From 6b79dc9ac30843b8af9a23c1055b83e7997e5b6a Mon Sep 17 00:00:00 2001
From: "Wilson W.K. Thong" <wilsonthong@astri.org>
Date: Wed, 21 Dec 2016 10:29:47 +0800
Subject: [PATCH] fixing crash due to de-qeueueing the same PDCP SDU twice by
two different threads
see issue #164
---
openair2/LAYER2/PDCP_v10.1.0/pdcp_fifo.c | 62 +++++++++++++++++++-----
1 file changed, 51 insertions(+), 11 deletions(-)
diff --git a/openair2/LAYER2/PDCP_v10.1.0/pdcp_fifo.c b/openair2/LAYER2/PDCP_v10.1.0/pdcp_fifo.c
index 3a99c9acca..8a73c36728 100644
--- a/openair2/LAYER2/PDCP_v10.1.0/pdcp_fifo.c
+++ b/openair2/LAYER2/PDCP_v10.1.0/pdcp_fifo.c
@@ -41,6 +41,7 @@ extern int otg_enabled;
#include "pdcp_primitives.h"
#ifdef USER_MODE
+#include <pthread.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
@@ -90,6 +91,21 @@ extern Packet_OTG_List_t *otg_pdcp_buffer;
# include "gtpv1u_eNB_task.h"
#endif
+/* Prevent de-queueing the same PDCP SDU from the queue twice
+ * by multiple threads. This has happened in TDD when thread-odd
+ * is flushing a PDCP SDU after UE_RX() processing; whereas
+ * thread-even is at a special-subframe, skips the UE_RX() process
+ * and goes straight to the PDCP SDU flushing. The 2nd flushing
+ * dequeues the same SDU again causing unexpected behavior.
+ *
+ * comment out the MACRO below to disable this protection
+ */
+#define PDCP_SDU_FLUSH_LOCK
+
+#ifdef PDCP_SDU_FLUSH_LOCK
+static pthread_mutex_t mtex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
pdcp_data_req_header_t pdcp_read_header_g;
//-----------------------------------------------------------------------------
@@ -97,21 +113,13 @@ int pdcp_fifo_flush_sdus(const protocol_ctxt_t* const ctxt_pP)
{
//-----------------------------------------------------------------------------
- mem_block_t *sdu_p = list_get_head (&pdcp_sdu_list);
- int bytes_wrote = 0;
- int pdcp_nb_sdu_sent = 0;
- uint8_t cont = 1;
-#if defined(LINK_ENB_PDCP_TO_GTPV1U)
- //MessageDef *message_p = NULL;
-#endif
-
-#if defined(PDCP_USE_NETLINK) && defined(LINUX)
+//#if defined(PDCP_USE_NETLINK) && defined(LINUX)
int ret = 0;
-#endif
+//#endif
#ifdef DEBUG_PDCP_FIFO_FLUSH_SDU
#define THREAD_NAME_LEN 16
- char threadname[THREAD_NAME_LEN];
+ static char threadname[THREAD_NAME_LEN];
ret = pthread_getname_np(pthread_self(), threadname, THREAD_NAME_LEN);
if (ret != 0)
{
@@ -121,6 +129,34 @@ int pdcp_fifo_flush_sdus(const protocol_ctxt_t* const ctxt_pP)
#undef THREAD_NAME_LEN
#endif
+#ifdef PDCP_SDU_FLUSH_LOCK
+ ret = pthread_mutex_trylock(&mtex);
+ if (ret == EBUSY) {
+#ifdef DEBUG_PDCP_FIFO_FLUSH_SDU
+ LOG_W(PDCP, "[%s] at SFN/SF=%d/%d wait for PDCP FIFO to be unlocked\n",
+ threadname, ctxt_pP->frame, ctxt_pP->subframe);
+#endif
+ if (pthread_mutex_lock(&mtex)) {
+ exit_fun("PDCP_SDU_FLUSH_LOCK lock error!");
+ }
+#ifdef DEBUG_PDCP_FIFO_FLUSH_SDU
+ LOG_I(PDCP, "[%s] at SFN/SF=%d/%d PDCP FIFO is unlocked\n",
+ threadname, ctxt_pP->frame, ctxt_pP->subframe);
+#endif
+ } else if (ret != 0) {
+ exit_fun("PDCP_SDU_FLUSH_LOCK trylock error!");
+ }
+
+#endif
+
+ mem_block_t *sdu_p = list_get_head (&pdcp_sdu_list);
+ int bytes_wrote = 0;
+ int pdcp_nb_sdu_sent = 0;
+ uint8_t cont = 1;
+#if defined(LINK_ENB_PDCP_TO_GTPV1U)
+ //MessageDef *message_p = NULL;
+#endif
+
VCD_SIGNAL_DUMPER_DUMP_FUNCTION_BY_NAME( VCD_SIGNAL_DUMPER_FUNCTIONS_PDCP_FIFO_FLUSH, 1 );
while (sdu_p && cont) {
@@ -332,6 +368,10 @@ int pdcp_fifo_flush_sdus(const protocol_ctxt_t* const ctxt_pP)
#endif //PDCP_USE_RT_FIFO
+#ifdef PDCP_SDU_FLUSH_LOCK
+ if (pthread_mutex_unlock(&mtex)) exit_fun("PDCP_SDU_FLUSH_LOCK unlock error!");
+#endif
+
return pdcp_nb_sdu_sent;
}
--
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