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sysctl: introduce new proc handler proc_dobool

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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>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Jia He 2021-08-03 12:59:36 +02:00 committed by Chuck Lever
parent 5c11720767
commit a2071573d6
2 changed files with 44 additions and 0 deletions
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2
include/linux/sysctl.h
View file

@ -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 *);

42
kernel/sysctl.c
View file

@ -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);