diff options
Diffstat (limited to 'src/host/trxcon/sched_trx.c')
| -rw-r--r-- | src/host/trxcon/sched_trx.c | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/src/host/trxcon/sched_trx.c b/src/host/trxcon/sched_trx.c index 9195b336..0025e0cc 100644 --- a/src/host/trxcon/sched_trx.c +++ b/src/host/trxcon/sched_trx.c @@ -625,7 +625,7 @@ static int subst_frame_loss(struct trx_lchan_state *lchan, { const struct trx_multiframe *mf; const struct trx_frame *fp; - unsigned int elapsed, i; + int elapsed, i; /* Wait until at least one TDMA frame is processed */ if (lchan->tdma.num_proc == 0) @@ -634,10 +634,28 @@ static int subst_frame_loss(struct trx_lchan_state *lchan, /* Short alias for the current multiframe */ mf = lchan->ts->mf_layout; - /* How many frames elapsed since the last one? */ - elapsed = GSM_TDMA_FN_SUB(fn, lchan->tdma.last_proc); + /* Calculate how many frames elapsed since the last received one. + * The algorithm is based on GSM::FNDelta() from osmo-trx. */ + elapsed = fn - lchan->tdma.last_proc; + if (elapsed >= GSM_TDMA_HYPERFRAME / 2) + elapsed -= GSM_TDMA_HYPERFRAME; + else if (elapsed < -GSM_TDMA_HYPERFRAME / 2) + elapsed += GSM_TDMA_HYPERFRAME; + + /* Check TDMA frame order (wrong order is possible with fake_trx.py, see OS#4658) */ + if (elapsed < 0) { + /* This burst has already been substituted by a dummy burst (all bits set to zero), + * so better drop it. Otherwise we risk to get undefined behavior in handler(). */ + LOGP(DSCHD, LOGL_ERROR, "(%s) Rx burst with fn=%u older than the last " + "processed fn=%u (see OS#4658) => dropping\n", + trx_lchan_desc[lchan->type].name, + fn, lchan->tdma.last_proc); + return -EALREADY; + } + + /* Check how many frames we (potentially) need to compensate */ if (elapsed > mf->period) { - LOGP(DSCHD, LOGL_NOTICE, "Too many (>%u) contiguous TDMA frames elapsed (%u) " + LOGP(DSCHD, LOGL_NOTICE, "Too many (>%u) contiguous TDMA frames elapsed (%d) " "since the last processed fn=%u (current %u)\n", mf->period, elapsed, lchan->tdma.last_proc, fn); return -EIO; @@ -687,6 +705,7 @@ int sched_trx_handle_rx_burst(struct trx_instance *trx, uint8_t tn, trx_lchan_rx_func *handler; enum trx_lchan_type chan; uint8_t offset, bid; + int rc; /* Check whether required timeslot is allocated and configured */ ts = trx->ts_list[tn]; @@ -720,7 +739,9 @@ int sched_trx_handle_rx_burst(struct trx_instance *trx, uint8_t tn, return 0; /* Compensate lost TDMA frames (if any) */ - subst_frame_loss(lchan, handler, fn); + rc = subst_frame_loss(lchan, handler, fn); + if (rc == -EALREADY) + return rc; /* Perform A5/X decryption if required */ if (lchan->a5.algo) |