[PATCH 4.9 164/172] infiniband: hns: avoid gcc-7.0.1 warning for uninitialized data

From: Greg Kroah-Hartman
Date: Mon Jul 03 2017 - 10:11:16 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: Arnd Bergmann <arnd@xxxxxxxx>

commit 5b0ff9a00755d4d9c209033a77f1ed8f3186fe5c upstream.

hns_roce_v1_cq_set_ci() calls roce_set_bit() on an uninitialized field,
which will then change only a few of its bits, causing a warning with
the latest gcc:

infiniband/hw/hns/hns_roce_hw_v1.c: In function 'hns_roce_v1_cq_set_ci':
infiniband/hw/hns/hns_roce_hw_v1.c:1854:23: error: 'doorbell[1]' is used uninitialized in this function [-Werror=uninitialized]
roce_set_bit(doorbell[1], ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_HW_SYNS_S, 1);

The code is actually correct since we always set all bits of the
port_vlan field, but gcc correctly points out that the first
access does contain uninitialized data.

This initializes the field to zero first before setting the
individual bits.

Fixes: 9a4435375cd1 ("IB/hns: Add driver files for hns RoCE driver")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/infiniband/hw/hns/hns_roce_hw_v1.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hw_v1.c
@@ -1267,6 +1267,7 @@ void hns_roce_v1_cq_set_ci(struct hns_ro
u32 doorbell[2];

doorbell[0] = cons_index & ((hr_cq->cq_depth << 1) - 1);
+ doorbell[1] = 0;
roce_set_bit(doorbell[1], ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_HW_SYNS_S, 1);
roce_set_field(doorbell[1], ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_CMD_M,