cregit-Linux how code gets into the kernel

Release 4.14 net/rds/send.c

Directory: net/rds
 * Copyright (c) 2006 Oracle.  All rights reserved.
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * BSD license below:
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/gfp.h>
#include <net/sock.h>
#include <linux/in.h>
#include <linux/list.h>
#include <linux/ratelimit.h>
#include <linux/export.h>
#include <linux/sizes.h>

#include "rds.h"

/* When transmitting messages in rds_send_xmit, we need to emerge from
 * time to time and briefly release the CPU. Otherwise the softlock watchdog
 * will kick our shin.
 * Also, it seems fairer to not let one busy connection stall all the
 * others.
 * send_batch_count is the number of times we'll loop in send_xmit. Setting
 * it to 0 will restore the old behavior (where we looped until we had
 * drained the queue).

static int send_batch_count = SZ_1K;
module_param(send_batch_count, int, 0444);
MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");

static void rds_send_remove_from_sock(struct list_head *messages, int status);

 * Reset the send state.  Callers must ensure that this doesn't race with
 * rds_send_xmit().

void rds_send_path_reset(struct rds_conn_path *cp) { struct rds_message *rm, *tmp; unsigned long flags; if (cp->cp_xmit_rm) { rm = cp->cp_xmit_rm; cp->cp_xmit_rm = NULL; /* Tell the user the RDMA op is no longer mapped by the * transport. This isn't entirely true (it's flushed out * independently) but as the connection is down, there's * no ongoing RDMA to/from that memory */ rds_message_unmapped(rm); rds_message_put(rm); } cp->cp_xmit_sg = 0; cp->cp_xmit_hdr_off = 0; cp->cp_xmit_data_off = 0; cp->cp_xmit_atomic_sent = 0; cp->cp_xmit_rdma_sent = 0; cp->cp_xmit_data_sent = 0; cp->cp_conn->c_map_queued = 0; cp->cp_unacked_packets = rds_sysctl_max_unacked_packets; cp->cp_unacked_bytes = rds_sysctl_max_unacked_bytes; /* Mark messages as retransmissions, and move them to the send q */ spin_lock_irqsave(&cp->cp_lock, flags); list_for_each_entry_safe(rm, tmp, &cp->cp_retrans, m_conn_item) { set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags); set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags); } list_splice_init(&cp->cp_retrans, &cp->cp_send_queue); spin_unlock_irqrestore(&cp->cp_lock, flags); }


Andy Grover12571.43%360.00%
Sowmini Varadhan3721.14%120.00%
Chris Mason137.43%120.00%

static int acquire_in_xmit(struct rds_conn_path *cp) { return test_and_set_bit(RDS_IN_XMIT, &cp->cp_flags) == 0; }


Zach Brown2083.33%150.00%
Sowmini Varadhan416.67%150.00%

static void release_in_xmit(struct rds_conn_path *cp) { clear_bit(RDS_IN_XMIT, &cp->cp_flags); smp_mb__after_atomic(); /* * We don't use wait_on_bit()/wake_up_bit() because our waking is in a * hot path and finding waiters is very rare. We don't want to walk * the system-wide hashed waitqueue buckets in the fast path only to * almost never find waiters. */ if (waitqueue_active(&cp->cp_waitq)) wake_up_all(&cp->cp_waitq); }


Zach Brown3479.07%133.33%
Sowmini Varadhan818.60%133.33%
Peter Zijlstra12.33%133.33%

