IB/hfi1: Fix a wrapping test to insure the correct timeout

The "2 * UINT_MAX"  statement:
	if ((u64)(ts - cce->timestamp) > 2 * UINT_MAX) {

is equivalent to:
	if ((u64)(ts - cce->timestamp) > UINT_MAX - 1) {

This results in a premature timeout of the cong log entry.

Fix by using unsigned 64 bit integers, removing casts, and using
an algebraic equivalent test to avoid the "2 * UINT_MAX" issue.

Also make use of kernel API to get nanoseconds instead of
open coding.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/mad.c

@@ -3760,7 +3760,7 @@ static int __subn_get_opa_hfi1_cong_log(struct opa_smp *smp, u32 am,
 	struct hfi1_ibport *ibp = to_iport(ibdev, port);
 	struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
 	struct opa_hfi1_cong_log *cong_log = (struct opa_hfi1_cong_log *)data;
-	s64 ts;
+	u64 ts;
 	int i;
 
 	if (am || smp_length_check(sizeof(*cong_log), max_len)) {
@@ -3778,7 +3778,7 @@ static int __subn_get_opa_hfi1_cong_log(struct opa_smp *smp, u32 am,
 	       ppd->threshold_cong_event_map,
 	       sizeof(cong_log->threshold_cong_event_map));
 	/* keep timestamp in units of 1.024 usec */
-	ts = ktime_to_ns(ktime_get()) / 1024;
+	ts = ktime_get_ns() / 1024;
 	cong_log->current_time_stamp = cpu_to_be32(ts);
 	for (i = 0; i < OPA_CONG_LOG_ELEMS; i++) {
 		struct opa_hfi1_cong_log_event_internal *cce =
@@ -3790,7 +3790,7 @@ static int __subn_get_opa_hfi1_cong_log(struct opa_smp *smp, u32 am,
 		 * required to wrap the counter are supposed to
 		 * be zeroed (CA10-49 IBTA, release 1.2.1, V1).
 		 */
-		if ((u64)(ts - cce->timestamp) > (2 * UINT_MAX))
+		if ((ts - cce->timestamp) / 2 > U32_MAX)
 			continue;
 		memcpy(cong_log->events[i].local_qp_cn_entry, &cce->lqpn, 3);
 		memcpy(cong_log->events[i].remote_qp_number_cn_entry,

drivers/infiniband/hw/hfi1/mad.h

@@ -239,7 +239,7 @@ struct opa_hfi1_cong_log_event_internal {
 	u8 sl;
 	u8 svc_type;
 	u32 rlid;
-	s64 timestamp; /* wider than 32 bits to detect 32 bit rollover */
+	u64 timestamp; /* wider than 32 bits to detect 32 bit rollover */
 };
 
 struct opa_hfi1_cong_log_event {

drivers/infiniband/hw/hfi1/rc.c

@@ -1965,7 +1965,7 @@ static void log_cca_event(struct hfi1_pportdata *ppd, u8 sl, u32 rlid,
 	cc_event->svc_type = svc_type;
 	cc_event->rlid = rlid;
 	/* keep timestamp in units of 1.024 usec */
-	cc_event->timestamp = ktime_to_ns(ktime_get()) / 1024;
+	cc_event->timestamp = ktime_get_ns() / 1024;
 
 	spin_unlock_irqrestore(&ppd->cc_log_lock, flags);
 }