diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2022-02-14 17:52:15 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-02-19 11:11:08 +0100 |
| commit | 8e12ab7c0e9f73ebfbcd6d37ece738f1825d58c8 (patch) | |
| tree | 4ac32cc3648e53b92f7732f2f11b69a826c2d3b1 | |
| parent | sched/preempt: Add PREEMPT_DYNAMIC using static keys (diff) | |
| download | linux-8e12ab7c0e9f73ebfbcd6d37ece738f1825d58c8.tar.xz linux-8e12ab7c0e9f73ebfbcd6d37ece738f1825d58c8.zip | |
arm64: entry: Centralize preemption decision
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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220214165216.2231574-7-mark.rutland@arm.com
| -rw-r--r-- | arch/arm64/kernel/entry-common.c | 20 |
1 files 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); } |