cregit-Linux how code gets into the kernel

Release 4.8 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; }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker99100.00%1100.00%
Total99100.00%1100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker39100.00%1100.00%
Total39100.00%1100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker9994.29%150.00%
pavel emelianovpavel emelianov65.71%150.00%
Total105100.00%2100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker6866.67%240.00%
j. bruce fieldsj. bruce fields2726.47%240.00%
pavel emelianovpavel emelianov76.86%120.00%
Total102100.00%5100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker20100.00%1100.00%
Total20100.00%1100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker11177.62%866.67%
rahul iyerrahul iyer106.99%18.33%
j. bruce fieldsj. bruce fields85.59%18.33%
pavel emelianovpavel emelianov85.59%18.33%
stanislav kinsburskystanislav 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); }

Contributors

PersonTokensPropCommitsCommitProp
chuck leverchuck lever13472.04%342.86%
tom tuckertom tucker4021.51%114.29%
pavel emelianovpavel emelianov73.76%114.29%
al viroal viro31.61%114.29%
eric dumazeteric 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); }

Contributors

PersonTokensPropCommitsCommitProp
j. bruce fieldsj. bruce fields4563.38%120.00%
jeff laytonjeff layton1825.35%240.00%
weston andros adamsonweston andros adamson57.04%120.00%
trond myklebusttrond myklebust34.23%120.00%
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); }

Contributors

PersonTokensPropCommitsCommitProp
j. bruce fieldsj. bruce fields59100.00%1100.00%
Total59100.00%1100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker9860.49%330.00%
chuck leverchuck lever3622.22%220.00%
neil brownneil brown127.41%110.00%
j. bruce fieldsj. bruce fields95.56%220.00%
pavel emelianovpavel emelianov74.32%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; }

Contributors

PersonTokensPropCommitsCommitProp
j. bruce fieldsj. bruce fields10090.91%125.00%
tom tuckertom tucker98.18%250.00%
chuck leverchuck lever10.91%125.00%
Total110100.00%4100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker5278.79%150.00%
mi jinlongmi jinlong1421.21%150.00%
Total66100.00%2100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker31100.00%1100.00%
Total31100.00%1100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
trond myklebusttrond myklebust43100.00%1100.00%
Total43100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
trond myklebusttrond myklebust63100.00%1100.00%
Total63100.00%1100.00%


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); } }

Contributors

PersonTokensPropCommitsCommitProp
trond myklebusttrond myklebust47100.00%1100.00%
Total47100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
j. bruce fieldsj. bruce fields6676.74%133.33%
trond myklebusttrond myklebust2023.26%266.67%
Total86100.00%3100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
jeff laytonjeff layton12945.10%330.00%
tom tuckertom tucker9633.57%110.00%
trond myklebusttrond myklebust3712.94%330.00%
greg banksgreg banks196.64%110.00%
j. bruce fieldsj. bruce fields51.75%220.00%
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); }

Contributors

PersonTokensPropCommitsCommitProp
trond myklebusttrond myklebust2779.41%150.00%
jeff laytonjeff layton720.59%150.00%
Total34100.00%2100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker6957.50%133.33%
jeff laytonjeff layton5142.50%266.67%
Total120100.00%3100.00%

/** * 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); } }

Contributors

PersonTokensPropCommitsCommitProp
tom tuckertom tucker72100.00%1100.00%
Total72100.00%1100.00%

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 tuckertom tucker12796.21%266.67%
trond myklebusttrond 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 tuckertom tucker5350.00%114.29%
jeff laytonjeff layton4845.28%457.14%
andriy skulyshandriy skulysh32.83%114.29%
trond myklebusttrond 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 tuckertom 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 tuckertom tucker11780.69%133.33%
jeff laytonjeff layton2416.55%133.33%
joe perchesjoe 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 tuckertom tucker19674.24%111.11%
jeff laytonjeff layton3312.50%333.33%
j. bruce fieldsj. bruce fields197.20%222.22%
weston andros adamsonweston andros adamson145.30%111.11%
rashika kheriarashika kheria10.38%111.11%
greg banksgreg banks10.38%111.11%
Total264100.00%9100.00%


static bool rqst_should_sleep(struct svc_rqst *rqstp)