/* * We're making the conscious trade-off here to only send one message * down the connection at a time. * Pro: * - tx queueing is a simple fifo list * - reassembly is optional and easily done by transports per conn * - no per flow rx lookup at all, straight to the socket * - less per-frag memory and wire overhead * Con: * - queued acks can be delayed behind large messages * Depends: * - small message latency is higher behind queued large messages * - large message latency isn't starved by intervening small sends */
int rds_send_xmit(struct rds_conn_path *cp) { struct rds_connection *conn = cp->cp_conn; struct rds_message *rm; unsigned long flags; unsigned int tmp; struct scatterlist *sg; int ret = 0; LIST_HEAD(to_be_dropped); int batch_count; unsigned long send_gen = 0; restart: batch_count = 0; /* * sendmsg calls here after having queued its message on the send * queue. We only have one task feeding the connection at a time. If * another thread is already feeding the queue then we back off. This * avoids blocking the caller and trading per-connection data between * caches per message. */ if (!acquire_in_xmit(cp)) { rds_stats_inc(s_send_lock_contention); ret = -ENOMEM; goto out; } /* * we record the send generation after doing the xmit acquire. * if someone else manages to jump in and do some work, we'll use * this to avoid a goto restart farther down. * * The acquire_in_xmit() check above ensures that only one * caller can increment c_send_gen at any time. */ send_gen = READ_ONCE(cp->cp_send_gen) + 1; WRITE_ONCE(cp->cp_send_gen, send_gen); /* * rds_conn_shutdown() sets the conn state and then tests RDS_IN_XMIT, * we do the opposite to avoid races. */ if (!rds_conn_path_up(cp)) { release_in_xmit(cp); ret = 0; goto out; } if (conn->c_trans->xmit_path_prepare) conn->c_trans->xmit_path_prepare(cp); /* * spin trying to push headers and data down the connection until * the connection doesn't make forward progress. */ while (1) { rm = cp->cp_xmit_rm; /* * If between sending messages, we can send a pending congestion * map update. */ if (!rm && test_and_clear_bit(0, &conn->c_map_queued)) { rm = rds_cong_update_alloc(conn); if (IS_ERR(rm)) { ret = PTR_ERR(rm); break; } rm->data.op_active = 1; rm->m_inc.i_conn_path = cp; rm->m_inc.i_conn = cp->cp_conn; cp->cp_xmit_rm = rm; } /* * If not already working on one, grab the next message. * * cp_xmit_rm holds a ref while we're sending this message down * the connction. We can use this ref while holding the * send_sem.. rds_send_reset() is serialized with it. */ if (!rm) { unsigned int len; batch_count++; /* we want to process as big a batch as we can, but * we also want to avoid softlockups. If we've been * through a lot of messages, lets back off and see * if anyone else jumps in */ if (batch_count >= send_batch_count) goto over_batch; spin_lock_irqsave(&cp->cp_lock, flags); if (!list_empty(&cp->cp_send_queue)) { rm = list_entry(cp->, struct rds_message, m_conn_item); rds_message_addref(rm); /* * Move the message from the send queue to the retransmit * list right away. */ list_move_tail(&rm->m_conn_item, &cp->cp_retrans); } spin_unlock_irqrestore(&cp->cp_lock, flags); if (!rm) break; /* Unfortunately, the way Infiniband deals with * RDMA to a bad MR key is by moving the entire * queue pair to error state. We cold possibly * recover from that, but right now we drop the * connection. * Therefore, we never retransmit messages with RDMA ops. */ if (test_bit(RDS_MSG_FLUSH, &rm->m_flags) || (rm->rdma.op_active && test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))) { spin_lock_irqsave(&cp->cp_lock, flags); if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) list_move(&rm->m_conn_item, &to_be_dropped); spin_unlock_irqrestore(&cp->cp_lock, flags); continue; } /* Require an ACK every once in a while */ len = ntohl(rm->m_inc.i_hdr.h_len); if (cp->cp_unacked_packets == 0 || cp->cp_unacked_bytes < len) { set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags); cp->cp_unacked_packets = rds_sysctl_max_unacked_packets; cp->cp_unacked_bytes = rds_sysctl_max_unacked_bytes; rds_stats_inc(s_send_ack_required); } else { cp->cp_unacked_bytes -= len; cp->cp_unacked_packets--; } cp->cp_xmit_rm = rm; } /* The transport either sends the whole rdma or none of it */ if (rm->rdma.op_active && !cp->cp_xmit_rdma_sent) { rm->m_final_op = &rm->rdma; /* The transport owns the mapped memory for now. * You can't unmap it while it's on the send queue */ set_bit(RDS_MSG_MAPPED, &rm->m_flags); ret = conn->c_trans->xmit_rdma(conn, &rm->rdma); if (ret) { clear_bit(RDS_MSG_MAPPED, &rm->m_flags); wake_up_interruptible(&rm->m_flush_wait); break; } cp->cp_xmit_rdma_sent = 1; } if (rm->atomic.op_active && !cp->cp_xmit_atomic_sent) { rm->m_final_op = &rm->atomic; /* The transport owns the mapped memory for now. * You can't unmap it while it's on the send queue */ set_bit(RDS_MSG_MAPPED, &rm->m_flags); ret = conn->c_trans->xmit_atomic(conn, &rm->atomic); if (ret) { clear_bit(RDS_MSG_MAPPED, &rm->m_flags); wake_up_interruptible(&rm->m_flush_wait); break; } cp->cp_xmit_atomic_sent = 1; } /* * A number of cases require an RDS header to be sent * even if there is no data. * We permit 0-byte sends; rds-ping depends on this. * However, if there are exclusively attached silent ops, * we skip the hdr/data send, to enable silent operation. */ if (rm->data.op_nents == 0) { int ops_present; int all_ops_are_silent = 1; ops_present = (rm->atomic.op_active || rm->rdma.op_active); if (rm->atomic.op_active && !rm->atomic.op_silent) all_ops_are_silent = 0; if (rm->rdma.op_active && !rm->rdma.op_silent) all_ops_are_silent = 0; if (ops_present && all_ops_are_silent && !rm->m_rdma_cookie) rm->data.op_active = 0; } if (rm->data.op_active && !cp->cp_xmit_data_sent) { rm->m_final_op = &rm->data; ret = conn->c_trans->xmit(conn, rm, cp->cp_xmit_hdr_off, cp->cp_xmit_sg, cp->cp_xmit_data_off); if (ret <= 0) break; if (cp->cp_xmit_hdr_off < sizeof(struct rds_header)) { tmp = min_t(int, ret, sizeof(struct rds_header) - cp->cp_xmit_hdr_off); cp->cp_xmit_hdr_off += tmp; ret -= tmp; } sg = &rm->data.op_sg[cp->cp_xmit_sg]; while (ret) { tmp = min_t(int, ret, sg->length - cp->cp_xmit_data_off); cp->cp_xmit_data_off += tmp; ret -= tmp; if (cp->cp_xmit_data_off == sg->length) { cp->cp_xmit_data_off = 0; sg++; cp->cp_xmit_sg++; BUG_ON(ret != 0 && cp->cp_xmit_sg == rm->data.op_nents); } } if (cp->cp_xmit_hdr_off == sizeof(struct rds_header) && (cp->cp_xmit_sg == rm->data.op_nents)) cp->cp_xmit_data_sent = 1; } /* * A rm will only take multiple times through this loop * if there is a data op. Thus, if the data is sent (or there was * none), then we're done with the rm. */ if (!rm->data.op_active || cp->cp_xmit_data_sent) { cp->cp_xmit_rm = NULL; cp->cp_xmit_sg = 0; cp->cp_xmit_hdr_off = 0; cp->cp_xmit_data_off = 0; cp->cp_xmit_rdma_sent = 0; cp->cp_xmit_atomic_sent = 0; cp->cp_xmit_data_sent = 0; rds_message_put(rm); } } over_batch: if (conn->c_trans->xmit_path_complete) conn->c_trans->xmit_path_complete(cp); release_in_xmit(cp); /* Nuke any messages we decided not to retransmit. */ if (!list_empty(&to_be_dropped)) { /* irqs on here, so we can put(), unlike above */ list_for_each_entry(rm, &to_be_dropped, m_conn_item) rds_message_put(rm); rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED); } /* * Other senders can queue a message after we last test the send queue * but before we clear RDS_IN_XMIT. In that case they'd back off and * not try and send their newly queued message. We need to check the * send queue after having cleared RDS_IN_XMIT so that their message * doesn't get stuck on the send queue. * * If the transport cannot continue (i.e ret != 0), then it must * call us when more room is available, such as from the tx * completion handler. * * We have an extra generation check here so that if someone manages * to jump in after our release_in_xmit, we'll see that they have done * some work and we will skip our goto */ if (ret == 0) { bool raced; smp_mb(); raced = send_gen != READ_ONCE(cp->cp_send_gen); if ((test_bit(0, &conn->c_map_queued) || !list_empty(&cp->cp_send_queue)) && !raced) { if (batch_count < send_batch_count) goto restart; queue_delayed_work(rds_wq, &cp->cp_send_w, 1); } else if (raced) { rds_stats_inc(s_send_lock_queue_raced); } } out: return ret; }


