cregit-Linux how code gets into the kernel

Release 4.11 net/sunrpc/svc_xprt.c

Directory: net/sunrpc
/*
 * linux/net/sunrpc/svc_xprt.c
 *
 * Author: Tom Tucker <tom@opengridcomputing.com>
 */

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/sunrpc/addr.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/svc_xprt.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/xprt.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <trace/events/sunrpc.h>


#define RPCDBG_FACILITY	RPCDBG_SVCXPRT


static unsigned int svc_rpc_per_connection_limit __read_mostly;
module_param(svc_rpc_per_connection_limit, uint, 0644);


static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt);
static int svc_deferred_recv(struct svc_rqst *rqstp);
static struct cache_deferred_req *svc_defer(struct cache_req *req);
static void svc_age_temp_xprts(unsigned long closure);
static void svc_delete_xprt(struct svc_xprt *xprt);

/* apparently the "standard" is that clients close
 * idle connections after 5 minutes, servers after
 * 6 minutes
 *   http://www.connectathon.org/talks96/nfstcp.pdf
 */

static int svc_conn_age_period = 6*60;

/* List of registered transport classes */
static DEFINE_SPINLOCK(svc_xprt_class_lock);
static LIST_HEAD(svc_xprt_class_list);

/* SMP locking strategy:
 *
 *      svc_pool->sp_lock protects most of the fields of that pool.
 *      svc_serv->sv_lock protects sv_tempsocks, sv_permsocks, sv_tmpcnt.
 *      when both need to be taken (rare), svc_serv->sv_lock is first.
 *      The "service mutex" protects svc_serv->sv_nrthread.
 *      svc_sock->sk_lock protects the svc_sock->sk_deferred list
 *             and the ->sk_info_authunix cache.
 *
 *      The XPT_BUSY bit in xprt->xpt_flags prevents a transport being
 *      enqueued multiply. During normal transport processing this bit
 *      is set by svc_xprt_enqueue and cleared by svc_xprt_received.
 *      Providers should not manipulate this bit directly.
 *
 *      Some flags can be set to certain values at any time
 *      providing that certain rules are followed:
 *
 *      XPT_CONN, XPT_DATA:
 *              - Can be set or cleared at any time.
 *              - After a set, svc_xprt_enqueue must be called to enqueue
 *                the transport for processing.
 *              - After a clear, the transport must be read/accepted.
 *                If this succeeds, it must be set again.
 *      XPT_CLOSE:
 *              - Can set at any time. It is never cleared.
 *      XPT_DEAD:
 *              - Can only be set while XPT_BUSY is held which ensures
 *                that no other thread will be using the transport or will
 *                try to set XPT_DEAD.
 */



int svc_reg_xprt_class(struct svc_xprt_class *xcl)
{
	struct svc_xprt_class *cl;
	int res = -EEXIST;

	dprintk("svc: Adding svc transport class '%s'\n", xcl->xcl_name);

	INIT_LIST_HEAD(&xcl->xcl_list);
	spin_lock(&svc_xprt_class_lock);
	/* Make sure there isn't already a class with the same name */
	list_for_each_entry(cl, &svc_xprt_class_list, xcl_list) {
		if (strcmp(xcl->xcl_name, cl->xcl_name) == 0)
			goto out;
	}
	list_add_tail(&xcl->xcl_list, &svc_xprt_class_list);
	res = 0;
out:
	spin_unlock(&svc_xprt_class_lock);
	return res;
}

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EXPORT_SYMBOL_GPL(svc_reg_xprt_class);




void svc_unreg_xprt_class(struct svc_xprt_class *xcl)
{
	dprintk("svc: Removing svc transport class '%s'\n", xcl->xcl_name);
	spin_lock(&svc_xprt_class_lock);
	list_del_init(&xcl->xcl_list);
	spin_unlock(&svc_xprt_class_lock);
}

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EXPORT_SYMBOL_GPL(svc_unreg_xprt_class);

