sysctl: introduce new proc handler proc_dobool

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>

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index d99ca99..1fa2b69 100644 (file)
--- 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 272f4a2..25e49b4 100644 (file)
--- 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);