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linux-next/fs/nfs/callback.c
Rafael J. Wysocki 8314418629 Freezer: make kernel threads nonfreezable by default
Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:02 -07:00

217 lines
5.0 KiB
C

/*
* linux/fs/nfs/callback.c
*
* Copyright (C) 2004 Trond Myklebust
*
* NFSv4 callback handling
*/
#include <linux/completion.h>
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/nfs_fs.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <net/inet_sock.h>
#include "nfs4_fs.h"
#include "callback.h"
#include "internal.h"
#define NFSDBG_FACILITY NFSDBG_CALLBACK
struct nfs_callback_data {
unsigned int users;
struct svc_serv *serv;
pid_t pid;
struct completion started;
struct completion stopped;
};
static struct nfs_callback_data nfs_callback_info;
static DEFINE_MUTEX(nfs_callback_mutex);
static struct svc_program nfs4_callback_program;
unsigned int nfs_callback_set_tcpport;
unsigned short nfs_callback_tcpport;
static const int nfs_set_port_min = 0;
static const int nfs_set_port_max = 65535;
static int param_set_port(const char *val, struct kernel_param *kp)
{
char *endp;
int num = simple_strtol(val, &endp, 0);
if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
return -EINVAL;
*((int *)kp->arg) = num;
return 0;
}
module_param_call(callback_tcpport, param_set_port, param_get_int,
&nfs_callback_set_tcpport, 0644);
/*
* This is the callback kernel thread.
*/
static void nfs_callback_svc(struct svc_rqst *rqstp)
{
int err;
__module_get(THIS_MODULE);
lock_kernel();
nfs_callback_info.pid = current->pid;
daemonize("nfsv4-svc");
/* Process request with signals blocked, but allow SIGKILL. */
allow_signal(SIGKILL);
set_freezable();
complete(&nfs_callback_info.started);
for(;;) {
char buf[RPC_MAX_ADDRBUFLEN];
if (signalled()) {
if (nfs_callback_info.users == 0)
break;
flush_signals(current);
}
/*
* Listen for a request on the socket
*/
err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
if (err == -EAGAIN || err == -EINTR)
continue;
if (err < 0) {
printk(KERN_WARNING
"%s: terminating on error %d\n",
__FUNCTION__, -err);
break;
}
dprintk("%s: request from %s\n", __FUNCTION__,
svc_print_addr(rqstp, buf, sizeof(buf)));
svc_process(rqstp);
}
svc_exit_thread(rqstp);
nfs_callback_info.pid = 0;
complete(&nfs_callback_info.stopped);
unlock_kernel();
module_put_and_exit(0);
}
/*
* Bring up the server process if it is not already up.
*/
int nfs_callback_up(void)
{
struct svc_serv *serv;
int ret = 0;
lock_kernel();
mutex_lock(&nfs_callback_mutex);
if (nfs_callback_info.users++ || nfs_callback_info.pid != 0)
goto out;
init_completion(&nfs_callback_info.started);
init_completion(&nfs_callback_info.stopped);
serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
ret = -ENOMEM;
if (!serv)
goto out_err;
ret = svc_makesock(serv, IPPROTO_TCP, nfs_callback_set_tcpport,
SVC_SOCK_ANONYMOUS);
if (ret <= 0)
goto out_destroy;
nfs_callback_tcpport = ret;
dprintk("Callback port = 0x%x\n", nfs_callback_tcpport);
ret = svc_create_thread(nfs_callback_svc, serv);
if (ret < 0)
goto out_destroy;
nfs_callback_info.serv = serv;
wait_for_completion(&nfs_callback_info.started);
out:
mutex_unlock(&nfs_callback_mutex);
unlock_kernel();
return ret;
out_destroy:
dprintk("Couldn't create callback socket or server thread; err = %d\n",
ret);
svc_destroy(serv);
out_err:
nfs_callback_info.users--;
goto out;
}
/*
* Kill the server process if it is not already up.
*/
void nfs_callback_down(void)
{
lock_kernel();
mutex_lock(&nfs_callback_mutex);
nfs_callback_info.users--;
do {
if (nfs_callback_info.users != 0 || nfs_callback_info.pid == 0)
break;
if (kill_proc(nfs_callback_info.pid, SIGKILL, 1) < 0)
break;
} while (wait_for_completion_timeout(&nfs_callback_info.stopped, 5*HZ) == 0);
mutex_unlock(&nfs_callback_mutex);
unlock_kernel();
}
static int nfs_callback_authenticate(struct svc_rqst *rqstp)
{
struct sockaddr_in *addr = svc_addr_in(rqstp);
struct nfs_client *clp;
char buf[RPC_MAX_ADDRBUFLEN];
/* Don't talk to strangers */
clp = nfs_find_client(addr, 4);
if (clp == NULL)
return SVC_DROP;
dprintk("%s: %s NFSv4 callback!\n", __FUNCTION__,
svc_print_addr(rqstp, buf, sizeof(buf)));
nfs_put_client(clp);
switch (rqstp->rq_authop->flavour) {
case RPC_AUTH_NULL:
if (rqstp->rq_proc != CB_NULL)
return SVC_DENIED;
break;
case RPC_AUTH_UNIX:
break;
case RPC_AUTH_GSS:
/* FIXME: RPCSEC_GSS handling? */
default:
return SVC_DENIED;
}
return SVC_OK;
}
/*
* Define NFS4 callback program
*/
static struct svc_version *nfs4_callback_version[] = {
[1] = &nfs4_callback_version1,
};
static struct svc_stat nfs4_callback_stats;
static struct svc_program nfs4_callback_program = {
.pg_prog = NFS4_CALLBACK, /* RPC service number */
.pg_nvers = ARRAY_SIZE(nfs4_callback_version), /* Number of entries */
.pg_vers = nfs4_callback_version, /* version table */
.pg_name = "NFSv4 callback", /* service name */
.pg_class = "nfs", /* authentication class */
.pg_stats = &nfs4_callback_stats,
.pg_authenticate = nfs_callback_authenticate,
};