Freezer: make kernel threads nonfreezable by default

[linux-2.6/kmemtrace.git] / fs / lockd / svc.c

/*
 * linux/fs/lockd/svc.c
 *
 * This is the central lockd service.
 *
 * FIXME: Separate the lockd NFS server functionality from the lockd NFS
 *        client functionality. Oh why didn't Sun create two separate
 *        services in the first place?
 *
 * Authors:     Olaf Kirch (okir@monad.swb.de)
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/moduleparam.h>

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/uio.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/mutex.h>
#include <linux/freezer.h>

#include <linux/sunrpc/types.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcsock.h>
#include <net/ip.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/sm_inter.h>
#include <linux/nfs.h>

#define NLMDBG_FACILITY         NLMDBG_SVC
#define LOCKD_BUFSIZE           (1024 + NLMSVC_XDRSIZE)
#define ALLOWED_SIGS            (sigmask(SIGKILL))

static struct svc_program       nlmsvc_program;

struct nlmsvc_binding *         nlmsvc_ops;
EXPORT_SYMBOL(nlmsvc_ops);

static DEFINE_MUTEX(nlmsvc_mutex);
static unsigned int             nlmsvc_users;
static pid_t                    nlmsvc_pid;
static struct svc_serv          *nlmsvc_serv;
int                             nlmsvc_grace_period;
unsigned long                   nlmsvc_timeout;

static DECLARE_COMPLETION(lockd_start_done);
static DECLARE_WAIT_QUEUE_HEAD(lockd_exit);

/*
 * These can be set at insmod time (useful for NFS as root filesystem),
 * and also changed through the sysctl interface.  -- Jamie Lokier, Aug 2003
 */
static unsigned long            nlm_grace_period;
static unsigned long            nlm_timeout = LOCKD_DFLT_TIMEO;
static int                      nlm_udpport, nlm_tcpport;
int                             nsm_use_hostnames = 0;

/*
 * Constants needed for the sysctl interface.
 */
static const unsigned long      nlm_grace_period_min = 0;
static const unsigned long      nlm_grace_period_max = 240;
static const unsigned long      nlm_timeout_min = 3;
static const unsigned long      nlm_timeout_max = 20;
static const int                nlm_port_min = 0, nlm_port_max = 65535;

static struct ctl_table_header * nlm_sysctl_table;

static unsigned long set_grace_period(void)
{
        unsigned long grace_period;

        /* Note: nlm_timeout should always be nonzero */
        if (nlm_grace_period)
                grace_period = ((nlm_grace_period + nlm_timeout - 1)
                                / nlm_timeout) * nlm_timeout * HZ;
        else
                grace_period = nlm_timeout * 5 * HZ;
        nlmsvc_grace_period = 1;
        return grace_period + jiffies;
}

static inline void clear_grace_period(void)
{
        nlmsvc_grace_period = 0;
}

/*
 * This is the lockd kernel thread
 */
static void
lockd(struct svc_rqst *rqstp)
{
        int             err = 0;
        unsigned long grace_period_expire;

        /* Lock module and set up kernel thread */
        /* lockd_up is waiting for us to startup, so will
         * be holding a reference to this module, so it
         * is safe to just claim another reference
         */
        __module_get(THIS_MODULE);
        lock_kernel();

        /*
         * Let our maker know we're running.
         */
        nlmsvc_pid = current->pid;
        nlmsvc_serv = rqstp->rq_server;
        complete(&lockd_start_done);

        daemonize("lockd");
        set_freezable();

        /* Process request with signals blocked, but allow SIGKILL.  */
        allow_signal(SIGKILL);

        dprintk("NFS locking service started (ver " LOCKD_VERSION ").\n");

        if (!nlm_timeout)
                nlm_timeout = LOCKD_DFLT_TIMEO;
        nlmsvc_timeout = nlm_timeout * HZ;

        grace_period_expire = set_grace_period();

        /*
         * The main request loop. We don't terminate until the last
         * NFS mount or NFS daemon has gone away, and we've been sent a
         * signal, or else another process has taken over our job.
         */
        while ((nlmsvc_users || !signalled()) && nlmsvc_pid == current->pid) {
                long timeout = MAX_SCHEDULE_TIMEOUT;
                char buf[RPC_MAX_ADDRBUFLEN];

                if (signalled()) {
                        flush_signals(current);
                        if (nlmsvc_ops) {
                                nlmsvc_invalidate_all();
                                grace_period_expire = set_grace_period();
                        }
                }

