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authorLucas De Marchi <lucas.demarchi@profusion.mobi>2011-11-02 13:39:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-11-02 16:07:02 -0700
commitf1ecf06854a66ee663f4d4cf029c78cd62a15e04 (patch)
treecbe863057fa14b9390746db6d2b1812a2f874b48 /include/linux
parent088024b1deee206cd37eff980138e918837aabdb (diff)
sysctl: add support for poll()
Adding support for poll() in sysctl fs allows userspace to receive notifications of changes in sysctl entries. This adds a infrastructure to allow files in sysctl fs to be pollable and implements it for hostname and domainname. [akpm@linux-foundation.org: s/declare/define/ for definitions] Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Greg KH <gregkh@suse.de> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/sysctl.h22
-rw-r--r--include/linux/utsname.h16
2 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 9a1ec10fd504..703cfa33a3ca 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -931,6 +931,7 @@ enum
#ifdef __KERNEL__
#include <linux/list.h>
#include <linux/rcupdate.h>
+#include <linux/wait.h>
/* For the /proc/sys support */
struct ctl_table;
@@ -1011,6 +1012,26 @@ extern int proc_do_large_bitmap(struct ctl_table *, int,
* cover common cases.
*/
+/* Support for userspace poll() to watch for changes */
+struct ctl_table_poll {
+ atomic_t event;
+ wait_queue_head_t wait;
+};
+
+static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
+{
+ return (void *)(unsigned long)atomic_read(&poll->event);
+}
+
+void proc_sys_poll_notify(struct ctl_table_poll *poll);
+
+#define __CTL_TABLE_POLL_INITIALIZER(name) { \
+ .event = ATOMIC_INIT(0), \
+ .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
+
+#define DEFINE_CTL_TABLE_POLL(name) \
+ struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
+
/* A sysctl table is an array of struct ctl_table: */
struct ctl_table
{
@@ -1021,6 +1042,7 @@ struct ctl_table
struct ctl_table *child;
struct ctl_table *parent; /* Automatically set */
proc_handler *proc_handler; /* Callback for text formatting */
+ struct ctl_table_poll *poll;
void *extra1;
void *extra2;
};
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 4e5b0213fdc1..c714ed75eae2 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -37,6 +37,14 @@ struct new_utsname {
#include <linux/nsproxy.h>
#include <linux/err.h>
+enum uts_proc {
+ UTS_PROC_OSTYPE,
+ UTS_PROC_OSRELEASE,
+ UTS_PROC_VERSION,
+ UTS_PROC_HOSTNAME,
+ UTS_PROC_DOMAINNAME,
+};
+
struct user_namespace;
extern struct user_namespace init_user_ns;
@@ -80,6 +88,14 @@ static inline struct uts_namespace *copy_utsname(unsigned long flags,
}
#endif
+#ifdef CONFIG_PROC_SYSCTL
+extern void uts_proc_notify(enum uts_proc proc);
+#else
+static inline void uts_proc_notify(enum uts_proc proc)
+{
+}
+#endif
+
static inline struct new_utsname *utsname(void)
{
return &current->nsproxy->uts_ns->name;