From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: ardb@kernel.org, bp@alien8.de, catalin.marinas@arm.com,
dave.hansen@linux.intel.com, frederic@kernel.org,
james.morse@arm.com, joey.gouly@arm.com, juri.lelli@redhat.com,
linux-kernel@vger.kernel.org, luto@kernel.org,
mark.rutland@arm.com, mingo@redhat.com, peterz@infradead.org,
tglx@linutronix.de, valentin.schneider@arm.com, will@kernel.org
Subject: [PATCH v4 6/7] arm64: entry: centralize preemption decision
Date: Mon, 14 Feb 2022 16:52:15 +0000 [thread overview]
Message-ID: <20220214165216.2231574-7-mark.rutland@arm.com> (raw)
In-Reply-To: <20220214165216.2231574-1-mark.rutland@arm.com>
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>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: 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
next prev parent reply other threads:[~2022-02-14 16:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-14 16:52 [PATCH v4 0/7] arm64 / sched/preempt: support PREEMPT_DYNAMIC with static keys Mark Rutland
2022-02-14 16:52 ` [PATCH v4 1/7] sched/preempt: move PREEMPT_DYNAMIC logic later Mark Rutland
2022-02-19 10:21 ` [tip: sched/core] sched/preempt: Move " tip-bot2 for Mark Rutland
2022-02-14 16:52 ` [PATCH v4 2/7] sched/preempt: refactor sched_dynamic_update() Mark Rutland
2022-02-19 10:21 ` [tip: sched/core] sched/preempt: Refactor sched_dynamic_update() tip-bot2 for Mark Rutland
2022-02-14 16:52 ` [PATCH v4 3/7] sched/preempt: simplify irqentry_exit_cond_resched() callers Mark Rutland
2022-02-19 10:21 ` [tip: sched/core] sched/preempt: Simplify " tip-bot2 for Mark Rutland
2022-02-14 16:52 ` [PATCH v4 4/7] sched/preempt: decouple HAVE_PREEMPT_DYNAMIC from GENERIC_ENTRY Mark Rutland
2022-02-19 10:21 ` [tip: sched/core] sched/preempt: Decouple " tip-bot2 for Mark Rutland
2022-02-14 16:52 ` [PATCH v4 5/7] sched/preempt: add PREEMPT_DYNAMIC using static keys Mark Rutland
2022-02-19 10:21 ` [tip: sched/core] sched/preempt: Add " tip-bot2 for Mark Rutland
2022-03-18 8:49 ` [PATCH v4 5/7] sched/preempt: add " Sven Schnelle
2022-02-14 16:52 ` Mark Rutland [this message]
2022-02-19 10:21 ` [tip: sched/core] arm64: entry: Centralize preemption decision tip-bot2 for Mark Rutland
2022-02-14 16:52 ` [PATCH v4 7/7] arm64: support PREEMPT_DYNAMIC Mark Rutland
2022-02-19 10:21 ` [tip: sched/core] arm64: Support PREEMPT_DYNAMIC tip-bot2 for Mark Rutland
2022-02-17 13:52 ` [PATCH v4 0/7] arm64 / sched/preempt: support PREEMPT_DYNAMIC with static keys Frederic Weisbecker
2022-02-17 18:59 ` Peter Zijlstra
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