linux-kernel - [PATCH 4.9 009/157] staging: wlan-ng: Avoid bitwise vs logical OR warning in hfa384x_usb

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 24 Jan 2022 19:41:39 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH 4.9 009/157] staging: wlan-ng: Avoid bitwise vs logical OR warning in hfa384x_usb_throttlefn()

From: Nathan Chancellor <nathan@...nel.org>

commit 502408a61f4b7eb4713f44bd77f4a48e6cb1b59a upstream.

A new warning in clang points out a place in this file where a bitwise
OR is being used with boolean expressions:

In file included from drivers/staging/wlan-ng/prism2usb.c:2:
drivers/staging/wlan-ng/hfa384x_usb.c:3787:7: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical]
            ((test_and_clear_bit(THROTTLE_RX, &hw->usb_flags) &&
            ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/staging/wlan-ng/hfa384x_usb.c:3787:7: note: cast one or both operands to int to silence this warning
1 warning generated.

The comment explains that short circuiting here is undesirable, as the
calls to test_and_{clear,set}_bit() need to happen for both sides of the
expression.

Clang's suggestion would work to silence the warning but the readability
of the expression would suffer even more. To clean up the warning and
make the block more readable, use a variable for each side of the
bitwise expression.

Link: https://github.com/ClangBuiltLinux/linux/issues/1478
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
Link: https://lore.kernel.org/r/20211014215703.3705371-1-nathan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/staging/wlan-ng/hfa384x_usb.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

--- a/drivers/staging/wlan-ng/hfa384x_usb.c
+++ b/drivers/staging/wlan-ng/hfa384x_usb.c
@@ -3848,18 +3848,18 @@ static void hfa384x_usb_throttlefn(unsig
 
 	spin_lock_irqsave(&hw->ctlxq.lock, flags);
 
-	/*
-	 * We need to check BOTH the RX and the TX throttle controls,
-	 * so we use the bitwise OR instead of the logical OR.
-	 */
 	pr_debug("flags=0x%lx\n", hw->usb_flags);
-	if (!hw->wlandev->hwremoved &&
-	    ((test_and_clear_bit(THROTTLE_RX, &hw->usb_flags) &&
-	      !test_and_set_bit(WORK_RX_RESUME, &hw->usb_flags)) |
-	     (test_and_clear_bit(THROTTLE_TX, &hw->usb_flags) &&
-	      !test_and_set_bit(WORK_TX_RESUME, &hw->usb_flags))
-	    )) {
-		schedule_work(&hw->usb_work);
+	if (!hw->wlandev->hwremoved) {
+		bool rx_throttle = test_and_clear_bit(THROTTLE_RX, &hw->usb_flags) &&
+				   !test_and_set_bit(WORK_RX_RESUME, &hw->usb_flags);
+		bool tx_throttle = test_and_clear_bit(THROTTLE_TX, &hw->usb_flags) &&
+				   !test_and_set_bit(WORK_TX_RESUME, &hw->usb_flags);
+		/*
+		 * We need to check BOTH the RX and the TX throttle controls,
+		 * so we use the bitwise OR instead of the logical OR.
+		 */
+		if (rx_throttle | tx_throttle)
+			schedule_work(&hw->usb_work);
 	}
 
 	spin_unlock_irqrestore(&hw->ctlxq.lock, flags);