linux-kernel - [PATCH v2 1/1] hrtimers: Replace hrtimer_clock_to_base

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Message-ID: <20250214134424.3367619-1-andriy.shevchenko@linux.intel.com>
Date: Fri, 14 Feb 2025 15:43:33 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Frederic Weisbecker <frederic@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v2 1/1] hrtimers: Replace hrtimer_clock_to_base_table approach with switch-case

Clang (and GCC as well) complains about overlapped initialisers
in the hrtimer_clock_to_base_table definition. With `make W=1`
and CONFIG_WERROR=y (which is default nowadays) this breaks
the build:

  CC      kernel/time/hrtimer.o
kernel/time/hrtimer.c:124:21: error: initializer overrides prior initialization of this subobject [-Werror,-Winitializer-overrides]
  124 |         [CLOCK_REALTIME]        = HRTIMER_BASE_REALTIME,

kernel/time/hrtimer.c:122:27: note: previous initialization is here
  122 |         [0 ... MAX_CLOCKS - 1]  = HRTIMER_MAX_CLOCK_BASES,

(and similar for CLOCK_MONOTONIC, CLOCK_BOOTTIME, and CLOCK_TAI).

Replace hrtimer_clock_to_base_table approach with switch-case to make
the compiler happy.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---

v2: dropped 'rfc', rewrote to use switch-case (Thomas)

 kernel/time/hrtimer.c | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index deb1aa32814e..453dc76c9348 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -117,16 +117,6 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
 	.csd = CSD_INIT(retrigger_next_event, NULL)
 };
 
-static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
-	/* Make sure we catch unsupported clockids */
-	[0 ... MAX_CLOCKS - 1]	= HRTIMER_MAX_CLOCK_BASES,
-
-	[CLOCK_REALTIME]	= HRTIMER_BASE_REALTIME,
-	[CLOCK_MONOTONIC]	= HRTIMER_BASE_MONOTONIC,
-	[CLOCK_BOOTTIME]	= HRTIMER_BASE_BOOTTIME,
-	[CLOCK_TAI]		= HRTIMER_BASE_TAI,
-};
-
 static inline bool hrtimer_base_is_online(struct hrtimer_cpu_base *base)
 {
 	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
@@ -1587,14 +1577,19 @@ u64 hrtimer_next_event_without(const struct hrtimer *exclude)
 
 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
 {
-	if (likely(clock_id < MAX_CLOCKS)) {
-		int base = hrtimer_clock_to_base_table[clock_id];
-
-		if (likely(base != HRTIMER_MAX_CLOCK_BASES))
-			return base;
+	switch (clock_id) {
+	case CLOCK_REALTIME:
+		return HRTIMER_BASE_REALTIME;
+	case CLOCK_MONOTONIC:
+		return HRTIMER_BASE_MONOTONIC;
+	case CLOCK_BOOTTIME:
+		return HRTIMER_BASE_BOOTTIME;
+	case CLOCK_TAI:
+		return HRTIMER_BASE_TAI;
+	default:
+		WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
+		return HRTIMER_BASE_MONOTONIC;
 	}
-	WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
-	return HRTIMER_BASE_MONOTONIC;
 }
 
 static enum hrtimer_restart hrtimer_dummy_timeout(struct hrtimer *unused)
-- 
2.45.1.3035.g276e886db78b