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svc_xprt.c
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/*
* linux/net/sunrpc/svc_xprt.c
*
* Author: Tom Tucker <[email protected]>
*/
#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;
}
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);
}
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;
}
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);
}
void svc_xprt_put(struct svc_xprt *xprt)
{
kref_put(&xprt->xpt_ref, svc_xprt_free);
}
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);
}
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);
}
/*
* 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);
}
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);
}
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;
}
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;
}
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;
}
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);
}
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);
}
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;
}
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);
}
}
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;
}
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);
}
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);
}
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, atomic_read(&xprt->xpt_ref.refcount));
}
spin_unlock_bh(&pool->sp_lock);
out:
trace_svc_xprt_dequeue(xprt);
return xprt;
}
/**
* 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);
}
}
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);
}
/*
* 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);
}
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;
}
}
/*
* 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);
}
}
}
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;
}
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;
}
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;
long time_left = 0;
/* rq_xprt should be clear on entry */
WARN_ON_ONCE(rqstp->rq_xprt);
/* Normally we will wait up to 5 seconds for any required
* cache information to be provided.
*/
rqstp->rq_chandle.thread_wait = 5*HZ;
xprt = svc_xprt_dequeue(pool);
if (xprt) {
rqstp->rq_xprt = xprt;
/* As there is a shortage of threads and this request
* had to be queued, don't allow the thread to wait so
* long for cache updates.
*/
rqstp->rq_chandle.thread_wait = 1*HZ;
clear_bit(SP_TASK_PENDING, &pool->sp_flags);
return xprt;
}
/*
* We have to be able to interrupt this wait
* to bring down the daemons ...
*/
set_current_state(TASK_INTERRUPTIBLE);
clear_bit(RQ_BUSY, &rqstp->rq_flags);
smp_mb();
if (likely(rqst_should_sleep(rqstp)))
time_left = schedule_timeout(timeout);
else
__set_current_state(TASK_RUNNING);
try_to_freeze();
spin_lock_bh(&rqstp->rq_lock);
set_bit(RQ_BUSY, &rqstp->rq_flags);
spin_unlock_bh(&rqstp->rq_lock);
xprt = rqstp->rq_xprt;
if (xprt != NULL)
return xprt;
if (!time_left)
atomic_long_inc(&pool->sp_stats.threads_timedout);
if (signalled() || kthread_should_stop())
return ERR_PTR(-EINTR);
return ERR_PTR(-EAGAIN);
}
static void svc_add_new_temp_xprt(struct svc_serv *serv, struct svc_xprt *newxpt)
{
spin_lock_bh(&serv->sv_lock);
set_bit(XPT_TEMP, &newxpt->xpt_flags);
list_add(&newxpt->xpt_list, &serv->sv_tempsocks);
serv->sv_tmpcnt++;
if (serv->sv_temptimer.function == NULL) {
/* setup timer to age temp transports */
setup_timer(&serv->sv_temptimer, svc_age_temp_xprts,
(unsigned long)serv);
mod_timer(&serv->sv_temptimer,
jiffies + svc_conn_age_period * HZ);
}
spin_unlock_bh(&serv->sv_lock);
svc_xprt_received(newxpt);
}
static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
{
struct svc_serv *serv = rqstp->rq_server;
int len = 0;
if (test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
dprintk("svc_recv: found XPT_CLOSE\n");
if (test_and_clear_bit(XPT_KILL_TEMP, &xprt->xpt_flags))
xprt->xpt_ops->xpo_kill_temp_xprt(xprt);
svc_delete_xprt(xprt);
/* Leave XPT_BUSY set on the dead xprt: */
goto out;
}
if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
struct svc_xprt *newxpt;
/*
* We know this module_get will succeed because the
* listener holds a reference too
*/
__module_get(xprt->xpt_class->xcl_owner);
svc_check_conn_limits(xprt->xpt_server);
newxpt = xprt->xpt_ops->xpo_accept(xprt);
if (newxpt)
svc_add_new_temp_xprt(serv, newxpt);
else
module_put(xprt->xpt_class->xcl_owner);
} else if (svc_xprt_reserve_slot(rqstp, xprt)) {
/* XPT_DATA|XPT_DEFERRED case: */
dprintk("svc: server %p, pool %u, transport %p, inuse=%d\n",
rqstp, rqstp->rq_pool->sp_id, xprt,
atomic_read(&xprt->xpt_ref.refcount));
rqstp->rq_deferred = svc_deferred_dequeue(xprt);
if (rqstp->rq_deferred)
len = svc_deferred_recv(rqstp);
else
len = xprt->xpt_ops->xpo_recvfrom(rqstp);
dprintk("svc: got len=%d\n", len);
rqstp->rq_reserved = serv->sv_max_mesg;
atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
}
/* clear XPT_BUSY: */
svc_xprt_received(xprt);
out:
trace_svc_handle_xprt(xprt, len);
return len;
}
/*
* Receive the next request on any transport. This code is carefully
* organised not to touch any cachelines in the shared svc_serv
* structure, only cachelines in the local svc_pool.