Andy Grover82069.61%1456.00%
Sowmini Varadhan20117.06%312.00%
Santosh Shilimkar837.05%312.00%
Håkon Bugge413.48%312.00%
Zach Brown302.55%14.00%
Chris Mason30.25%14.00%

static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm) { u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len); assert_spin_locked(&rs->rs_lock); BUG_ON(rs->rs_snd_bytes < len); rs->rs_snd_bytes -= len; if (rs->rs_snd_bytes == 0) rds_stats_inc(s_send_queue_empty); }


Andy Grover66100.00%1100.00%

static inline int rds_send_is_acked(struct rds_message *rm, u64 ack, is_acked_func is_acked) { if (is_acked) return is_acked(rm, ack); return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack; }


Andy Grover44100.00%1100.00%

/* * This is pretty similar to what happens below in the ACK * handling code - except that we call here as soon as we get * the IB send completion on the RDMA op and the accompanying * message. */
void rds_rdma_send_complete(struct rds_message *rm, int status) { struct rds_sock *rs = NULL; struct rm_rdma_op *ro; struct rds_notifier *notifier; unsigned long flags; unsigned int notify = 0; spin_lock_irqsave(&rm->m_rs_lock, flags); notify = rm->rdma.op_notify | rm->data.op_notify; ro = &rm->rdma; if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) && ro->op_active && notify && ro->op_notifier) { notifier = ro->op_notifier; rs = rm->m_rs; sock_hold(rds_rs_to_sk(rs)); notifier->n_status = status; spin_lock(&rs->rs_lock); list_add_tail(&notifier->n_list, &rs->rs_notify_queue); spin_unlock(&rs->rs_lock); ro->op_notifier = NULL; } spin_unlock_irqrestore(&rm->m_rs_lock, flags); if (rs) { rds_wake_sk_sleep(rs); sock_put(rds_rs_to_sk(rs)); } }


Andy Grover16488.65%583.33%
Santosh Shilimkar2111.35%116.67%

EXPORT_SYMBOL_GPL(rds_rdma_send_complete); /* * Just like above, except looks at atomic op */
void rds_atomic_send_complete(struct rds_message *rm, int status) { struct rds_sock *rs = NULL; struct rm_atomic_op *ao; struct rds_notifier *notifier; unsigned long flags; spin_lock_irqsave(&rm->m_rs_lock, flags); ao = &rm->atomic; if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) && ao->op_active && ao->op_notify && ao->op_notifier) { notifier = ao->op_notifier; rs = rm->m_rs; sock_hold(rds_rs_to_sk(rs)); notifier->n_status = status; spin_lock(&rs->rs_lock); list_add_tail(&notifier->n_list, &rs->rs_notify_queue); spin_unlock(&rs->rs_lock); ao->op_notifier = NULL; } spin_unlock_irqrestore(&rm->m_rs_lock, flags); if (rs) { rds_wake_sk_sleep(rs); sock_put(rds_rs_to_sk(rs)); } }


Andy Grover167100.00%2100.00%

EXPORT_SYMBOL_GPL(rds_atomic_send_complete); /* * This is the same as rds_rdma_send_complete except we * don't do any locking - we have all the ingredients (message, * socket, socket lock) and can just move the notifier. */
static inline void __rds_send_complete(struct rds_sock *rs, struct rds_message *rm, int status) { struct rm_rdma_op *ro; struct rm_atomic_op *ao; ro = &rm->rdma; if (ro->op_active && ro->op_notify && ro->op_notifier) { ro->op_notifier->n_status = status; list_add_tail(&ro->op_notifier->n_list, &rs->rs_notify_queue); ro->op_notifier = NULL; } ao = &rm->atomic; if (ao->op_active && ao->op_notify && ao->op_notifier) { ao->op_notifier->n_status = status; list_add_tail(&ao->op_notifier->n_list, &rs->rs_notify_queue); ao->op_notifier = NULL; } /* No need to wake the app - caller does this */ }


