[PATCH v2] clocksource: Use GENMASK_ULL in definition of CLOCKSOURCE_MASK

[PATCH v2] clocksource: Use GENMASK_ULL in definition of CLOCKSOURCE_MASK

[Matthias Kaehlcke]

Besides reusing existing code this removes the special case handling
for 64-bit masks, which causes clang to raise a shift count overflow
warning due to https://bugs.llvm.org//show_bug.cgi?id=10030.

Suggested-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
Changes in v2:
- Remove unnecessary cast to u64

 include/linux/clocksource.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index cfc75848a35d..f2b10d9ebd04 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -120,7 +120,7 @@ struct clocksource {
 #define CLOCK_SOURCE_RESELECT			0x100
 
 /* simplify initialization of mask field */
-#define CLOCKSOURCE_MASK(bits) (u64)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
+#define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0)
 
 static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
 {
-- 
2.12.2.816.g2cccc81164-goog

[tip:timers/core] clocksource: Use GENMASK_ULL in definition of CLOCKSOURCE_MASK

[tip-bot for Matthias Kaehlcke]

Commit-ID:  0773cea37470f8e080c510fe720fc356cf35df3a
Gitweb:     http://git.kernel.org/tip/0773cea37470f8e080c510fe720fc356cf35df3a
Author:     Matthias Kaehlcke <mka@chromium.org>
AuthorDate: Tue, 18 Apr 2017 16:30:37 -0700
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 20 Apr 2017 14:56:58 +0200

clocksource: Use GENMASK_ULL in definition of CLOCKSOURCE_MASK

Besides reusing existing code this removes the special case handling
for 64-bit masks, which causes clang to raise a shift count overflow
warning due to https://bugs.llvm.org//show_bug.cgi?id=10030.

Suggested-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Grant Grundler <grundler@chromium.org>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Michael Davidson <md@google.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170418233037.70990-1-mka@chromium.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 include/linux/clocksource.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index cfc7584..f2b10d9 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -120,7 +120,7 @@ struct clocksource {
 #define CLOCK_SOURCE_RESELECT			0x100
 
 /* simplify initialization of mask field */
-#define CLOCKSOURCE_MASK(bits) (u64)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
+#define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0)
 
 static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
 {