[PATCH for-next 04/11] IB/hfi1: Fix a wrapping test to insure the correct timeout

Dennis Dalessandro
2017-11-06T14:38:38Z

From: Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

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-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
drivers/infiniband/hw/hfi1/mad.c | 6 +++---
drivers/infiniband/hw/hfi1/mad.h | 2 +-
drivers/infiniband/hw/hfi1/rc.c | 2 +-
3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/mad.c b/drivers/infiniband/hw/hfi1/mad.c
index e648f58..0a867e5 100644
--- a/drivers/infiniband/hw/hfi1/mad.c
+++ b/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,
diff --git a/drivers/infiniband/hw/hfi1/mad.h b/drivers/infiniband/hw/hfi1/mad.h
index a4f8ac1..c4938f3 100644
--- a/drivers/infiniband/hw/hfi1/mad.h
+++ b/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 {
diff --git a/drivers/infiniband/hw/hfi1/rc.c b/drivers/infiniband/hw/hfi1/rc.c
index 32d7bbe..3f21b05 100644
--- a/drivers/infiniband/hw/hfi1/rc.c
+++ b/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);