linux-kernel - [PATCH] net/mlx4: suppress 'may be used uninitialized' warning

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Message-Id: <20170418062135.76698-1-gthelen@google.com>
Date:   Mon, 17 Apr 2017 23:21:35 -0700
From:   Greg Thelen <gthelen@...gle.com>
To:     Or Gerlitz <ogerlitz@...lanox.com>,
        Jack Morgenstein <jackm@....mellanox.co.il>,
        Matan Barak <matanb@...lanox.com>
Cc:     Ido Shamay <idos@...lanox.com>,
        Yishai Hadas <yishaih@...lanox.com>,
        Amir Vadai <amirv@...lanox.com>,
        Roland Dreier <roland@...estorage.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg Thelen <gthelen@...gle.com>
Subject: [PATCH] net/mlx4: suppress 'may be used uninitialized' warning

gcc 4.8.4 complains that mlx4_SW2HW_MPT_wrapper() uses an uninitialized
'mpt' variable:
  drivers/net/ethernet/mellanox/mlx4/resource_tracker.c: In function 'mlx4_SW2HW_MPT_wrapper':
  drivers/net/ethernet/mellanox/mlx4/resource_tracker.c:2802:12: warning: 'mpt' may be used uninitialized in this function [-Wmaybe-uninitialized]
     mpt->mtt = mtt;

I think this warning is a false complaint.  mpt is only used when
mr_res_start_move_to() return zero, and in all such cases it initializes
mpt.  But apparently gcc cannot see that.

Initialize mpt to avoid the warning.

Signed-off-by: Greg Thelen <gthelen@...gle.com>
---
 drivers/net/ethernet/mellanox/mlx4/resource_tracker.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c b/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c
index d8d5d161b8c7..4aa29ee93013 100644
--- a/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c
+++ b/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c
@@ -2749,7 +2749,7 @@ int mlx4_SW2HW_MPT_wrapper(struct mlx4_dev *dev, int slave,
 	int err;
 	int index = vhcr->in_modifier;
 	struct res_mtt *mtt;
-	struct res_mpt *mpt;
+	struct res_mpt *mpt = NULL;
 	int mtt_base = mr_get_mtt_addr(inbox->buf) / dev->caps.mtt_entry_sz;
 	int phys;
 	int id;
-- 
2.12.2.762.g0e3151a226-goog