selftests: timers: Fix valid-adjtimex signed left-shift undefined behavior

The struct adjtimex freq field takes a signed value who's units are in
shifted (<<16) parts-per-million.

Unfortunately for negative adjustments, the straightforward use of:

  freq = ppm << 16 trips undefined behavior warnings with clang:

valid-adjtimex.c:66:6: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
        -499<<16,
        ~~~~^
valid-adjtimex.c:67:6: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
        -450<<16,
        ~~~~^
..

Fix it by using a multiply by (1 << 16) instead of shifting negative values
in the valid-adjtimex test case. Align the values for better readability.

Reported-by: Lee Jones <joneslee@google.com>
Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/r/20240409202222.2830476-1-jstultz@google.com
Link: https://lore.kernel.org/lkml/0c6d4f0d-2064-4444-986b-1d1ed782135f@collabora.com/

diff --git a/tools/testing/selftests/timers/valid-adjtimex.c b/tools/testing/selftests/timers/valid-adjtimex.c
index 48b9a803235a80413f0d94d9eb841d9f045779e8..d13ebde203221ae3fa81835fae684c8e180cf111 100644 (file)
--- a/tools/testing/selftests/timers/valid-adjtimex.c
+++ b/tools/testing/selftests/timers/valid-adjtimex.c
@@ -21,9 +21,6 @@
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *   GNU General Public License for more details.
  */
-
-
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
@@ -62,45 +59,47 @@ int clear_time_state(void)
 #define NUM_FREQ_OUTOFRANGE 4
 #define NUM_FREQ_INVALID 2
 
+#define SHIFTED_PPM (1 << 16)
+
 long valid_freq[NUM_FREQ_VALID] = {
-       -499<<16,
-       -450<<16,
-       -400<<16,
-       -350<<16,
-       -300<<16,
-       -250<<16,
-       -200<<16,
-       -150<<16,
-       -100<<16,
-       -75<<16,
-       -50<<16,
-       -25<<16,
-       -10<<16,
-       -5<<16,
-       -1<<16,
+        -499 * SHIFTED_PPM,
+        -450 * SHIFTED_PPM,
+        -400 * SHIFTED_PPM,
+        -350 * SHIFTED_PPM,
+        -300 * SHIFTED_PPM,
+        -250 * SHIFTED_PPM,
+        -200 * SHIFTED_PPM,
+        -150 * SHIFTED_PPM,
+        -100 * SHIFTED_PPM,
+         -75 * SHIFTED_PPM,
+         -50 * SHIFTED_PPM,
+         -25 * SHIFTED_PPM,
+         -10 * SHIFTED_PPM,
+          -5 * SHIFTED_PPM,
+          -1 * SHIFTED_PPM,
        -1000,
-       1<<16,
-       5<<16,
-       10<<16,
-       25<<16,
-       50<<16,
-       75<<16,
-       100<<16,
-       150<<16,
-       200<<16,
-       250<<16,
-       300<<16,
-       350<<16,
-       400<<16,
-       450<<16,
-       499<<16,
+           1 * SHIFTED_PPM,
+           5 * SHIFTED_PPM,
+          10 * SHIFTED_PPM,
+          25 * SHIFTED_PPM,
+          50 * SHIFTED_PPM,
+          75 * SHIFTED_PPM,
+         100 * SHIFTED_PPM,
+         150 * SHIFTED_PPM,
+         200 * SHIFTED_PPM,
+         250 * SHIFTED_PPM,
+         300 * SHIFTED_PPM,
+         350 * SHIFTED_PPM,
+         400 * SHIFTED_PPM,
+         450 * SHIFTED_PPM,
+         499 * SHIFTED_PPM,
 };
 
 long outofrange_freq[NUM_FREQ_OUTOFRANGE] = {
-       -1000<<16,
-       -550<<16,
-       550<<16,
-       1000<<16,
+       -1000 * SHIFTED_PPM,
+        -550 * SHIFTED_PPM,
+         550 * SHIFTED_PPM,
+        1000 * SHIFTED_PPM,
 };
 
 #define LONG_MAX (~0UL>>1)