                /*
                 * Retry any blocked locks that have been notified by
                 * the VFS. Don't do this during grace period.
                 * (Theoretically, there shouldn't even be blocked locks
                 * during grace period).
                 */
                if (!nlmsvc_grace_period) {
                        timeout = nlmsvc_retry_blocked();
                } else if (time_before(grace_period_expire, jiffies))
                        clear_grace_period();

                /*
                 * Find a socket with data available and call its
                 * recvfrom routine.
                 */
                err = svc_recv(rqstp, timeout);
                if (err == -EAGAIN || err == -EINTR)
                        continue;
                if (err < 0) {
                        printk(KERN_WARNING
                               "lockd: terminating on error %d\n",
                               -err);
                        break;
                }

                dprintk("lockd: request from %s\n",
                                svc_print_addr(rqstp, buf, sizeof(buf)));

                svc_process(rqstp);
        }

        flush_signals(current);

        /*
         * Check whether there's a new lockd process before
         * shutting down the hosts and clearing the slot.
         */
        if (!nlmsvc_pid || current->pid == nlmsvc_pid) {
                if (nlmsvc_ops)
                        nlmsvc_invalidate_all();
                nlm_shutdown_hosts();
                nlmsvc_pid = 0;
                nlmsvc_serv = NULL;
        } else
                printk(KERN_DEBUG
                        "lockd: new process, skipping host shutdown\n");
        wake_up(&lockd_exit);

        /* Exit the RPC thread */
        svc_exit_thread(rqstp);

        /* Release module */
        unlock_kernel();
        module_put_and_exit(0);
}


static int find_socket(struct svc_serv *serv, int proto)
{
        struct svc_sock *svsk;
        int found = 0;
        list_for_each_entry(svsk, &serv->sv_permsocks, sk_list)
                if (svsk->sk_sk->sk_protocol == proto) {
                        found = 1;
                        break;
                }
        return found;
}

/*
 * Make any sockets that are needed but not present.
 * If nlm_udpport or nlm_tcpport were set as module
 * options, make those sockets unconditionally
 */
static int make_socks(struct svc_serv *serv, int proto)
{
        static int warned;
        int err = 0;

        if (proto == IPPROTO_UDP || nlm_udpport)
                if (!find_socket(serv, IPPROTO_UDP))
                        err = svc_makesock(serv, IPPROTO_UDP, nlm_udpport,
                                                SVC_SOCK_DEFAULTS);
        if (err >= 0 && (proto == IPPROTO_TCP || nlm_tcpport))
                if (!find_socket(serv, IPPROTO_TCP))
                        err = svc_makesock(serv, IPPROTO_TCP, nlm_tcpport,
                                                SVC_SOCK_DEFAULTS);

        if (err >= 0) {
                warned = 0;
                err = 0;
        } else if (warned++ == 0)
                printk(KERN_WARNING
                       "lockd_up: makesock failed, error=%d\n", err);
        return err;
}

/*
 * Bring up the lockd process if it's not already up.
 */
int
lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */
{
        struct svc_serv *       serv;
        int                     error = 0;

        mutex_lock(&nlmsvc_mutex);
        /*
         * Check whether we're already up and running.
         */
        if (nlmsvc_pid) {
                if (proto)
                        error = make_socks(nlmsvc_serv, proto);
                goto out;
        }

        /*
         * Sanity check: if there's no pid,
         * we should be the first user ...
         */
        if (nlmsvc_users)
                printk(KERN_WARNING
                        "lockd_up: no pid, %d users??\n", nlmsvc_users);

        error = -ENOMEM;
        serv = svc_create(&nlmsvc_program, LOCKD_BUFSIZE, NULL);
        if (!serv) {
                printk(KERN_WARNING "lockd_up: create service failed\n");
                goto out;
        }

        if ((error = make_socks(serv, proto)) < 0)
                goto destroy_and_out;