/*
 * Format the transport list for printing
 */



int svc_print_xprts(char *buf, int maxlen)
{
	struct svc_xprt_class *xcl;
	char tmpstr[80];
	int len = 0;
	buf[0] = '\0';

	spin_lock(&svc_xprt_class_lock);
	list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
		int slen;

		sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
		slen = strlen(tmpstr);
		if (len + slen > maxlen)
			break;
		len += slen;
		strcat(buf, tmpstr);
	}
	spin_unlock(&svc_xprt_class_lock);

	return len;
}


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static void svc_xprt_free(struct kref *kref)
{
	struct svc_xprt *xprt =
		container_of(kref, struct svc_xprt, xpt_ref);
	struct module *owner = xprt->xpt_class->xcl_owner;
	if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags))
		svcauth_unix_info_release(xprt);
	put_net(xprt->xpt_net);
	/* See comment on corresponding get in xs_setup_bc_tcp(): */
	if (xprt->xpt_bc_xprt)
		xprt_put(xprt->xpt_bc_xprt);
	if (xprt->xpt_bc_xps)
		xprt_switch_put(xprt->xpt_bc_xps);
	xprt->xpt_ops->xpo_free(xprt);
	module_put(owner);
}


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void svc_xprt_put(struct svc_xprt *xprt)
{
	kref_put(&xprt->xpt_ref, svc_xprt_free);
}

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EXPORT_SYMBOL_GPL(svc_xprt_put);

/*
 * Called by transport drivers to initialize the transport independent
 * portion of the transport instance.
 */



void svc_xprt_init(struct net *net, struct svc_xprt_class *xcl,
		   struct svc_xprt *xprt, struct svc_serv *serv)
{
	memset(xprt, 0, sizeof(*xprt));
	xprt->xpt_class = xcl;
	xprt->xpt_ops = xcl->xcl_ops;
	kref_init(&xprt->xpt_ref);
	xprt->xpt_server = serv;
	INIT_LIST_HEAD(&xprt->xpt_list);
	INIT_LIST_HEAD(&xprt->xpt_ready);
	INIT_LIST_HEAD(&xprt->xpt_deferred);
	INIT_LIST_HEAD(&xprt->xpt_users);
	mutex_init(&xprt->xpt_mutex);
	spin_lock_init(&xprt->xpt_lock);
	set_bit(XPT_BUSY, &xprt->xpt_flags);
	rpc_init_wait_queue(&xprt->xpt_bc_pending, "xpt_bc_pending");
	xprt->xpt_net = get_net(net);
}

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Stanislav Kinsbursky64.20%18.33%


Total143100.00%12100.00%




EXPORT_SYMBOL_GPL(svc_xprt_init);




static struct svc_xprt *__svc_xpo_create(struct svc_xprt_class *xcl,
					 struct svc_serv *serv,
					 struct net *net,
					 const int family,
					 const unsigned short port,
					 int flags)
{
	struct sockaddr_in sin = {
		.sin_family		= AF_INET,
		.sin_addr.s_addr	= htonl(INADDR_ANY),
		.sin_port		= htons(port),
        };
#if IS_ENABLED(CONFIG_IPV6)
	struct sockaddr_in6 sin6 = {
		.sin6_family		= AF_INET6,
		.sin6_addr		= IN6ADDR_ANY_INIT,
		.sin6_port		= htons(port),
        };
#endif
	struct sockaddr *sap;
	size_t len;

	switch (family) {
	case PF_INET:
		sap = (struct sockaddr *)&sin;
		len = sizeof(sin);
		break;
#if IS_ENABLED(CONFIG_IPV6)
	case PF_INET6:
		sap = (struct sockaddr *)&sin6;
		len = sizeof(sin6);
		break;
#endif
	default:
		return ERR_PTR(-EAFNOSUPPORT);
	}

	return xcl->xcl_ops->xpo_create(serv, net, sap, len, flags);
}


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Eric Dumazet21.08%114.29%


Total186100.00%7100.00%



/*
 * svc_xprt_received conditionally queues the transport for processing
 * by another thread. The caller must hold the XPT_BUSY bit and must
 * not thereafter touch transport data.
 *
 * Note: XPT_DATA only gets cleared when a read-attempt finds no (or
 * insufficient) data.
 */



static void svc_xprt_received(struct svc_xprt *xprt)
{
	if (!test_bit(XPT_BUSY, &xprt->xpt_flags)) {
		WARN_ONCE(1, "xprt=0x%p already busy!", xprt);
		return;
	}

