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From:   Arnd Bergmann <arnd@arndb.de>
To:     Ariel Elior <aelior@marvell.com>, GR-everest-linux-l2@marvell.com,
        "David S. Miller" <davem@davemloft.net>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Ariel Elior <ariel.elior@marvell.com>,
        Michal Kalderon <michal.kalderon@marvell.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Denis Bolotin <dbolotin@marvell.com>,
        Tomer Tayar <tomer.tayar@cavium.com>,
        Sudarsana Reddy Kalluru <skalluru@marvell.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] qed: Fix -Wmaybe-uninitialized false positive
Date:   Mon, 17 Jun 2019 15:04:49 +0200
Message-Id: <20190617130504.1906523-1-arnd@arndb.de>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

A previous attempt to shut up the uninitialized variable use
warning was apparently insufficient. When CONFIG_PROFILE_ANNOTATED_BRANCHES
is set, gcc-8 still warns, because the unlikely() check in DP_NOTICE()
causes it to no longer track the state of all variables correctly:

drivers/net/ethernet/qlogic/qed/qed_dev.c: In function 'qed_llh_set_ppfid_affinity':
drivers/net/ethernet/qlogic/qed/qed_dev.c:798:47: error: 'abs_ppfid' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  addr = NIG_REG_PPF_TO_ENGINE_SEL + abs_ppfid * 0x4;
                                     ~~~~~~~~~~^~~~~

This is not a nice workaround, but always initializing the output from
qed_llh_abs_ppfid() at least shuts up the false positive reliably.

Fixes: 79284adeb99e ("qed: Add llh ppfid interface and 100g support for offload protocols")
Fixes: 8e2ea3ea9625 ("qed: Fix static checker warning")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/qlogic/qed/qed_dev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_dev.c b/drivers/net/ethernet/qlogic/qed/qed_dev.c
index eec7cb65c7e6..a1ebc2b1ca0b 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_dev.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_dev.c
@@ -652,6 +652,7 @@ static int qed_llh_abs_ppfid(struct qed_dev *cdev, u8 ppfid, u8 *p_abs_ppfid)
 		DP_NOTICE(cdev,
 			  "ppfid %d is not valid, available indices are 0..%hhd\n",
 			  ppfid, p_llh_info->num_ppfid - 1);
+		*p_abs_ppfid = 0;
 		return -EINVAL;
 	}
 
-- 
2.20.0