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clock: Correct the usage of atomic64_t atomic functions

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Replace CONFIG_SYSTEM_TIME64 conditional atomic64 operations with a unified
seqlock-based approach for managing the system tick counter. This simplifies
code by eliminating architecture-specific branches and provides more robust
thread-safe access patterns.

Signed-off-by: hujun5 <hujun5@xiaomi.com>
This commit is contained in:
hujun5
2026-01-30 19:06:54 +08:00
committed by Xiang Xiao
parent 45f4e72d22
commit 29e514b276
2 changed files with 15 additions and 30 deletions
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4
arch/arm/include/armv8-m/barriers.h
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@@ -35,8 +35,8 @@
#define arm_isb() __asm__ __volatile__ ("isb " : : : "memory")
#define arm_dmb() __asm__ __volatile__ ("dmb " : : : "memory")
#define arm_rmb() __asm__ __volatile__ ("dmb ishld" : : : "memory")
#define arm_wmb() __asm__ __volatile__ ("dmb ishst" : : : "memory")
#define arm_rmb() __asm__ __volatile__ ("dmb " : : : "memory")
#define arm_wmb() __asm__ __volatile__ ("dmb " : : : "memory")
#define arm_dsb(n) __asm__ __volatile__ ("dsb " #n : : : "memory")
#define UP_ISB() arm_isb()

41
sched/clock/clock_sched_ticks.c
View File

@@ -31,6 +31,7 @@
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#include <nuttx/seqlock.h>
#include "clock/clock.h"
@@ -39,6 +40,7 @@
****************************************************************************/
static volatile clock_t g_system_ticks = INITIAL_SYSTEM_TIMER_TICKS;
static seqcount_t g_system_tick_lock = SEQLOCK_INITIALIZER;
/****************************************************************************
* Public Functions
@@ -62,13 +64,13 @@ static volatile clock_t g_system_ticks = INITIAL_SYSTEM_TIMER_TICKS;
void clock_increase_sched_ticks(clock_t ticks)
{
irqstate_t flags;
/* Increment the per-tick scheduler counter */
#ifdef CONFIG_SYSTEM_TIME64
atomic64_fetch_add((FAR atomic64_t *)&g_system_ticks, ticks);
#else
atomic_fetch_add((FAR atomic_t *)&g_system_ticks, ticks);
#endif
flags = write_seqlock_irqsave(&g_system_tick_lock);
g_system_ticks += ticks;
write_sequnlock_irqrestore(&g_system_tick_lock, flags);
}
/****************************************************************************
@@ -86,32 +88,15 @@ void clock_increase_sched_ticks(clock_t ticks)
clock_t clock_get_sched_ticks(void)
{
#ifdef CONFIG_SYSTEM_TIME64
clock_t sample;
clock_t verify;
/* 64-bit accesses are not atomic on most architectures. The following
* loop samples the 64-bit counter twice and retries in the rare case
* that a 32-bit rollover occurs between samples.
*
* If no 32-bit rollover occurs:
* - The MS 32 bits of both samples will be identical, and
* - The LS 32 bits of the second sample will be greater than or equal
* to those of the first.
*/
clock_t ret;
unsigned int seq;
do
{
verify = g_system_ticks;
sample = g_system_ticks;
seq = read_seqbegin(&g_system_tick_lock);
ret = g_system_ticks;
}
while ((sample & TIMER_MASK32) < (verify & TIMER_MASK32) ||
(sample & ~TIMER_MASK32) != (verify & ~TIMER_MASK32));
while (read_seqretry(&g_system_tick_lock, seq));
return sample;
#else
/* On 32-bit systems, atomic access is guaranteed */
return g_system_ticks;
#endif
return ret;
}