[PATCH for-next 1/2] RDMA/hns: Add detailed comments for mb() call

Yixian Liu
2017-12-25T13:37:18Z

This patch adds more detailed comments when we call the
memory barrier function, such as rmb, wmb and mb. Three
mb() callers are deleted since they are unnecessary.

Signed-off-by: Yixian Liu <liuyixian-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
Signed-off-by: Lijun Ou <oulijun-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
---
drivers/infiniband/hw/hns/hns_roce_hw_v1.c | 19 ++++++++++++++-----
drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 22 +++++++++++-----------
2 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
index 6100ace..abcc64e 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
@@ -3963,7 +3963,10 @@ static void set_eq_cons_index_v1(struct hns_roce_eq *eq, int req_not)
{
roce_raw_write((eq->cons_index & HNS_ROCE_V1_CONS_IDX_M) |
(req_not << eq->log_entries), eq->doorbell);
- /* Memory barrier */
+
+ /* Make sure we update the consumer index of EQ before
+ * accessing it later
+ */
mb();
}

@@ -4156,13 +4159,16 @@ static int hns_roce_v1_aeq_int(struct hns_roce_dev *hr_dev,
int event_type;

while ((aeqe = next_aeqe_sw_v1(eq))) {
+
+ /* Make sure we read the AEQ entry after we have checked the
+ * ownership bit
+ */
+ rmb();
+
dev_dbg(dev, "aeqe = %p, aeqe->asyn.event_type = 0x%lx\n", aeqe,
roce_get_field(aeqe->asyn,
HNS_ROCE_AEQE_U32_4_EVENT_TYPE_M,
HNS_ROCE_AEQE_U32_4_EVENT_TYPE_S));
- /* Memory barrier */
- rmb();
-
event_type = roce_get_field(aeqe->asyn,
HNS_ROCE_AEQE_U32_4_EVENT_TYPE_M,
HNS_ROCE_AEQE_U32_4_EVENT_TYPE_S);
@@ -4260,7 +4266,10 @@ static int hns_roce_v1_ceq_int(struct hns_roce_dev *hr_dev,
u32 cqn;

while ((ceqe = next_ceqe_sw_v1(eq))) {
- /* Memory barrier */
+
+ /* Make sure we read CEQ entry after we have checked the
+ * ownership bit
+ */
rmb();
cqn = roce_get_field(ceqe->comp,
HNS_ROCE_CEQE_CEQE_COMP_CQN_M,
diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
index 04281d0..7f393f6 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
@@ -3200,7 +3200,9 @@ static void set_eq_cons_index_v2(struct hns_roce_eq *eq)

hns_roce_write64_k(doorbell, eq->doorbell);

- /* Memory barrier */
+ /* Make sure we update the consumer index of EQ before
+ * accessing it later
+ */
mb();

}
@@ -3384,7 +3386,10 @@ static int hns_roce_v2_aeq_int(struct hns_roce_dev *hr_dev,
int event_type;

while ((aeqe = next_aeqe_sw_v2(eq))) {
- /* Memory barrier */
+
+ /* Make sure we read AEQ entry after we have checked the
+ * ownership bit
+ */
rmb();

event_type = roce_get_field(aeqe->asyn,
@@ -3500,8 +3505,11 @@ static int hns_roce_v2_ceq_int(struct hns_roce_dev *hr_dev,

while ((ceqe = next_ceqe_sw_v2(eq))) {

- /* Memory barrier */
+ /* Make sure we read CEQ entry after we have checked the
+ * ownership bit
+ */
rmb();
+
cqn = roce_get_field(ceqe->comp,
HNS_ROCE_V2_CEQE_COMP_CQN_M,
HNS_ROCE_V2_CEQE_COMP_CQN_S);
@@ -3556,9 +3564,6 @@ static irqreturn_t hns_roce_v2_msix_interrupt_abn(int irq, void *dev_id)
roce_set_bit(int_st, HNS_ROCE_V2_VF_INT_ST_AEQ_OVERFLOW_S, 1);
roce_write(hr_dev, ROCEE_VF_ABN_INT_ST_REG, int_st);

- /* Memory barrier */
- mb();
-
roce_set_bit(int_en, HNS_ROCE_V2_VF_ABN_INT_EN_S, 1);
roce_write(hr_dev, ROCEE_VF_ABN_INT_EN_REG, int_en);

@@ -3569,9 +3574,6 @@ static irqreturn_t hns_roce_v2_msix_interrupt_abn(int irq, void *dev_id)
roce_set_bit(int_st, HNS_ROCE_V2_VF_INT_ST_BUS_ERR_S, 1);
roce_write(hr_dev, ROCEE_VF_ABN_INT_ST_REG, int_st);

- /* Memory barrier */
- mb();
-
roce_set_bit(int_en, HNS_ROCE_V2_VF_ABN_INT_EN_S, 1);
roce_write(hr_dev, ROCEE_VF_ABN_INT_EN_REG, int_en);

@@ -3582,8 +3584,6 @@ static irqreturn_t hns_roce_v2_msix_interrupt_abn(int irq, void *dev_id)
roce_set_bit(int_st, HNS_ROCE_V2_VF_INT_ST_OTHER_ERR_S, 1);
roce_write(hr_dev, ROCEE_VF_ABN_INT_ST_REG, int_st);

- /* Memory barrier */
- mb();
roce_set_bit(int_en, HNS_ROCE_V2_VF_ABN_INT_EN_S, 1);
roce_write(hr_dev, ROCEE_VF_ABN_INT_EN_REG, int_en);

--
1.9.1