	/* As soon as we clear busy, the xprt could be closed and
         * 'put', so we need a reference to call svc_enqueue_xprt with:
         */
	svc_xprt_get(xprt);
	smp_mb__before_atomic();
	clear_bit(XPT_BUSY, &xprt->xpt_flags);
	xprt->xpt_server->sv_ops->svo_enqueue_xprt(xprt);
	svc_xprt_put(xprt);
}


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Total71100.00%5100.00%






void svc_add_new_perm_xprt(struct svc_serv *serv, struct svc_xprt *new)
{
	clear_bit(XPT_TEMP, &new->xpt_flags);
	spin_lock_bh(&serv->sv_lock);
	list_add(&new->xpt_list, &serv->sv_permsocks);
	spin_unlock_bh(&serv->sv_lock);
	svc_xprt_received(new);
}


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int _svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
		    struct net *net, const int family,
		    const unsigned short port, int flags)
{
	struct svc_xprt_class *xcl;

	spin_lock(&svc_xprt_class_lock);
	list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
		struct svc_xprt *newxprt;
		unsigned short newport;

		if (strcmp(xprt_name, xcl->xcl_name))
			continue;

		if (!try_module_get(xcl->xcl_owner))
			goto err;

		spin_unlock(&svc_xprt_class_lock);
		newxprt = __svc_xpo_create(xcl, serv, net, family, port, flags);
		if (IS_ERR(newxprt)) {
			module_put(xcl->xcl_owner);
			return PTR_ERR(newxprt);
		}
		svc_add_new_perm_xprt(serv, newxprt);
		newport = svc_xprt_local_port(newxprt);
		return newport;
	}
 err:
	spin_unlock(&svc_xprt_class_lock);
	/* This errno is exposed to user space.  Provide a reasonable
         * perror msg for a bad transport. */
	return -EPROTONOSUPPORT;
}


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Pavel Emelyanov74.32%220.00%


Total162100.00%10100.00%






int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
		    struct net *net, const int family,
		    const unsigned short port, int flags)
{
	int err;

	dprintk("svc: creating transport %s[%d]\n", xprt_name, port);
	err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
	if (err == -EPROTONOSUPPORT) {
		request_module("svc%s", xprt_name);
		err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
	}
	if (err)
		dprintk("svc: transport %s not found, err %d\n",
			xprt_name, err);
	return err;
}

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EXPORT_SYMBOL_GPL(svc_create_xprt);

/*
 * Copy the local and remote xprt addresses to the rqstp structure
 */



void svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt)
{
	memcpy(&rqstp->rq_addr, &xprt->xpt_remote, xprt->xpt_remotelen);
	rqstp->rq_addrlen = xprt->xpt_remotelen;

	/*
         * Destination address in request is needed for binding the
         * source address in RPC replies/callbacks later.
         */
	memcpy(&rqstp->rq_daddr, &xprt->xpt_local, xprt->xpt_locallen);
	rqstp->rq_daddrlen = xprt->xpt_locallen;
}

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EXPORT_SYMBOL_GPL(svc_xprt_copy_addrs);

/**
 * svc_print_addr - Format rq_addr field for printing
 * @rqstp: svc_rqst struct containing address to print
 * @buf: target buffer for formatted address
 * @len: length of target buffer
 *
 */



char *svc_print_addr(struct svc_rqst *rqstp, char *buf, size_t len)
{
	return __svc_print_addr(svc_addr(rqstp), buf, len);
}

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EXPORT_SYMBOL_GPL(svc_print_addr);




static bool svc_xprt_slots_in_range(struct svc_xprt *xprt)
{
	unsigned int limit = svc_rpc_per_connection_limit;
	int nrqsts = atomic_read(&xprt->xpt_nr_rqsts);

	return limit == 0 || (nrqsts >= 0 && nrqsts < limit);
}


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static bool svc_xprt_reserve_slot(struct svc_rqst *rqstp, struct svc_xprt *xprt)
{
	if (!test_bit(RQ_DATA, &rqstp->rq_flags)) {
		if (!svc_xprt_slots_in_range(xprt))
			return false;
		atomic_inc(&xprt->xpt_nr_rqsts);
		set_bit(RQ_DATA, &rqstp->rq_flags);
	}
	return true;
}


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static void svc_xprt_release_slot(struct svc_rqst *rqstp)
{
	struct svc_xprt	*xprt = rqstp->rq_xprt;
	if (test_and_clear_bit(RQ_DATA, &rqstp->rq_flags)) {
		atomic_dec(&xprt->xpt_nr_rqsts);
		svc_xprt_enqueue(xprt);
	}
}


