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Put r284245 back in place: If at first this fix was seen as a temporary

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workaround for a callout(9) issue, it turns out it is instead the right
way to use callout in mpsafe mode without using callout_drain().

r284245 commit message:

Fix a callout race condition introduced in TCP timers callouts with r281599.
In TCP timer context, it is not enough to check callout_stop() return value
to decide if a callout is still running or not, previous callout_reset()
return values have also to be checked.

Differential Revision:	https://reviews.freebsd.org/D2763
This commit is contained in:
Julien Charbon 2015-08-30 13:44:39 +00:00
parent 42404113e6
commit d6de19ac2f
2 changed files with 45 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
sys/netinet/tcp_timer.c
View File

@ -355,10 +355,12 @@ tcp_timer_2msl(void *xtp)
TCPSTAT_INC(tcps_finwait2_drops);
tp = tcp_close(tp);
} else {
if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp))
callout_reset(&tp->t_timers->tt_2msl,
TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
else
if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
if (!callout_reset(&tp->t_timers->tt_2msl,
TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) {
tp->t_timers->tt_flags &= ~TT_2MSL_RST;
}
} else
tp = tcp_close(tp);
}
@ -438,11 +440,14 @@ tcp_timer_keep(void *xtp)
tp->rcv_nxt, tp->snd_una - 1, 0);
free(t_template, M_TEMP);
}
callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
tcp_timer_keep, tp);
} else
callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
tcp_timer_keep, tp);
if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
tcp_timer_keep, tp)) {
tp->t_timers->tt_flags &= ~TT_KEEP_RST;
}
} else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
tcp_timer_keep, tp)) {
tp->t_timers->tt_flags &= ~TT_KEEP_RST;
}
#ifdef TCPDEBUG
if (inp->inp_socket->so_options & SO_DEBUG)
@ -801,6 +806,7 @@ tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
timeout_t *f_callout;
struct inpcb *inp = tp->t_inpcb;
int cpu = inp_to_cpuid(inp);
uint32_t f_reset;
#ifdef TCP_OFFLOAD
if (tp->t_flags & TF_TOE)
@ -814,38 +820,49 @@ tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
case TT_DELACK:
t_callout = &tp->t_timers->tt_delack;
f_callout = tcp_timer_delack;
f_reset = TT_DELACK_RST;
break;
case TT_REXMT:
t_callout = &tp->t_timers->tt_rexmt;
f_callout = tcp_timer_rexmt;
f_reset = TT_REXMT_RST;
break;
case TT_PERSIST:
t_callout = &tp->t_timers->tt_persist;
f_callout = tcp_timer_persist;
f_reset = TT_PERSIST_RST;
break;
case TT_KEEP:
t_callout = &tp->t_timers->tt_keep;
f_callout = tcp_timer_keep;
f_reset = TT_KEEP_RST;
break;
case TT_2MSL:
t_callout = &tp->t_timers->tt_2msl;
f_callout = tcp_timer_2msl;
f_reset = TT_2MSL_RST;
break;
default:
panic("tp %p bad timer_type %#x", tp, timer_type);
}
if (delta == 0) {
if ((tp->t_timers->tt_flags & timer_type) &&
callout_stop(t_callout)) {
tp->t_timers->tt_flags &= ~timer_type;
callout_stop(t_callout) &&
(tp->t_timers->tt_flags & f_reset)) {
tp->t_timers->tt_flags &= ~(timer_type | f_reset);
}
} else {
if ((tp->t_timers->tt_flags & timer_type) == 0) {
tp->t_timers->tt_flags |= timer_type;
tp->t_timers->tt_flags |= (timer_type | f_reset);
callout_reset_on(t_callout, delta, f_callout, tp, cpu);
} else {
/* Reset already running callout on the same CPU. */
callout_reset(t_callout, delta, f_callout, tp);
if (!callout_reset(t_callout, delta, f_callout, tp)) {
/*
* Callout not cancelled, consider it as not
* properly restarted. */
tp->t_timers->tt_flags &= ~f_reset;
}
}
}
}
@ -882,6 +899,7 @@ tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
{
struct callout *t_callout;
timeout_t *f_callout;
uint32_t f_reset;
tp->t_timers->tt_flags |= TT_STOPPED;
@ -889,30 +907,36 @@ tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
case TT_DELACK:
t_callout = &tp->t_timers->tt_delack;
f_callout = tcp_timer_delack_discard;
f_reset = TT_DELACK_RST;
break;
case TT_REXMT:
t_callout = &tp->t_timers->tt_rexmt;
f_callout = tcp_timer_rexmt_discard;
f_reset = TT_REXMT_RST;
break;
case TT_PERSIST:
t_callout = &tp->t_timers->tt_persist;
f_callout = tcp_timer_persist_discard;
f_reset = TT_PERSIST_RST;
break;
case TT_KEEP:
t_callout = &tp->t_timers->tt_keep;
f_callout = tcp_timer_keep_discard;
f_reset = TT_KEEP_RST;
break;
case TT_2MSL:
t_callout = &tp->t_timers->tt_2msl;
f_callout = tcp_timer_2msl_discard;
f_reset = TT_2MSL_RST;
break;
default:
panic("tp %p bad timer_type %#x", tp, timer_type);
}
if (tp->t_timers->tt_flags & timer_type) {
if (callout_stop(t_callout)) {
tp->t_timers->tt_flags &= ~timer_type;
if (callout_stop(t_callout) &&
(tp->t_timers->tt_flags & f_reset)) {
tp->t_timers->tt_flags &= ~(timer_type | f_reset);
} else {
/*
* Can't stop the callout, defer tcpcb actual deletion

6
sys/netinet/tcp_timer.h
View File

@ -159,6 +159,12 @@ struct tcp_timer {
#define TT_2MSL 0x0010
#define TT_MASK (TT_DELACK|TT_REXMT|TT_PERSIST|TT_KEEP|TT_2MSL)
#define TT_DELACK_RST 0x0100
#define TT_REXMT_RST 0x0200
#define TT_PERSIST_RST 0x0400
#define TT_KEEP_RST 0x0800
#define TT_2MSL_RST 0x1000
#define TT_STOPPED 0x00010000
#define TP_KEEPINIT(tp) ((tp)->t_keepinit ? (tp)->t_keepinit : tcp_keepinit)