linux-kernel - [PATCH] staging: gpib: Fix inadvertent negative shift

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Message-ID: <20250116110014.15577-1-dpenkler@gmail.com>
Date: Thu, 16 Jan 2025 12:00:14 +0100
From: Dave Penkler <dpenkler@...il.com>
To: gregkh@...uxfoundation.org,
	linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Dave Penkler <dpenkler@...il.com>
Subject: [PATCH] staging: gpib: Fix inadvertent negative shift

During the initial checkpatch cleanup, when removing blanks
after open parentheses, a minus sign in the argument of a shift
operation was deleted by mistake. This transformed a pre-decrement
operation into a negation.

The result of a negative shift is undefined and a warning was
signalled by sparse.

Restore the pre-decrement operation.

Fixes: 6c52d5e3cde2 ("staging: gpib: Add common include files for GPIB drivers")
Signed-off-by: Dave Penkler <dpenkler@...il.com>
---
 drivers/staging/gpib/include/amcc5920.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/gpib/include/amcc5920.h b/drivers/staging/gpib/include/amcc5920.h
index 766b3799223f..7a88bd282feb 100644
--- a/drivers/staging/gpib/include/amcc5920.h
+++ b/drivers/staging/gpib/include/amcc5920.h
@@ -22,7 +22,7 @@ static const int bits_per_region = 8;
 
 static inline uint32_t amcc_wait_state_bits(unsigned int region, unsigned int num_wait_states)
 {
-	return (num_wait_states & 0x7) << (-region * bits_per_region);
+	return (num_wait_states & 0x7) << (--region * bits_per_region);
 };
 
 enum amcc_prefetch_bits {
-- 
2.47.1