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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>
This commit is contained in:
Marc Zyngier 2019-04-08 16:49:06 +01:00 committed by Will Deacon
parent 57f27666f9
commit a862fc2254
2 changed files with 7 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/include/asm/arch_timer.h
View File

@ -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 {

25
drivers/clocksource/arm_arch_timer.c
View File

@ -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;
@ -582,16 +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",