*/
int svc_recv(struct svc_rqst *rqstp, long timeout)
{
struct svc_xprt *xprt = NULL;
struct svc_serv *serv = rqstp->rq_server;
int len, err;
dprintk("svc: server %p waiting for data (to = %ld)\n",
rqstp, timeout);
if (rqstp->rq_xprt)
printk(KERN_ERR
"svc_recv: service %p, transport not NULL!\n",
rqstp);
err = svc_alloc_arg(rqstp);
if (err)
goto out;
try_to_freeze();
cond_resched();
err = -EINTR;
if (signalled() || kthread_should_stop())
goto out;
xprt = svc_get_next_xprt(rqstp, timeout);
if (IS_ERR(xprt)) {
err = PTR_ERR(xprt);
goto out;
}
len = svc_handle_xprt(rqstp, xprt);
/* No data, incomplete (TCP) read, or accept() */
err = -EAGAIN;
if (len <= 0)
goto out_release;
clear_bit(XPT_OLD, &xprt->xpt_flags);
if (xprt->xpt_ops->xpo_secure_port(rqstp))
set_bit(RQ_SECURE, &rqstp->rq_flags);
else
clear_bit(RQ_SECURE, &rqstp->rq_flags);
rqstp->rq_chandle.defer = svc_defer;
rqstp->rq_xid = svc_getu32(&rqstp->rq_arg.head[0]);
if (serv->sv_stats)
serv->sv_stats->netcnt++;
trace_svc_recv(rqstp, len);
return len;
out_release:
rqstp->rq_res.len = 0;
svc_xprt_release(rqstp);
out:
trace_svc_recv(rqstp, err);
return err;
}
EXPORT_SYMBOL_GPL(svc_recv);
/*
* Drop request
*/
void svc_drop(struct svc_rqst *rqstp)
{
trace_svc_drop(rqstp);
dprintk("svc: xprt %p dropped request\n", rqstp->rq_xprt);
svc_xprt_release(rqstp);
}
EXPORT_SYMBOL_GPL(svc_drop);
/*
* Return reply to client.
*/
int svc_send(struct svc_rqst *rqstp)
{
struct svc_xprt *xprt;
int len = -EFAULT;
struct xdr_buf *xb;
xprt = rqstp->rq_xprt;
if (!xprt)
goto out;
/* release the receive skb before sending the reply */
rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
/* calculate over-all length */
xb = &rqstp->rq_res;
xb->len = xb->head[0].iov_len +
xb->page_len +
xb->tail[0].iov_len;
/* Grab mutex to serialize outgoing data. */
mutex_lock(&xprt->xpt_mutex);
if (test_bit(XPT_DEAD, &xprt->xpt_flags)
|| test_bit(XPT_CLOSE, &xprt->xpt_flags))
len = -ENOTCONN;
else
len = xprt->xpt_ops->xpo_sendto(rqstp);
mutex_unlock(&xprt->xpt_mutex);
rpc_wake_up(&xprt->xpt_bc_pending);
svc_xprt_release(rqstp);
if (len == -ECONNREFUSED || len == -ENOTCONN || len == -EAGAIN)
len = 0;
out:
trace_svc_send(rqstp, len);
return len;
}
/*
* Timer function to close old temporary transports, using
* a mark-and-sweep algorithm.
*/
static void svc_age_temp_xprts(unsigned long closure)
{
struct svc_serv *serv = (struct svc_serv *)closure;
struct svc_xprt *xprt;
struct list_head *le, *next;
dprintk("svc_age_temp_xprts\n");
if (!spin_trylock_bh(&serv->sv_lock)) {
/* busy, try again 1 sec later */
dprintk("svc_age_temp_xprts: busy\n");
mod_timer(&serv->sv_temptimer, jiffies + HZ);
return;
}
list_for_each_safe(le, next, &serv->sv_tempsocks) {
xprt = list_entry(le, struct svc_xprt, xpt_list);
/* First time through, just mark it OLD. Second time
* through, close it. */
if (!test_and_set_bit(XPT_OLD, &xprt->xpt_flags))
continue;
if (atomic_read(&xprt->xpt_ref.refcount) > 1 ||
test_bit(XPT_BUSY, &xprt->xpt_flags))
continue;
list_del_init(le);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
dprintk("queuing xprt %p for closing\n", xprt);
/* a thread will dequeue and close it soon */
svc_xprt_enqueue(xprt);
}
spin_unlock_bh(&serv->sv_lock);
mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);
}
/* Close temporary transports whose xpt_local matches server_addr immediately
* instead of waiting for them to be picked up by the timer.
*