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static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
{
	if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
		return true;
	if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED))) {
		if (xprt->xpt_ops->xpo_has_wspace(xprt) &&
		    svc_xprt_slots_in_range(xprt))
			return true;
		trace_svc_xprt_no_write_space(xprt);
		return false;
	}
	return false;
}


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void svc_xprt_do_enqueue(struct svc_xprt *xprt)
{
	struct svc_pool *pool;
	struct svc_rqst	*rqstp = NULL;
	int cpu;
	bool queued = false;

	if (!svc_xprt_has_something_to_do(xprt))
		goto out;

	/* Mark transport as busy. It will remain in this state until
         * the provider calls svc_xprt_received. We update XPT_BUSY
         * atomically because it also guards against trying to enqueue
         * the transport twice.
         */
	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags)) {
		/* Don't enqueue transport while already enqueued */
		dprintk("svc: transport %p busy, not enqueued\n", xprt);
		goto out;
	}

	cpu = get_cpu();
	pool = svc_pool_for_cpu(xprt->xpt_server, cpu);

	atomic_long_inc(&pool->sp_stats.packets);

redo_search:
	/* find a thread for this xprt */
	rcu_read_lock();
	list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
		/* Do a lockless check first */
		if (test_bit(RQ_BUSY, &rqstp->rq_flags))
			continue;

		/*
                 * Once the xprt has been queued, it can only be dequeued by
                 * the task that intends to service it. All we can do at that
                 * point is to try to wake this thread back up so that it can
                 * do so.
                 */
		if (!queued) {
			spin_lock_bh(&rqstp->rq_lock);
			if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) {
				/* already busy, move on... */
				spin_unlock_bh(&rqstp->rq_lock);
				continue;
			}

			/* this one will do */
			rqstp->rq_xprt = xprt;
			svc_xprt_get(xprt);
			spin_unlock_bh(&rqstp->rq_lock);
		}
		rcu_read_unlock();

		atomic_long_inc(&pool->sp_stats.threads_woken);
		wake_up_process(rqstp->rq_task);
		put_cpu();
		goto out;
	}
	rcu_read_unlock();

	/*
         * We didn't find an idle thread to use, so we need to queue the xprt.
         * Do so and then search again. If we find one, we can't hook this one
         * up to it directly but we can wake the thread up in the hopes that it
         * will pick it up once it searches for a xprt to service.
         */
	if (!queued) {
		queued = true;
		dprintk("svc: transport %p put into queue\n", xprt);
		spin_lock_bh(&pool->sp_lock);
		list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
		pool->sp_stats.sockets_queued++;
		spin_unlock_bh(&pool->sp_lock);
		goto redo_search;
	}
	rqstp = NULL;
	put_cpu();
out:
	trace_svc_xprt_do_enqueue(xprt, rqstp);
}

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Total286100.00%10100.00%




EXPORT_SYMBOL_GPL(svc_xprt_do_enqueue);

/*
 * Queue up a transport with data pending. If there are idle nfsd
 * processes, wake 'em up.
 *
 */



void svc_xprt_enqueue(struct svc_xprt *xprt)
{
	if (test_bit(XPT_BUSY, &xprt->xpt_flags))
		return;
	xprt->xpt_server->sv_ops->svo_enqueue_xprt(xprt);
}

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EXPORT_SYMBOL_GPL(svc_xprt_enqueue);

/*
 * Dequeue the first transport, if there is one.
 */



static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool)
{
	struct svc_xprt	*xprt = NULL;

	if (list_empty(&pool->sp_sockets))
		goto out;

	spin_lock_bh(&pool->sp_lock);
	if (likely(!list_empty(&pool->sp_sockets))) {
		xprt = list_first_entry(&pool->sp_sockets,
					struct svc_xprt, xpt_ready);
		list_del_init(&xprt->xpt_ready);
		svc_xprt_get(xprt);

		dprintk("svc: transport %p dequeued, inuse=%d\n",
			xprt, kref_read(&xprt->xpt_ref));
	}
	spin_unlock_bh(&pool->sp_lock);
out:
	trace_svc_xprt_dequeue(xprt);
	return xprt;
}


