Patch "infiniband: hns: avoid gcc-7.0.1 warning for uninitialized data" has been added to the 4.9-stable tree

Patch "infiniband: hns: avoid gcc-7.0.1 warning for uninitialized data" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    infiniband: hns: avoid gcc-7.0.1 warning for uninitialized data

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     infiniband-hns-avoid-gcc-7.0.1-warning-for-uninitialized-data.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 5b0ff9a00755d4d9c209033a77f1ed8f3186fe5c Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Fri, 24 Mar 2017 23:02:48 +0100
Subject: infiniband: hns: avoid gcc-7.0.1 warning for uninitialized data

From: Arnd Bergmann <arnd@arndb.de>

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@arndb.de>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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,
 		       ROCEE_DB_OTHERS_H_ROCEE_DB_OTH_CMD_S, 3);


Patches currently in stable-queue which might be from arnd@arndb.de are

queue-4.9/infiniband-hns-avoid-gcc-7.0.1-warning-for-uninitialized-data.patch
queue-4.9/objtool-fix-another-gcc-jump-table-detection-issue.patch
queue-4.9/arm64-dts-meson-gxbb-odroidc2-fix-gbe-tx-link-breakage.patch