linux-kernel - [PATCH net-next v2] ptp: ocp: Avoid operator precedence warning in ptp_ocp_summary

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Message-Id: <20210917045204.1385801-1-nathan@kernel.org>
Date:   Thu, 16 Sep 2021 21:52:05 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Richard Cochran <richardcochran@...il.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH net-next v2] ptp: ocp: Avoid operator precedence warning in ptp_ocp_summary_show()

Clang warns twice:

drivers/ptp/ptp_ocp.c:2065:16: error: operator '?:' has lower precedence
than '&'; '&' will be evaluated first
[-Werror,-Wbitwise-conditional-parentheses]
                           on & map ? " ON" : "OFF", src);
                           ~~~~~~~~ ^
drivers/ptp/ptp_ocp.c:2065:16: note: place parentheses around the '&'
expression to silence this warning
                           on & map ? " ON" : "OFF", src);
                                    ^
                           (       )
drivers/ptp/ptp_ocp.c:2065:16: note: place parentheses around the '?:'
expression to evaluate it first
                           on & map ? " ON" : "OFF", src);
                                    ^

on and map are both booleans so this should be a logical AND, which
clears up the operator precedence issue.

Fixes: a62a56d04e63 ("ptp: ocp: Enable 4th timestamper / PPS generator")
Link: https://github.com/ClangBuiltLinux/linux/issues/1457
Suggested-by: Jonathan Lemon <jonathan.lemon@...il.com>
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---

v1 -> v2: https://lore.kernel.org/r/20210916194351.3860836-1-nathan@kernel.org/

* Change fix from adding parentheses to moving from bitwise to logical
  AND. Thanks to Jonathan for catching that both operands were boolean,
  which I unfortunately missed.

 drivers/ptp/ptp_ocp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 844b1401cc5d..c26708f486cf 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -2062,11 +2062,11 @@ ptp_ocp_summary_show(struct seq_file *s, void *data)
 		on = ioread32(&ts_reg->enable);
 		map = !!(bp->pps_req_map & OCP_REQ_TIMESTAMP);
 		seq_printf(s, "%7s: %s, src: %s\n", "TS3",
-			   on & map ? " ON" : "OFF", src);
+			   on && map ? " ON" : "OFF", src);
 
 		map = !!(bp->pps_req_map & OCP_REQ_PPS);
 		seq_printf(s, "%7s: %s, src: %s\n", "PPS",
-			   on & map ? " ON" : "OFF", src);
+			   on && map ? " ON" : "OFF", src);
 	}
 
 	if (bp->irig_out) {

base-commit: 8dc84dcd7f74b50f81de3dbf6f6b5b146e3a8eea
-- 
2.33.0