Patchwork [v1,1/1] ppc64: max next_tb to prevent from replaying timer interrupt

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Submitter Tiejun Chen
Date Jan. 16, 2013, 3:01 a.m.
Message ID <1358305279-19068-1-git-send-email-tiejun.chen@windriver.com>
Download mbox | patch
Permalink /patch/212382/
State Accepted, archived
Commit 689dfa894c57842a05bf6dc9f97e6bb71ec5f386
Headers show

Comments

Tiejun Chen - Jan. 16, 2013, 3:01 a.m.
With lazy interrupt, we always call __check_irq_replaysome with
decrementers_next_tb to check if we need to replay timer interrupt.
So in hotplug case we also need to set decrementers_next_tb as MAX
to make sure __check_irq_replay don't replay timer interrupt
when return as we expect, otherwise we'll trap here infinitely.

Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
---
v1:

* In hotplug case we max decrementers_next_tb to prevent from
replaying timer interrupt for any offline CPU.

 arch/powerpc/kernel/time.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Patch

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 6f6b1cc..127361e 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -494,10 +494,15 @@  void timer_interrupt(struct pt_regs * regs)
 	set_dec(DECREMENTER_MAX);
 
 	/* Some implementations of hotplug will get timer interrupts while
-	 * offline, just ignore these
+	 * offline, just ignore these and we also need to set
+	 * decrementers_next_tb as MAX to make sure __check_irq_replay
+	 * don't replay timer interrupt when return, otherwise we'll trap
+	 * here infinitely :(
 	 */
-	if (!cpu_online(smp_processor_id()))
+	if (!cpu_online(smp_processor_id())) {
+		*next_tb = ~(u64)0;
 		return;
+	}
 
 	/* Conditionally hard-enable interrupts now that the DEC has been
 	 * bumped to its maximum value