time/sched_clock: Disable interrupts in sched_clock_register()

Instead of issueing a warning if sched_clock_register() is called from a
context where IRQs are enabled, the code now ensures that IRQs are indeed
disabled.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200107010630.954648-1-paul@crapouillou.net

diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index dbd6905..e4332e3 100644 (file)
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -169,14 +169,15 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
 {
        u64 res, wrap, new_mask, new_epoch, cyc, ns;
        u32 new_mult, new_shift;
-       unsigned long r;
+       unsigned long r, flags;
        char r_unit;
        struct clock_read_data rd;
 
        if (cd.rate > rate)
                return;
 
-       WARN_ON(!irqs_disabled());
+       /* Cannot register a sched_clock with interrupts on */
+       local_irq_save(flags);
 
        /* Calculate the mult/shift to convert counter ticks to ns. */
        clocks_calc_mult_shift(&new_mult, &new_shift, rate, NSEC_PER_SEC, 3600);
@@ -233,6 +234,8 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
        if (irqtime > 0 || (irqtime == -1 && rate >= 1000000))
                enable_sched_clock_irqtime();
 
+       local_irq_restore(flags);
+
        pr_debug("Registered %pS as sched_clock source\n", read);
 }