        /*
         * Create the kernel thread and wait for it to start.
         */
        error = svc_create_thread(lockd, serv);
        if (error) {
                printk(KERN_WARNING
                        "lockd_up: create thread failed, error=%d\n", error);
                goto destroy_and_out;
        }
        wait_for_completion(&lockd_start_done);

        /*
         * Note: svc_serv structures have an initial use count of 1,
         * so we exit through here on both success and failure.
         */
destroy_and_out:
        svc_destroy(serv);
out:
        if (!error)
                nlmsvc_users++;
        mutex_unlock(&nlmsvc_mutex);
        return error;
}
EXPORT_SYMBOL(lockd_up);

/*
 * Decrement the user count and bring down lockd if we're the last.
 */
void
lockd_down(void)
{
        static int warned;

        mutex_lock(&nlmsvc_mutex);
        if (nlmsvc_users) {
                if (--nlmsvc_users)
                        goto out;
        } else
                printk(KERN_WARNING "lockd_down: no users! pid=%d\n", nlmsvc_pid);

        if (!nlmsvc_pid) {
                if (warned++ == 0)
                        printk(KERN_WARNING "lockd_down: no lockd running.\n"); 
                goto out;
        }
        warned = 0;

        kill_proc(nlmsvc_pid, SIGKILL, 1);
        /*
         * Wait for the lockd process to exit, but since we're holding
         * the lockd semaphore, we can't wait around forever ...
         */
        clear_thread_flag(TIF_SIGPENDING);
        interruptible_sleep_on_timeout(&lockd_exit, HZ);
        if (nlmsvc_pid) {
                printk(KERN_WARNING 
                        "lockd_down: lockd failed to exit, clearing pid\n");
                nlmsvc_pid = 0;
        }
        spin_lock_irq(&current->sighand->siglock);
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);
out:
        mutex_unlock(&nlmsvc_mutex);
}
EXPORT_SYMBOL(lockd_down);

/*
 * Sysctl parameters (same as module parameters, different interface).
 */

static ctl_table nlm_sysctls[] = {
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "nlm_grace_period",
                .data           = &nlm_grace_period,
                .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
                .proc_handler   = &proc_doulongvec_minmax,
                .extra1         = (unsigned long *) &nlm_grace_period_min,
                .extra2         = (unsigned long *) &nlm_grace_period_max,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "nlm_timeout",
                .data           = &nlm_timeout,
                .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
                .proc_handler   = &proc_doulongvec_minmax,
                .extra1         = (unsigned long *) &nlm_timeout_min,
                .extra2         = (unsigned long *) &nlm_timeout_max,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "nlm_udpport",
                .data           = &nlm_udpport,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec_minmax,
                .extra1         = (int *) &nlm_port_min,
                .extra2         = (int *) &nlm_port_max,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "nlm_tcpport",
                .data           = &nlm_tcpport,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec_minmax,
                .extra1         = (int *) &nlm_port_min,
                .extra2         = (int *) &nlm_port_max,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "nsm_use_hostnames",
                .data           = &nsm_use_hostnames,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "nsm_local_state",
                .data           = &nsm_local_state,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
        },
        { .ctl_name = 0 }
};

static ctl_table nlm_sysctl_dir[] = {
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "nfs",
                .mode           = 0555,
                .child          = nlm_sysctls,
        },
        { .ctl_name = 0 }
};

static ctl_table nlm_sysctl_root[] = {
        {
                .ctl_name       = CTL_FS,
                .procname       = "fs",
                .mode           = 0555,
                .child          = nlm_sysctl_dir,
        },
        { .ctl_name = 0 }
};

