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Use 'struct callout' instead of 'struct callout_handle' to avoid

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exhausting the kernel timeout table. Perform the usual gymnastics to
avoid race conditions between node shutdown and timeouts occurring.

Also fix a bug in handling ack delays < PPTP_MIN_ACK_DELAY. Before,
we were ack'ing immediately. Instead, just impose a minimum ack delay
time, like the name of the macro implies.

MFC after:	1 week
This commit is contained in:
Archie Cobbs 2002-04-14 17:37:35 +00:00
parent 46e12b42fe
commit 4a48abb26a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=94667
1 changed files with 81 additions and 25 deletions
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106
sys/netgraph/ng_pptpgre.c
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@ -118,7 +118,7 @@ typedef u_int64_t pptptime_t;
/* Acknowledgment timeout parameters and functions */
#define PPTP_XMIT_WIN 16 /* max xmit window */
#define PPTP_MIN_RTT (PPTP_TIME_SCALE / 10) /* 100 milliseconds */
#define PPTP_MIN_TIMEOUT (PPTP_TIME_SCALE / 500) /* 2 milliseconds */
#define PPTP_MIN_TIMEOUT (PPTP_TIME_SCALE / 83) /* 12 milliseconds */
#define PPTP_MAX_TIMEOUT (10 * PPTP_TIME_SCALE) /* 10 seconds */
/* When we recieve a packet, we wait to see if there's an outgoing packet
@ -142,8 +142,8 @@ struct ng_pptpgre_ackp {
int32_t rtt; /* round trip time estimate */
int32_t dev; /* deviation estimate */
u_int16_t xmitWin; /* size of xmit window */
struct callout_handle sackTimer; /* send ack timer */
struct callout_handle rackTimer; /* recv ack timer */
struct callout sackTimer; /* send ack timer */
struct callout rackTimer; /* recv ack timer */
node_p *sackTimerPtr; /* send ack timer pointer */
node_p *rackTimerPtr; /* recv ack timer pointer */
u_int32_t winAck; /* seq when xmitWin will grow */
@ -164,6 +164,7 @@ struct ng_pptpgre_private {
u_int32_t xmitSeq; /* last seq # we sent */
u_int32_t recvAck; /* last seq # peer ack'd */
u_int32_t xmitAck; /* last seq # we ack'd */
u_int timers; /* number of pending timers */
struct timeval startTime; /* time node was created */
struct ng_pptpgre_stats stats; /* node statistics */
};
@ -181,7 +182,9 @@ static ng_disconnect_t ng_pptpgre_disconnect;
static int ng_pptpgre_xmit(node_p node, item_p item);
static int ng_pptpgre_recv(node_p node, item_p item);
static void ng_pptpgre_start_send_ack_timer(node_p node, int ackTimeout);
static void ng_pptpgre_stop_send_ack_timer(node_p node);
static void ng_pptpgre_start_recv_ack_timer(node_p node);
static void ng_pptpgre_stop_recv_ack_timer(node_p node);
static void ng_pptpgre_recv_ack_timeout(void *arg);
static void ng_pptpgre_send_ack_timeout(void *arg);
static void ng_pptpgre_reset(node_p node);
@ -282,8 +285,8 @@ ng_pptpgre_constructor(node_p node)
NG_NODE_SET_PRIVATE(node, priv);
/* Initialize state */
callout_handle_init(&priv->ackp.sackTimer);
callout_handle_init(&priv->ackp.rackTimer);
callout_init(&priv->ackp.sackTimer, 0);
callout_init(&priv->ackp.rackTimer, 0);
/* Done */
return (0);
@ -413,10 +416,14 @@ ng_pptpgre_shutdown(node_p node)
/* Reset node */
ng_pptpgre_reset(node);
/* Take down netgraph node */
bzero(priv, sizeof(*priv));
FREE(priv, M_NETGRAPH);
NG_NODE_SET_PRIVATE(node, NULL);
/* If no timers remain, free private info as well */
if (priv->timers == 0) {
bzero(priv, sizeof(*priv));
FREE(priv, M_NETGRAPH);
NG_NODE_SET_PRIVATE(node, NULL);
}
/* Decrement ref count */
NG_NODE_UNREF(node);
return (0);
}
@ -509,7 +516,7 @@ ng_pptpgre_xmit(node_p node, item_p item)
gre->hasAck = 1;
gre->data[gre->hasSeq] = htonl(priv->recvSeq);
priv->xmitAck = priv->recvSeq;
a->sackTimerPtr = NULL; /* "stop" timer */
ng_pptpgre_stop_send_ack_timer(node);
}
/* Prepend GRE header to outgoing frame */
@ -672,7 +679,7 @@ ng_pptpgre_recv(node_p node, item_p item)
