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preempt/dynamic: Provide irqentry_exit_cond_resched() static call 

Provide static call to control IRQ preemption (called in CONFIG_PREEMPT)
so that we can override its behaviour when preempt= is overriden.

Since the default behaviour is full preemption, its call is
initialized to provide IRQ preemption when preempt= isn't passed.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-8-frederic@kernel.org
This commit is contained in:
Peter Zijlstra (Intel) 2021-01-18 15:12:22 +01:00 committed by Ingo Molnar
parent 2c9a98d3bc
commit 40607ee97e
2 changed files with 13 additions and 1 deletions
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4
include/linux/entry-common.h
View File

@ -2,6 +2,7 @@
#ifndef __LINUX_ENTRYCOMMON_H
#define __LINUX_ENTRYCOMMON_H
#include <linux/static_call_types.h>
#include <linux/tracehook.h>
#include <linux/syscalls.h>
#include <linux/seccomp.h>
@ -454,6 +455,9 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
* Conditional reschedule with additional sanity checks.
*/
void irqentry_exit_cond_resched(void);
#ifdef CONFIG_PREEMPT_DYNAMIC
DECLARE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
#endif
/**
* irqentry_exit - Handle return from exception that used irqentry_enter()

10
kernel/entry/common.c
View File

@ -385,6 +385,9 @@ void irqentry_exit_cond_resched(void)
preempt_schedule_irq();
}
}
#ifdef CONFIG_PREEMPT_DYNAMIC
DEFINE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
#endif
noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
{
@ -411,8 +414,13 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
}
instrumentation_begin();
if (IS_ENABLED(CONFIG_PREEMPTION))
if (IS_ENABLED(CONFIG_PREEMPTION)) {
#ifdef CONFIG_PREEMT_DYNAMIC
static_call(irqentry_exit_cond_resched)();
#else
irqentry_exit_cond_resched();
#endif
}
/* Covers both tracing and lockdep */
trace_hardirqs_on();
instrumentation_end();