/*
 * Module (and sysfs) parameters.
 */

#define param_set_min_max(name, type, which_strtol, min, max)           \
static int param_set_##name(const char *val, struct kernel_param *kp)   \
{                                                                       \
        char *endp;                                                     \
        __typeof__(type) num = which_strtol(val, &endp, 0);             \
        if (endp == val || *endp || num < (min) || num > (max))         \
                return -EINVAL;                                         \
        *((int *) kp->arg) = num;                                       \
        return 0;                                                       \
}

static inline int is_callback(u32 proc)
{
        return proc == NLMPROC_GRANTED
                || proc == NLMPROC_GRANTED_MSG
                || proc == NLMPROC_TEST_RES
                || proc == NLMPROC_LOCK_RES
                || proc == NLMPROC_CANCEL_RES
                || proc == NLMPROC_UNLOCK_RES
                || proc == NLMPROC_NSM_NOTIFY;
}


static int lockd_authenticate(struct svc_rqst *rqstp)
{
        rqstp->rq_client = NULL;
        switch (rqstp->rq_authop->flavour) {
                case RPC_AUTH_NULL:
                case RPC_AUTH_UNIX:
                        if (rqstp->rq_proc == 0)
                                return SVC_OK;
                        if (is_callback(rqstp->rq_proc)) {
                                /* Leave it to individual procedures to
                                 * call nlmsvc_lookup_host(rqstp)
                                 */
                                return SVC_OK;
                        }
                        return svc_set_client(rqstp);
        }
        return SVC_DENIED;
}


param_set_min_max(port, int, simple_strtol, 0, 65535)
param_set_min_max(grace_period, unsigned long, simple_strtoul,
                  nlm_grace_period_min, nlm_grace_period_max)
param_set_min_max(timeout, unsigned long, simple_strtoul,
                  nlm_timeout_min, nlm_timeout_max)

MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
MODULE_DESCRIPTION("NFS file locking service version " LOCKD_VERSION ".");
MODULE_LICENSE("GPL");

module_param_call(nlm_grace_period, param_set_grace_period, param_get_ulong,
                  &nlm_grace_period, 0644);
module_param_call(nlm_timeout, param_set_timeout, param_get_ulong,
                  &nlm_timeout, 0644);
module_param_call(nlm_udpport, param_set_port, param_get_int,
                  &nlm_udpport, 0644);
module_param_call(nlm_tcpport, param_set_port, param_get_int,
                  &nlm_tcpport, 0644);
module_param(nsm_use_hostnames, bool, 0644);

/*
 * Initialising and terminating the module.
 */

static int __init init_nlm(void)
{
        nlm_sysctl_table = register_sysctl_table(nlm_sysctl_root);
        return nlm_sysctl_table ? 0 : -ENOMEM;
}

static void __exit exit_nlm(void)
{
        /* FIXME: delete all NLM clients */
        nlm_shutdown_hosts();
        unregister_sysctl_table(nlm_sysctl_table);
}

module_init(init_nlm);
module_exit(exit_nlm);

/*
 * Define NLM program and procedures
 */
static struct svc_version       nlmsvc_version1 = {
                .vs_vers        = 1,
                .vs_nproc       = 17,
                .vs_proc        = nlmsvc_procedures,
                .vs_xdrsize     = NLMSVC_XDRSIZE,
};
static struct svc_version       nlmsvc_version3 = {
                .vs_vers        = 3,
                .vs_nproc       = 24,
                .vs_proc        = nlmsvc_procedures,
                .vs_xdrsize     = NLMSVC_XDRSIZE,
};
#ifdef CONFIG_LOCKD_V4
static struct svc_version       nlmsvc_version4 = {
                .vs_vers        = 4,
                .vs_nproc       = 24,
                .vs_proc        = nlmsvc_procedures4,
                .vs_xdrsize     = NLMSVC_XDRSIZE,
};
#endif
static struct svc_version *     nlmsvc_version[] = {
        [1] = &nlmsvc_version1,
        [3] = &nlmsvc_version3,
#ifdef CONFIG_LOCKD_V4
        [4] = &nlmsvc_version4,
#endif
};

static struct svc_stat          nlmsvc_stats;

#define NLM_NRVERS      ARRAY_SIZE(nlmsvc_version)
static struct svc_program       nlmsvc_program = {
        .pg_prog                = NLM_PROGRAM,          /* program number */
        .pg_nvers               = NLM_NRVERS,           /* number of entries in nlmsvc_version */
        .pg_vers                = nlmsvc_version,       /* version table */
        .pg_name                = "lockd",              /* service name */
        .pg_class               = "nfsd",               /* share authentication with nfsd */
        .pg_stats               = &nlmsvc_stats,        /* stats table */
        .pg_authenticate = &lockd_authenticate  /* export authentication */
};