transport: Prevent sticking in waiting for response
When the connection has an issue, one request may not receive the
response. The pldm_transport_send_recv_msg should not be stuck in
while loop to wait for the response.
As the section "Requirements for requesters" in DSP0240 PLDM Base
specs, the maximum value of "Time-out waiting for a response" PT2max
is 4800ms. This commit uses that time out to prevent
pldm_transport_send_recv_msg from forever waiting for the response.
Signed-off-by: Dung Cao <dung@os.amperecomputing.com>
Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
Change-Id: I70b62b1ff30a8a715716db43867b479a5b214dfa
diff --git a/src/transport/transport.c b/src/transport/transport.c
index c8be844..d4608a7 100644
--- a/src/transport/transport.c
+++ b/src/transport/transport.c
@@ -3,10 +3,15 @@
#include "libpldm/requester/pldm.h"
#include "transport.h"
+#include <errno.h>
+#include <limits.h>
#ifdef PLDM_HAS_POLL
#include <poll.h>
#endif
+#include <stdbool.h>
#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
#include <unistd.h>
#ifndef PLDM_HAS_POLL
@@ -98,33 +103,108 @@
return PLDM_REQUESTER_SUCCESS;
}
+static void timespec_to_timeval(const struct timespec *ts, struct timeval *tv)
+{
+ tv->tv_sec = ts->tv_sec;
+ tv->tv_usec = ts->tv_nsec / 1000;
+}
+
+/* Overflow safety must be upheld before call */
+static long timeval_to_msec(const struct timeval *tv)
+{
+ return tv->tv_sec * 1000 + tv->tv_usec / 1000;
+}
+
+/* If calculations on `tv` don't overflow then operations on derived
+ * intervals can't either.
+ */
+static bool timeval_is_valid(const struct timeval *tv)
+{
+ if (tv->tv_sec < 0 || tv->tv_usec < 0 || tv->tv_usec >= 1000000) {
+ return false;
+ }
+
+ if (tv->tv_sec > (LONG_MAX - tv->tv_usec / 1000) / 1000) {
+ return false;
+ }
+
+ return true;
+}
+
+static int clock_gettimeval(clockid_t clockid, struct timeval *tv)
+{
+ struct timespec now;
+ int rc;
+
+ rc = clock_gettime(clockid, &now);
+ if (rc < 0) {
+ return rc;
+ }
+
+ timespec_to_timeval(&now, tv);
+
+ return 0;
+}
+
pldm_requester_rc_t
pldm_transport_send_recv_msg(struct pldm_transport *transport, pldm_tid_t tid,
const void *pldm_req_msg, size_t req_msg_len,
void **pldm_resp_msg, size_t *resp_msg_len)
{
+ /**
+ * Section "Requirements for requesters" in DSP0240, define the Time-out
+ * waiting for a response of the requester.
+ * PT2max = PT3min - 2*PT4max = 4800ms
+ */
+ static const struct timeval max_response_interval = {
+ .tv_sec = 4, .tv_usec = 800000
+ };
+ struct timeval remaining;
+ struct timeval now;
+ struct timeval end;
+ pldm_requester_rc_t rc;
+ int ret;
+
if (!resp_msg_len) {
return PLDM_REQUESTER_INVALID_SETUP;
}
- pldm_requester_rc_t rc = pldm_transport_send_msg(
- transport, tid, pldm_req_msg, req_msg_len);
+ rc = pldm_transport_send_msg(transport, tid, pldm_req_msg, req_msg_len);
if (rc != PLDM_REQUESTER_SUCCESS) {
return rc;
}
- while (1) {
- rc = pldm_transport_poll(transport, -1);
+ ret = clock_gettimeval(CLOCK_MONOTONIC, &now);
+ if (ret < 0) {
+ return PLDM_REQUESTER_POLL_FAIL;
+ }
+
+ timeradd(&now, &max_response_interval, &end);
+ if (!timeval_is_valid(&end)) {
+ return PLDM_REQUESTER_POLL_FAIL;
+ }
+
+ do {
+ timersub(&end, &now, &remaining);
+ /* 0 <= `timeval_to_msec()` <= 4800, and 4800 < INT_MAX */
+ rc = pldm_transport_poll(transport,
+ (int)(timeval_to_msec(&remaining)));
if (rc != PLDM_REQUESTER_SUCCESS) {
- break;
+ return rc;
}
+
rc = pldm_transport_recv_msg(transport, tid, pldm_resp_msg,
resp_msg_len);
if (rc == PLDM_REQUESTER_SUCCESS) {
- break;
+ return rc;
}
- }
- return rc;
+ ret = clock_gettimeval(CLOCK_MONOTONIC, &now);
+ if (ret < 0) {
+ return PLDM_REQUESTER_POLL_FAIL;
+ }
+ } while (!timercmp(&now, &end, <));
+
+ return PLDM_REQUESTER_RECV_FAIL;
}