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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 /kernel
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 'kernel')
-rw-r--r--kernel/sys.c2
-rw-r--r--kernel/utsname_sysctl.c23
2 files changed, 25 insertions, 0 deletions
diff --git a/kernel/sys.c b/kernel/sys.c
index 58459509b14c..d06c091e0345 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1286,6 +1286,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
memset(u->nodename + len, 0, sizeof(u->nodename) - len);
errno = 0;
}
+ uts_proc_notify(UTS_PROC_HOSTNAME);
up_write(&uts_sem);
return errno;
}
@@ -1336,6 +1337,7 @@ SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
memset(u->domainname + len, 0, sizeof(u->domainname) - len);
errno = 0;
}
+ uts_proc_notify(UTS_PROC_DOMAINNAME);
up_write(&uts_sem);
return errno;
}
diff --git a/kernel/utsname_sysctl.c b/kernel/utsname_sysctl.c
index a2cd77e70d4d..3b0d48ebf81d 100644
--- a/kernel/utsname_sysctl.c
+++ b/kernel/utsname_sysctl.c
@@ -13,6 +13,7 @@
#include <linux/uts.h>
#include <linux/utsname.h>
#include <linux/sysctl.h>
+#include <linux/wait.h>
static void *get_uts(ctl_table *table, int write)
{
@@ -51,12 +52,19 @@ static int proc_do_uts_string(ctl_table *table, int write,
uts_table.data = get_uts(table, write);
r = proc_dostring(&uts_table,write,buffer,lenp, ppos);
put_uts(table, write, uts_table.data);
+
+ if (write)
+ proc_sys_poll_notify(table->poll);
+
return r;
}
#else
#define proc_do_uts_string NULL
#endif
+static DEFINE_CTL_TABLE_POLL(hostname_poll);
+static DEFINE_CTL_TABLE_POLL(domainname_poll);
+
static struct ctl_table uts_kern_table[] = {
{
.procname = "ostype",
@@ -85,6 +93,7 @@ static struct ctl_table uts_kern_table[] = {
.maxlen = sizeof(init_uts_ns.name.nodename),
.mode = 0644,
.proc_handler = proc_do_uts_string,
+ .poll = &hostname_poll,
},
{
.procname = "domainname",
@@ -92,6 +101,7 @@ static struct ctl_table uts_kern_table[] = {
.maxlen = sizeof(init_uts_ns.name.domainname),
.mode = 0644,
.proc_handler = proc_do_uts_string,
+ .poll = &domainname_poll,
},
{}
};
@@ -105,6 +115,19 @@ static struct ctl_table uts_root_table[] = {
{}
};
+#ifdef CONFIG_PROC_SYSCTL
+/*
+ * Notify userspace about a change in a certain entry of uts_kern_table,
+ * identified by the parameter proc.
+ */
+void uts_proc_notify(enum uts_proc proc)
+{
+ struct ctl_table *table = &uts_kern_table[proc];
+
+ proc_sys_poll_notify(table->poll);
+}
+#endif
+
static int __init utsname_sysctl_init(void)
{
register_sysctl_table(uts_root_table);