}
/* Stop/(re)start receive ACK timer as necessary */
a->rackTimerPtr = NULL;
ng_pptpgre_stop_recv_ack_timer(node);
if (priv->recvAck != priv->xmitSeq)
ng_pptpgre_start_recv_ack_timer(node);
}
@ -701,10 +708,11 @@ ng_pptpgre_recv(node_p node, item_p item)
maxWait = (a->rtt >> 2);
/* If delayed ACK is disabled, send it now */
if (!priv->conf.enableDelayedAck
|| maxWait < PPTP_MIN_ACK_DELAY)
if (!priv->conf.enableDelayedAck) /* ack now */
ng_pptpgre_xmit(node, NULL);
else { /* send the ack later */
else { /* ack later */
if (maxWait < PPTP_MIN_ACK_DELAY)
maxWait = PPTP_MIN_ACK_DELAY;
if (maxWait > PPTP_MAX_ACK_DELAY)
maxWait = PPTP_MAX_ACK_DELAY;
ng_pptpgre_start_send_ack_timer(node, maxWait);
@ -760,13 +768,31 @@ ng_pptpgre_start_recv_ack_timer(node_p node)
priv->stats.memoryFailures++;
return; /* XXX potential hang here */
}
*a->rackTimerPtr = node; /* insures the correct timeout event */
*a->rackTimerPtr = node; /* ensures the correct timeout event */
NG_NODE_REF(node);
priv->timers++;
/* Be conservative: timeout() can return up to 1 tick early */
/* Be conservative: timeout can happen up to 1 tick early */
ticks = (((remain * hz) + PPTP_TIME_SCALE - 1) / PPTP_TIME_SCALE) + 1;
a->rackTimer = timeout(ng_pptpgre_recv_ack_timeout,
a->rackTimerPtr, ticks);
callout_reset(&a->rackTimer, ticks,
ng_pptpgre_recv_ack_timeout, a->rackTimerPtr);
}
/*
* Stop receive ack timer.
*/
static void
ng_pptpgre_stop_recv_ack_timer(node_p node)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct ng_pptpgre_ackp *const a = &priv->ackp;
if (callout_stop(&a->rackTimer)) {
FREE(a->rackTimerPtr, M_NETGRAPH);
priv->timers--;
NG_NODE_UNREF(node);
}
a->rackTimerPtr = NULL;
}
/*
@ -785,7 +811,13 @@ ng_pptpgre_recv_ack_timeout(void *arg)
/* This complicated stuff is needed to avoid race conditions */
FREE(arg, M_NETGRAPH);
KASSERT(node->nd_refs > 0, ("%s: no nd_refs", __func__));
KASSERT(priv != NULL, ("%s: priv=NULL", __func__));
priv->timers--;
if (NG_NODE_NOT_VALID(node)) { /* shutdown race condition */
if (priv->timers == 0) {
FREE(priv, M_NETGRAPH);
NG_NODE_SET_PRIVATE(node, NULL);
}
NG_NODE_UNREF(node);
splx(s);
return;
@ -839,13 +871,31 @@ ng_pptpgre_start_send_ack_timer(node_p node, int ackTimeout)
priv->stats.memoryFailures++;
return; /* XXX potential hang here */
}
*a->sackTimerPtr = node;
*a->sackTimerPtr = node; /* ensures the correct timeout event */
NG_NODE_REF(node);
priv->timers++;
/* Be conservative: timeout() can return up to 1 tick early */
/* Be conservative: timeout can happen up to 1 tick early */
ticks = (((ackTimeout * hz) + PPTP_TIME_SCALE - 1) / PPTP_TIME_SCALE);
a->sackTimer = timeout(ng_pptpgre_send_ack_timeout,
a->sackTimerPtr, ticks);
callout_reset(&a->sackTimer, ticks,
ng_pptpgre_send_ack_timeout, a->sackTimerPtr);
}
/*
* Stop send ack timer.
*/
static void
ng_pptpgre_stop_send_ack_timer(node_p node)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct ng_pptpgre_ackp *const a = &priv->ackp;
if (callout_stop(&a->sackTimer)) {
FREE(a->sackTimerPtr, M_NETGRAPH);
priv->timers--;
NG_NODE_UNREF(node);
}
a->sackTimerPtr = NULL;
}
/*
@ -865,7 +915,13 @@ ng_pptpgre_send_ack_timeout(void *arg)
/* This complicated stuff is needed to avoid race conditions */
FREE(arg, M_NETGRAPH);
KASSERT(node->nd_refs > 0, ("%s: no nd_refs", __func__));
KASSERT(priv != NULL, ("%s: priv=NULL", __func__));
priv->timers--;
if (NG_NODE_NOT_VALID(node)) { /* shutdown race condition */
if (priv->timers == 0) {
FREE(priv, M_NETGRAPH);
NG_NODE_SET_PRIVATE(node, NULL);
}
NG_NODE_UNREF(node);
splx(s);
return;
@ -921,9 +977,9 @@ ng_pptpgre_reset(node_p node)
/* Reset stats */
bzero(&priv->stats, sizeof(priv->stats));
/* "Stop" timers */
a->sackTimerPtr = NULL;
a->rackTimerPtr = NULL;
/* Stop timers */
ng_pptpgre_stop_send_ack_timer(node);
ng_pptpgre_stop_recv_ack_timer(node);
}
/*