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zebra: Prevent possible wedged fpm write #15025

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merged 2 commits into from
Dec 14, 2023
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zebra: Prevent possible wedged fpm write #15025

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3209ca4
zebra: Prevent possible wedged fpm write
donaldsharp Dec 14, 2023
61af06c
zebra: Use event_add_event instead of _timer
donaldsharp Dec 14, 2023
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29 changes: 26 additions & 3 deletions zebra/dplane_fpm_nl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,12 @@
#define SOUTHBOUND_DEFAULT_ADDR INADDR_LOOPBACK
#define SOUTHBOUND_DEFAULT_PORT 2620

/*
* Time in seconds that if the other end is not responding
* something terrible has gone wrong. Let's fix that.
*/
#define DPLANE_FPM_NL_WEDGIE_TIME 15
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excellent - has to go down as one of the best token names in all of FRR


/**
* FPM header:
* {
Expand Down Expand Up @@ -93,6 +99,7 @@ struct fpm_nl_ctx {
struct event *t_event;
struct event *t_nhg;
struct event *t_dequeue;
struct event *t_wedged;

/* zebra events. */
struct event *t_lspreset;
Expand Down Expand Up @@ -1367,6 +1374,18 @@ static void fpm_rmac_reset(struct event *t)
&fnc->t_rmacwalk);
}

static void fpm_process_wedged(struct event *t)
{
struct fpm_nl_ctx *fnc = EVENT_ARG(t);

zlog_warn("%s: Connection unable to write to peer for over %u seconds, resetting",
__func__, DPLANE_FPM_NL_WEDGIE_TIME);

atomic_fetch_add_explicit(&fnc->counters.connection_errors, 1,
memory_order_relaxed);
FPM_RECONNECT(fnc);
}

static void fpm_process_queue(struct event *t)
{
struct fpm_nl_ctx *fnc = EVENT_ARG(t);
Expand Down Expand Up @@ -1411,9 +1430,13 @@ static void fpm_process_queue(struct event *t)
processed_contexts, memory_order_relaxed);

/* Re-schedule if we ran out of buffer space */
if (no_bufs)
event_add_timer(fnc->fthread->master, fpm_process_queue, fnc, 0,
if (no_bufs) {
event_add_event(fnc->fthread->master, fpm_process_queue, fnc, 0,
&fnc->t_dequeue);
event_add_timer(fnc->fthread->master, fpm_process_wedged, fnc,
DPLANE_FPM_NL_WEDGIE_TIME, &fnc->t_wedged);
} else
EVENT_OFF(fnc->t_wedged);

/*
* Let the dataplane thread know if there are items in the
Expand Down Expand Up @@ -1617,7 +1640,7 @@ static int fpm_nl_process(struct zebra_dplane_provider *prov)
if (atomic_load_explicit(&fnc->counters.ctxqueue_len,
memory_order_relaxed)
> 0)
event_add_timer(fnc->fthread->master, fpm_process_queue, fnc, 0,
event_add_event(fnc->fthread->master, fpm_process_queue, fnc, 0,
&fnc->t_dequeue);

/* Ensure dataplane thread is rescheduled if we hit the work limit */
Expand Down
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