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authorMarc Zyngier <marc.zyngier@arm.com>2019-04-08 16:49:06 +0100
committerWill Deacon <will.deacon@arm.com>2019-04-30 16:11:47 +0100
commita862fc2254bdbcee3b5da4f730984e5d8393a2f1 (patch)
tree2ffc91823d98d9631237995c9ef7866de5eb0edb
parent57f27666f91a85431492b092f5db53ecab1a0739 (diff)
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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: Mark Rutland <mark.rutland@arm.com> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
-rw-r--r--arch/arm64/include/asm/arch_timer.h4
-rw-r--r--drivers/clocksource/arm_arch_timer.c25
2 files changed, 7 insertions, 22 deletions
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 4a06d46def7e..5502ea049b63 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -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 {
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index b2a88a64aab4..8f22976247c0 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -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)
@@ -538,12 +536,6 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *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
* late in the game (with a per-CPU erratum, for example), so
@@ -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;
@@ -582,16 +574,13 @@ 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)",
- wa->desc, __wa->desc);
+ __wa = __this_cpu_read(timer_unstable_counter_workaround);
+ if (__wa && wa != __wa)
+ pr_warn("Can't enable workaround for %s (clashes with %s\n)",
+ wa->desc, __wa->desc);
- if (__wa)
- return;
- }
+ if (__wa)
+ return;
arch_timer_enable_workaround(wa, local);
pr_info("Enabling %s workaround for %s\n",