RE: [PATCH] qed: Fix -Wmaybe-uninitialized false positive

From: Arnd Bergmann <arnd@arndb.de>
Sent: Monday, June 17, 2019 4:05 PM

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