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Commit a862fc22 authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

clocksource/arm_arch_timer: Remove use of workaround static key 



The use of a static key in a hotplug path has proved to be a real
nightmare, and makes it impossible to have scream-free lockdep
kernel.

Let's remove the static key altogether, and focus on something saner.

Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 57f27666

arch/arm64/include/asm/arch_timer.h

+0 −4
Original line number Diff line number Diff line
@@ -45,13 +45,9 @@ 
		(__wa && __wa->h) ? __wa->h : arch_timer_##h;		\

	})



extern struct static_key_false arch_timer_read_ool_enabled;

#define needs_unstable_timer_counter_workaround() \

	static_branch_unlikely(&arch_timer_read_ool_enabled)

#else

#define has_erratum_handler(h)			   false

#define erratum_handler(h)			   (arch_timer_##h)

#define needs_unstable_timer_counter_workaround()  false

#endif



enum arch_timer_erratum_match_type {

drivers/clocksource/arm_arch_timer.c

+7 −18
Original line number Diff line number Diff line
@@ -365,8 +365,6 @@ static u32 notrace sun50i_a64_read_cntv_tval_el0(void) 
DEFINE_PER_CPU(const struct arch_timer_erratum_workaround *, timer_unstable_counter_workaround);

EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);



DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled);

EXPORT_SYMBOL_GPL(arch_timer_read_ool_enabled);



static void erratum_set_next_event_tval_generic(const int access, unsigned long evt,

						struct clock_event_device *clk)
@@ -537,12 +535,6 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa 
			per_cpu(timer_unstable_counter_workaround, i) = wa;

	}



	/*

	 * Use the locked version, as we're called from the CPU

	 * hotplug framework. Otherwise, we end-up in deadlock-land.

	 */

	static_branch_enable_cpuslocked(&arch_timer_read_ool_enabled);



	/*

	 * Don't use the vdso fastpath if errata require using the

	 * out-of-line counter accessor. We may change our mind pretty
@@ -558,7 +550,7 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa 
static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type type,

					    void *arg)

{

	const struct arch_timer_erratum_workaround *wa;

	const struct arch_timer_erratum_workaround *wa, *__wa;

	ate_match_fn_t match_fn = NULL;

	bool local = false;
@@ -582,8 +574,6 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t 
	if (!wa)

		return;



	if (needs_unstable_timer_counter_workaround()) {

		const struct arch_timer_erratum_workaround *__wa;

	__wa = __this_cpu_read(timer_unstable_counter_workaround);

	if (__wa && wa != __wa)

		pr_warn("Can't enable workaround for %s (clashes with %s\n)",
@@ -591,7 +581,6 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t 


	if (__wa)

		return;

	}



	arch_timer_enable_workaround(wa, local);

	pr_info("Enabling %s workaround for %s\n",