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sched/preempt: Simplify irqentry_exit_cond_resched() callers 

Currently callers of irqentry_exit_cond_resched() need to be aware of
whether the function should be indirected via a static call, leading to
ugly ifdeffery in callers.

Save them the hassle with a static inline wrapper that does the right
thing. The raw_irqentry_exit_cond_resched() will also be useful in
subsequent patches which will add conditional wrappers for preemption
functions.

Note: in arch/x86/entry/common.c, xen_pv_evtchn_do_upcall() always calls
irqentry_exit_cond_resched() directly, even when PREEMPT_DYNAMIC is in
use. I believe this is a latent bug (which this patch corrects), but I'm
not entirely certain this wasn't deliberate.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220214165216.2231574-4-mark.rutland@arm.com
This commit is contained in:
Mark Rutland 2022-02-14 16:52:12 +00:00 committed by Peter Zijlstra
parent 8a69fe0be1
commit 4624a14f4d
2 changed files with 10 additions and 11 deletions
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9
include/linux/entry-common.h
View File

@ -454,11 +454,14 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
*
* Conditional reschedule with additional sanity checks.
*/
void irqentry_exit_cond_resched(void);
void raw_irqentry_exit_cond_resched(void);
#ifdef CONFIG_PREEMPT_DYNAMIC
#define irqentry_exit_cond_resched_dynamic_enabled irqentry_exit_cond_resched
#define irqentry_exit_cond_resched_dynamic_enabled raw_irqentry_exit_cond_resched
#define irqentry_exit_cond_resched_dynamic_disabled NULL
DECLARE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
#define irqentry_exit_cond_resched() static_call(irqentry_exit_cond_resched)()
#else
#define irqentry_exit_cond_resched() raw_irqentry_exit_cond_resched()
#endif
/**

12
kernel/entry/common.c
View File

@ -380,7 +380,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
return ret;
}
void irqentry_exit_cond_resched(void)
void raw_irqentry_exit_cond_resched(void)
{
if (!preempt_count()) {
/* Sanity check RCU and thread stack */
@ -392,7 +392,7 @@ void irqentry_exit_cond_resched(void)
}
}
#ifdef CONFIG_PREEMPT_DYNAMIC
DEFINE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
DEFINE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
#endif
noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
@ -420,13 +420,9 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
}
instrumentation_begin();
if (IS_ENABLED(CONFIG_PREEMPTION)) {
#ifdef CONFIG_PREEMPT_DYNAMIC
static_call(irqentry_exit_cond_resched)();
#else
if (IS_ENABLED(CONFIG_PREEMPTION))
irqentry_exit_cond_resched();
#endif
}
/* Covers both tracing and lockdep */
trace_hardirqs_on();
instrumentation_end();