Andy Grover135100.00%5100.00%

/* * This removes messages from the socket's list if they're on it. The list * argument must be private to the caller, we must be able to modify it * without locks. The messages must have a reference held for their * position on the list. This function will drop that reference after * removing the messages from the 'messages' list regardless of if it found * the messages on the socket list or not. */
static void rds_send_remove_from_sock(struct list_head *messages, int status) { unsigned long flags; struct rds_sock *rs = NULL; struct rds_message *rm; while (!list_empty(messages)) { int was_on_sock = 0; rm = list_entry(messages->next, struct rds_message, m_conn_item); list_del_init(&rm->m_conn_item); /* * If we see this flag cleared then we're *sure* that someone * else beat us to removing it from the sock. If we race * with their flag update we'll get the lock and then really * see that the flag has been cleared. * * The message spinlock makes sure nobody clears rm->m_rs * while we're messing with it. It does not prevent the * message from being removed from the socket, though. */ spin_lock_irqsave(&rm->m_rs_lock, flags); if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) goto unlock_and_drop; if (rs != rm->m_rs) { if (rs) { rds_wake_sk_sleep(rs); sock_put(rds_rs_to_sk(rs)); } rs = rm->m_rs; if (rs) sock_hold(rds_rs_to_sk(rs)); } if (!rs) goto unlock_and_drop; spin_lock(&rs->rs_lock); if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) { struct rm_rdma_op *ro = &rm->rdma; struct rds_notifier *notifier; list_del_init(&rm->m_sock_item); rds_send_sndbuf_remove(rs, rm); if (ro->op_active && ro->op_notifier && (ro->op_notify || (ro->op_recverr && status))) { notifier = ro->op_notifier; list_add_tail(&notifier->n_list, &rs->rs_notify_queue); if (!notifier->n_status) notifier->n_status = status; rm->rdma.op_notifier = NULL; } was_on_sock = 1; rm->m_rs = NULL; } spin_unlock(&rs->rs_lock); unlock_and_drop: spin_unlock_irqrestore(&rm->m_rs_lock, flags); rds_message_put(rm); if (was_on_sock) rds_message_put(rm); } if (rs) { rds_wake_sk_sleep(rs); sock_put(rds_rs_to_sk(rs)); } }


Andy Grover30191.21%666.67%
Tina Yang164.85%111.11%
Herton Ronaldo Krzesinski123.64%111.11%
Stephen Hemminger10.30%111.11%

/* * Transports call here when they've determined that the receiver queued * messages up to, and including, the given sequence number. Messages are * moved to the retrans queue when rds_send_xmit picks them off the send * queue. This means that in the TCP case, the message may not have been * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked * checks the RDS_MSG_HAS_ACK_SEQ bit. */
void rds_send_path_drop_acked(struct rds_conn_path *cp, u64 ack, is_acked_func is_acked) { struct rds_message *rm, *tmp; unsigned long flags; LIST_HEAD(list); spin_lock_irqsave(&cp->cp_lock, flags); list_for_each_entry_safe(rm, tmp, &cp->cp_retrans, m_conn_item) { if (!rds_send_is_acked(rm, ack, is_acked)) break; list_move(&rm->m_conn_item, &list); clear_bit(RDS_MSG_ON_CONN, &rm->m_flags); } /* order flag updates with spin locks */ if (!list_empty(&list)) smp_mb__after_atomic(); spin_unlock_irqrestore(&cp->cp_lock, flags); /* now remove the messages from the sock list as needed */ rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS); }


Andy Grover11292.56%133.33%
Sowmini Varadhan86.61%133.33%
Peter Zijlstra10.83%133.33%

void rds_send_drop_acked(struct rds_connection *conn, u64 ack, is_acked_func is_acked) { WARN_ON(conn->c_trans->t_mp_capable); rds_send_path_drop_acked(&conn->c_path[0], ack, is_acked); }


