pan Xinhui <xinhui@linux.vnet.ibm.com>
> Signed-off-by: Jia He <hejianet@gmail.com>
> [thuth: rebased the patch to the current kernel version]
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> include/linux/sysctl.h | 2 ++
> kernel/sysctl.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 44 insertions(+)
>
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index d99ca99837de..1fa2b69c6fc3 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -48,6 +48,8 @@ typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
> size_t *lenp, loff_t *ppos);
>
> int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
> +int proc_dobool(struct ctl_table *table, int write, void *buffer,
> + size_t *lenp, loff_t *ppos);
> int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
> int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
> int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 272f4a272f8c..25e49b4d8049 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -536,6 +536,21 @@ static void proc_put_char(void **buf, size_t *size, char c)
> }
> }
>
> +static int do_proc_dobool_conv(bool *negp, unsigned long *lvalp,
> + int *valp,
> + int write, void *data)
> +{
> + if (write) {
> + *(bool *)valp = *lvalp;
> + } else {
> + int val = *(bool *)valp;
> +
> + *lvalp = (unsigned long)val;
> + *negp = false;
> + }
> + return 0;
> +}
> +
> static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
> int *valp,
> int write, void *data)
> @@ -798,6 +813,26 @@ static int do_proc_douintvec(struct ctl_table *table, int write,
> buffer, lenp, ppos, conv, data);
> }
>
> +/**
> + * proc_dobool - read/write a bool
> + * @table: the sysctl table
> + * @write: %TRUE if this is a write to the sysctl file
> + * @buffer: the user buffer
> + * @lenp: the size of the user buffer
> + * @ppos: file position
> + *
> + * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
> + * values from/to the user buffer, treated as an ASCII string.
> + *
> + * Returns 0 on success.
> + */
> +int proc_dobool(struct ctl_table *table, int write, void *buffer,
> + size_t *lenp, loff_t *ppos)
> +{
> + return do_proc_dointvec(table, write, buffer, lenp, ppos,
> + do_proc_dobool_conv, NULL);
> +}
> +
> /**
> * proc_dointvec - read a vector of integers
> * @table: the sysctl table
> @@ -1630,6 +1665,12 @@ int proc_dostring(struct ctl_table *table, int write,
> return -ENOSYS;
> }
>
> +int proc_dobool(struct ctl_table *table, int write,
> + void *buffer, size_t *lenp, loff_t *ppos)
> +{
> + return -ENOSYS;
> +}
> +
> int proc_dointvec(struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> @@ -3425,6 +3466,7 @@ int __init sysctl_init(void)
> * No sense putting this after each symbol definition, twice,
> * exception granted :-)
> */
> +EXPORT_SYMBOL(proc_dobool);
> EXPORT_SYMBOL(proc_dointvec);
> EXPORT_SYMBOL(proc_douintvec);
> EXPORT_SYMBOL(proc_dointvec_jiffies);
>

Friendly ping!

Luis, Kees, Iurii, could you please have a look and provide an Ack if this
looks ok to you?

Thanks,
Thomas