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[RFC,3/4] selftests/binderfs: Macro argument 'fd' may be better as '(fd)' to avoid precedence issues

Message ID 20240515010805.605511-4-xandfury@gmail.com
State New
Headers show
Series selftests/binderfs: Fixes to binderfs_test | expand

Commit Message

Abhinav Saxena May 15, 2024, 1:08 a.m. UTC 
Change the macro argument 'fd' to '(fd)' to avoid potential precedence
issues. Without parentheses, the macro expansion could lead to
unexpected behavior when used with an expression having different
precedence levels.

Example Code:

    #define CALC_SQR_BAD(x) (x*x)
    #define CALC_SQR_GOOD(x) ((x)*(x))

CALC_SQR_BAD(2+3) expands to 2+(3*3)+2, giving 11 as the incorrect
answer. Enclosing with parathesis CALC_SQR_GOOD(2+3) sets the correct
order of precedence and expands to (2+3)*(2+3), giving 25 as the
correct answer.

Signed-off-by: Abhinav Saxena <xandfury@gmail.com>
---
 .../testing/selftests/filesystems/binderfs/binderfs_test.c  | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--
2.34.1
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Patch

diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
index 4a149e3d4ba4..d5dba6c1e07f 100644
--- a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
+++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
@@ -30,11 +30,11 @@ 

 #define close_prot_errno_disarm(fd)      \
 	do {				 \
-		if (fd >= 0) {		 \
+		if ((fd) >= 0) {	 \
 			int _e_ = errno; \
-			close(fd);	 \
+			close((fd));	 \
 			errno = _e_;	 \
-			fd = -EBADF;	 \
+			(fd) = -EBADF;	 \
 		}			 \
 	} while (false)