From f1ecf06854a66ee663f4d4cf029c78cd62a15e04 Mon Sep 17 00:00:00 2001 From: Lucas De Marchi Date: Wed, 2 Nov 2011 13:39:22 -0700 Subject: 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 Cc: Greg KH Cc: Kay Sievers Cc: Al Viro Cc: "Eric W. Biederman" Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sys.c | 2 ++ kernel/utsname_sysctl.c | 23 +++++++++++++++++++++++ 2 files changed, 25 insertions(+) (limited to 'kernel') 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 #include #include +#include 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); -- cgit v1.2.3