Messages in this thread Patch in this message | | | From | Mark Rutland <> | Subject | [PATCH v2 6/7] arm64: entry: centralize premeption decision | Date | Fri, 4 Feb 2022 15:05:56 +0000 |
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For historical reasons, the decision of whether or not to preempt is spread across arm64_preempt_schedule_irq() and __el1_irq(), and it would be clearer if this were all in one place.
Also, arm64_preempt_schedule_irq() calls lockdep_assert_irqs_disabled(), but this is redundant, as we have a subsequent identical assertion in __exit_to_kernel_mode(), and preempt_schedule_irq() will BUG_ON(!irqs_disabled()) anyway.
This patch removes the redundant assertion and centralizes the preemption decision making within arm64_preempt_schedule_irq().
Other than the slight change to assertion behaviour, there should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Joey Gouly <joey.gouly@arm.com> Cc: Valentin Schneider <valentin.schneider@arm.com> Cc: Will Deacon <will@kernel.org> --- arch/arm64/kernel/entry-common.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index ef7fcefb96bd..2c639b6b676d 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -222,7 +222,16 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs) static void __sched arm64_preempt_schedule_irq(void) { - lockdep_assert_irqs_disabled(); + if (!IS_ENABLED(CONFIG_PREEMPTION)) + return; + + /* + * Note: thread_info::preempt_count includes both thread_info::count + * and thread_info::need_resched, and is not equivalent to + * preempt_count(). + */ + if (READ_ONCE(current_thread_info()->preempt_count) != 0) + return; /* * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC @@ -438,14 +447,7 @@ static __always_inline void __el1_irq(struct pt_regs *regs, do_interrupt_handler(regs, handler); irq_exit_rcu(); - /* - * Note: thread_info::preempt_count includes both thread_info::count - * and thread_info::need_resched, and is not equivalent to - * preempt_count(). - */ - if (IS_ENABLED(CONFIG_PREEMPTION) && - READ_ONCE(current_thread_info()->preempt_count) == 0) - arm64_preempt_schedule_irq(); + arm64_preempt_schedule_irq(); exit_to_kernel_mode(regs); } -- 2.30.2
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