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/**
 * svc_reserve - change the space reserved for the reply to a request.
 * @rqstp:  The request in question
 * @space: new max space to reserve
 *
 * Each request reserves some space on the output queue of the transport
 * to make sure the reply fits.  This function reduces that reserved
 * space to be the amount of space used already, plus @space.
 *
 */



void svc_reserve(struct svc_rqst *rqstp, int space)
{
	space += rqstp->rq_res.head[0].iov_len;

	if (space < rqstp->rq_reserved) {
		struct svc_xprt *xprt = rqstp->rq_xprt;
		atomic_sub((rqstp->rq_reserved - space), &xprt->xpt_reserved);
		rqstp->rq_reserved = space;

		svc_xprt_enqueue(xprt);
	}
}

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EXPORT_SYMBOL_GPL(svc_reserve);




static void svc_xprt_release(struct svc_rqst *rqstp)
{
	struct svc_xprt	*xprt = rqstp->rq_xprt;

	rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);

	kfree(rqstp->rq_deferred);
	rqstp->rq_deferred = NULL;

	svc_free_res_pages(rqstp);
	rqstp->rq_res.page_len = 0;
	rqstp->rq_res.page_base = 0;

	/* Reset response buffer and release
         * the reservation.
         * But first, check that enough space was reserved
         * for the reply, otherwise we have a bug!
         */
	if ((rqstp->rq_res.len) >  rqstp->rq_reserved)
		printk(KERN_ERR "RPC request reserved %d but used %d\n",
		       rqstp->rq_reserved,
		       rqstp->rq_res.len);

	rqstp->rq_res.head[0].iov_len = 0;
	svc_reserve(rqstp, 0);
	svc_xprt_release_slot(rqstp);
	rqstp->rq_xprt = NULL;
	svc_xprt_put(xprt);
}


Contributors
PersonTokensPropCommitsCommitProp
Tom Tucker12796.21%266.67%


Trond Myklebust53.79%133.33%


Total132100.00%3100.00%



/*
 * Some svc_serv's will have occasional work to do, even when a xprt is not
 * waiting to be serviced. This function is there to "kick" a task in one of
 * those services so that it can wake up and do that work. Note that we only
 * bother with pool 0 as we don't need to wake up more than one thread for
 * this purpose.
 */



void svc_wake_up(struct svc_serv *serv)
{
	struct svc_rqst	*rqstp;
	struct svc_pool *pool;

	pool = &serv->sv_pools[0];

	rcu_read_lock();
	list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
		/* skip any that aren't queued */
		if (test_bit(RQ_BUSY, &rqstp->rq_flags))
			continue;
		rcu_read_unlock();
		dprintk("svc: daemon %p woken up.\n", rqstp);
		wake_up_process(rqstp->rq_task);
		trace_svc_wake_up(rqstp->rq_task->pid);
		return;
	}
	rcu_read_unlock();

	/* No free entries available */
	set_bit(SP_TASK_PENDING, &pool->sp_flags);
	smp_wmb();
	trace_svc_wake_up(0);
}

Contributors
PersonTokensPropCommitsCommitProp
Tom Tucker5350.00%114.29%


Jeff Layton4845.28%457.14%


Andriy Skulysh32.83%114.29%


Trond Myklebust21.89%114.29%


Total106100.00%7100.00%




EXPORT_SYMBOL_GPL(svc_wake_up);




int svc_port_is_privileged(struct sockaddr *sin)
{
	switch (sin->sa_family) {
	case AF_INET:
		return ntohs(((struct sockaddr_in *)sin)->sin_port)
			< PROT_SOCK;
	case AF_INET6:
		return ntohs(((struct sockaddr_in6 *)sin)->sin6_port)
			< PROT_SOCK;
	default:
		return 0;
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Tom Tucker62100.00%1100.00%