Sowmini Varadhan40100.00%1100.00%

void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest) { struct rds_message *rm, *tmp; struct rds_connection *conn; struct rds_conn_path *cp; unsigned long flags; LIST_HEAD(list); /* get all the messages we're dropping under the rs lock */ spin_lock_irqsave(&rs->rs_lock, flags); list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) { if (dest && (dest->sin_addr.s_addr != rm->m_daddr || dest->sin_port != rm->m_inc.i_hdr.h_dport)) continue; list_move(&rm->m_sock_item, &list); rds_send_sndbuf_remove(rs, rm); clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags); } /* order flag updates with the rs lock */ smp_mb__after_atomic(); spin_unlock_irqrestore(&rs->rs_lock, flags); if (list_empty(&list)) return; /* Remove the messages from the conn */ list_for_each_entry(rm, &list, m_sock_item) { conn = rm->m_inc.i_conn; if (conn->c_trans->t_mp_capable) cp = rm->m_inc.i_conn_path; else cp = &conn->c_path[0]; spin_lock_irqsave(&cp->cp_lock, flags); /* * Maybe someone else beat us to removing rm from the conn. * If we race with their flag update we'll get the lock and * then really see that the flag has been cleared. */ if (!test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) { spin_unlock_irqrestore(&cp->cp_lock, flags); spin_lock_irqsave(&rm->m_rs_lock, flags); rm->m_rs = NULL; spin_unlock_irqrestore(&rm->m_rs_lock, flags); continue; } list_del_init(&rm->m_conn_item); spin_unlock_irqrestore(&cp->cp_lock, flags); /* * Couldn't grab m_rs_lock in top loop (lock ordering), * but we can now. */ spin_lock_irqsave(&rm->m_rs_lock, flags); spin_lock(&rs->rs_lock); __rds_send_complete(rs, rm, RDS_RDMA_CANCELED); spin_unlock(&rs->rs_lock); rm->m_rs = NULL; spin_unlock_irqrestore(&rm->m_rs_lock, flags); rds_message_put(rm); } rds_wake_sk_sleep(rs); while (!list_empty(&list)) { rm = list_entry(, struct rds_message, m_sock_item); list_del_init(&rm->m_sock_item); rds_message_wait(rm); /* just in case the code above skipped this message * because RDS_MSG_ON_CONN wasn't set, run it again here * taking m_rs_lock is the only thing that keeps us * from racing with ack processing. */ spin_lock_irqsave(&rm->m_rs_lock, flags); spin_lock(&rs->rs_lock); __rds_send_complete(rs, rm, RDS_RDMA_CANCELED); spin_unlock(&rs->rs_lock); rm->m_rs = NULL; spin_unlock_irqrestore(&rm->m_rs_lock, flags); rds_message_put(rm); } }


Andy Grover30771.56%550.00%
Santosh Shilimkar5212.12%110.00%
Sowmini Varadhan388.86%110.00%
Herton Ronaldo Krzesinski266.06%110.00%
Tina Yang51.17%110.00%
Peter Zijlstra10.23%110.00%

/* * we only want this to fire once so we use the callers 'queued'. It's * possible that another thread can race with us and remove the * message from the flow with RDS_CANCEL_SENT_TO. */
static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn, struct rds_conn_path *cp, struct rds_message *rm, __be16 sport, __be16 dport, int *queued) { unsigned long flags; u32 len; if (*queued) goto out; len = be32_to_cpu(rm->m_inc.i_hdr.h_len); /* this is the only place which holds both the socket's rs_lock * and the connection's c_lock */ spin_lock_irqsave(&rs->rs_lock, flags); /* * If there is a little space in sndbuf, we don't queue anything, * and userspace gets -EAGAIN. But poll() indicates there's send * room. This can lead to bad behavior (spinning) if snd_bytes isn't * freed up by incoming acks. So we check the *old* value of * rs_snd_bytes here to allow the last msg to exceed the buffer, * and poll() now knows no more data can be sent. */ if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) { rs->rs_snd_bytes += len; /* let recv side know we are close to send space exhaustion. * This is probably not the optimal way to do it, as this * means we set the flag on *all* messages as soon as our * throughput hits a certain threshold. */ if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2) set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags); list_add_tail(&rm->m_sock_item, &rs->rs_send_queue); set_bit(RDS_MSG_ON_SOCK, &rm->m_flags); rds_message_addref(rm); rm->m_rs = rs; /* The code ordering is a little weird, but we're trying to minimize the time we hold c_lock */ rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0); rm->m_inc.i_conn = conn; rm