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Fixed MSTP dropped packets on Linux by fixing usage of ptheads condition variable. Turns out that condition variables cannot be used on their own. They need to be paired with a shared state such as a flag variable protected by a mutex.

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This commit is contained in:
skarg
2014-11-15 22:03:17 +00:00
parent aa124bc091
commit 781da0b53b
1 changed files with 29 additions and 21 deletions
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bacnet-stack/ports/linux/dlmstp.c
+29 -21
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@@ -38,6 +38,7 @@
#include "npdu.h"
#include "bits.h"
#include "ringbuf.h"
#include "debug.h"
/* OS Specific include */
#include "net.h"
@@ -89,12 +90,12 @@ static RING_BUFFER PDU_Queue;
/* that a node must wait for a station to begin replying to a */
/* confirmed request: 255 milliseconds. (Implementations may use */
/* larger values for this timeout, not to exceed 300 milliseconds.) */
static uint16_t Treply_timeout = 260;
static uint16_t Treply_timeout = 300;
/* The minimum time without a DataAvailable or ReceiveError event that a */
/* node must wait for a remote node to begin using a token or replying to */
/* a Poll For Master frame: 20 milliseconds. (Implementations may use */
/* larger values for this timeout, not to exceed 100 milliseconds.) */
static uint8_t Tusage_timeout = 60;
static uint8_t Tusage_timeout = 100;
/* Timer that indicates line silence - and functions */
static struct timeval start;
@@ -181,31 +182,30 @@ uint16_t dlmstp_receive(
{ /* milliseconds to wait for a packet */
uint16_t pdu_len = 0;
struct timespec abstime;
int rv = 0;
(void) max_pdu;
/* see if there is a packet available, and a place
to put the reply (if necessary) and process it */
pthread_mutex_lock(&Receive_Packet_Mutex);
get_abstime(&abstime, timeout);
rv = pthread_cond_timedwait(&Receive_Packet_Flag, &Receive_Packet_Mutex,
pthread_cond_timedwait(&Receive_Packet_Flag, &Receive_Packet_Mutex,
&abstime);
if (rv == 0) {
if (Receive_Packet.ready) {
if (Receive_Packet.pdu_len) {
MSTP_Packets++;
if (src) {
memmove(src, &Receive_Packet.address,
sizeof(Receive_Packet.address));
}
if (pdu) {
memmove(pdu, &Receive_Packet.pdu,
sizeof(Receive_Packet.pdu));
}
pdu_len = Receive_Packet.pdu_len;
if (Receive_Packet.ready) {
if (Receive_Packet.pdu_len) {
MSTP_Packets++;
if (src) {
memmove(src, &Receive_Packet.address,
sizeof(Receive_Packet.address));
}
Receive_Packet.ready = false;
if (pdu) {
memmove(pdu, &Receive_Packet.pdu,
sizeof(Receive_Packet.pdu));
}
pdu_len = Receive_Packet.pdu_len;
}
Receive_Packet.ready = false;
}
pthread_mutex_unlock(&Receive_Packet_Mutex);
return pdu_len;
}
@@ -246,7 +246,7 @@ static void *dlmstp_master_fsm_task(
}
}
if (run_master) {
if (MSTP_Port.This_Station <= DEFAULT_MAX_MASTER) {
if (MSTP_Port.This_Station <= 127) {
while (MSTP_Master_Node_FSM(&MSTP_Port)) {
/* do nothing while immediate transitioning */
}
@@ -290,11 +290,18 @@ uint16_t MSTP_Put_Receive(
{
uint16_t pdu_len = 0;
if (!Receive_Packet.ready) {
pthread_mutex_lock(&Receive_Packet_Mutex);
if (Receive_Packet.ready) {
debug_printf("MS/TP: Dropped! Not Ready.\n");
} else {
/* bounds check - maybe this should send an abort? */
pdu_len = mstp_port->DataLength;
if (pdu_len > sizeof(Receive_Packet.pdu))
if (pdu_len > sizeof(Receive_Packet.pdu)) {
pdu_len = sizeof(Receive_Packet.pdu);
}
if (pdu_len == 0) {
debug_printf("MS/TP: PDU Length is 0!\n");
}
memmove((void *) &Receive_Packet.pdu[0],
(void *) &mstp_port->InputBuffer[0], pdu_len);
dlmstp_fill_bacnet_address(&Receive_Packet.address,
@@ -303,6 +310,7 @@ uint16_t MSTP_Put_Receive(
Receive_Packet.ready = true;
pthread_cond_signal(&Receive_Packet_Flag);
}
pthread_mutex_unlock(&Receive_Packet_Mutex);
return pdu_len;
}