Total62100.00%1100.00%



/*
 * Make sure that we don't have too many active connections. If we have,
 * something must be dropped. It's not clear what will happen if we allow
 * "too many" connections, but when dealing with network-facing software,
 * we have to code defensively. Here we do that by imposing hard limits.
 *
 * There's no point in trying to do random drop here for DoS
 * prevention. The NFS clients does 1 reconnect in 15 seconds. An
 * attacker can easily beat that.
 *
 * The only somewhat efficient mechanism would be if drop old
 * connections from the same IP first. But right now we don't even
 * record the client IP in svc_sock.
 *
 * single-threaded services that expect a lot of clients will probably
 * need to set sv_maxconn to override the default value which is based
 * on the number of threads
 */



static void svc_check_conn_limits(struct svc_serv *serv)
{
	unsigned int limit = serv->sv_maxconn ? serv->sv_maxconn :
				(serv->sv_nrthreads+3) * 20;

	if (serv->sv_tmpcnt > limit) {
		struct svc_xprt *xprt = NULL;
		spin_lock_bh(&serv->sv_lock);
		if (!list_empty(&serv->sv_tempsocks)) {
			/* Try to help the admin */
			net_notice_ratelimited("%s: too many open connections, consider increasing the %s\n",
					       serv->sv_name, serv->sv_maxconn ?
					       "max number of connections" :
					       "number of threads");
			/*
                         * Always select the oldest connection. It's not fair,
                         * but so is life
                         */
			xprt = list_entry(serv->sv_tempsocks.prev,
					  struct svc_xprt,
					  xpt_list);
			set_bit(XPT_CLOSE, &xprt->xpt_flags);
			svc_xprt_get(xprt);
		}
		spin_unlock_bh(&serv->sv_lock);

		if (xprt) {
			svc_xprt_enqueue(xprt);
			svc_xprt_put(xprt);
		}
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Tom Tucker11780.69%133.33%


Jeff Layton2416.55%133.33%


Joe Perches42.76%133.33%


Total145100.00%3100.00%






static int svc_alloc_arg(struct svc_rqst *rqstp)
{
	struct svc_serv *serv = rqstp->rq_server;
	struct xdr_buf *arg;
	int pages;
	int i;

	/* now allocate needed pages.  If we get a failure, sleep briefly */
	pages = (serv->sv_max_mesg + PAGE_SIZE) / PAGE_SIZE;
	WARN_ON_ONCE(pages >= RPCSVC_MAXPAGES);
	if (pages >= RPCSVC_MAXPAGES)
		/* use as many pages as possible */
		pages = RPCSVC_MAXPAGES - 1;
	for (i = 0; i < pages ; i++)
		while (rqstp->rq_pages[i] == NULL) {
			struct page *p = alloc_page(GFP_KERNEL);
			if (!p) {
				set_current_state(TASK_INTERRUPTIBLE);
				if (signalled() || kthread_should_stop()) {
					set_current_state(TASK_RUNNING);
					return -EINTR;
				}
				schedule_timeout(msecs_to_jiffies(500));
			}
			rqstp->rq_pages[i] = p;
		}
	rqstp->rq_page_end = &rqstp->rq_pages[i];
	rqstp->rq_pages[i++] = NULL; /* this might be seen in nfs_read_actor */

	/* Make arg->head point to first page and arg->pages point to rest */
	arg = &rqstp->rq_arg;
	arg->head[0].iov_base = page_address(rqstp->rq_pages[0]);
	arg->head[0].iov_len = PAGE_SIZE;
	arg->pages = rqstp->rq_pages + 1;
	arg->page_base = 0;
	/* save at least one page for response */
	arg->page_len = (pages-2)*PAGE_SIZE;
	arg->len = (pages-1)*PAGE_SIZE;
	arg->tail[0].iov_len = 0;
	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Tom Tucker19674.24%111.11%


Jeff Layton3312.50%333.33%


J. Bruce Fields197.20%222.22%


Weston Andros Adamson145.30%111.11%


Rashika Kheria10.38%111.11%


Greg Banks10.38%111.11%


Total264100.00%9100.00%





static bool

rqst_should_sleep(struct svc_rqst *rqstp)
{
	struct svc_pool		*pool = rqstp->rq_pool;

	/* did someone call svc_wake_up? */
	if (test_and_clear_bit(SP_TASK_PENDING, &pool->sp_flags))
		return false;

	/* was a socket queued? */
	if (!list_empty(&pool->sp_sockets))
		return false;

	/* are we shutting down? */
	if (signalled() || kthread_should_stop())
		return false;

	/* are we freezing? */
	if (freezing(current))
		return false;

	return true;
}


Contributors
PersonTokensPropCommitsCommitProp
Jeff Layton77100.00%1100.00%


Total77100.00%1100.00%






static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
{
	struct svc_xprt *xprt;
	struct svc_pool		*pool = rqstp->rq_pool;