[tip: timers/core] time/sched_clock: Disable interrupts in sched_clock_register()

[tip-bot2 for Paul Cercueil]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     479c296303e8d29711a5153f0fc4b67faa6d9866
Gitweb:        https://git.kernel.org/tip/479c296303e8d29711a5153f0fc4b67faa6d9866
Author:        Paul Cercueil <paul@xxxxxxxxxxxxxxx>
AuthorDate:    Tue, 07 Jan 2020 02:06:29 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 09 Jan 2020 18:28:34 +01:00

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@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200107010630.954648-1-paul@xxxxxxxxxxxxxxx

---
 kernel/time/sched_clock.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index dbd6905..e4332e3 100644
--- 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);
 }