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authorJames Hogan <james.hogan@imgtec.com>2013-07-01 13:44:10 +0100
committerJames Hogan <james.hogan@imgtec.com>2013-07-02 14:12:08 +0100
commitf6b30d32d242243a967993789c4cf550d840727e (patch)
tree95369d42eb77261e5f31b7908ee97af9e2f6a73e /arch/metag
parent9649814432faa9016952895684120942da0d8481 (diff)
downloadlinux-linaro-stable-f6b30d32d242243a967993789c4cf550d840727e.tar.gz
metag: kick: add missing irq_enter/exit to kick_handler()
kick_handler() doesn't have an irq_enter/exit pair, but it's used for handling SMP IPIs which require work to be done in softirqs, which are invoked from irq_exit() when the hard irq nest count reaches 0. The scheduler_ipi() callback in the IPI handler calls irq_enter/exit itself, but this is inside kick_handler()'s spin lock critical section, so if an invoked softirq issues an IPI the kick_handler() will be re-entered on the same CPU and will deadlock. This is easily fixed by adding the missing irq_enter/exit to kick_handler() so that the hard irq nest count doesn't reach 0 until after the spin lock has been released. Ideally the spin lock protected handler list will also be replaced by a lockless RCU protected list since it is certainly mostly read. That can be done in a later change though. Signed-off-by: James Hogan <james.hogan@imgtec.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/metag')
-rw-r--r--arch/metag/kernel/kick.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/metag/kernel/kick.c b/arch/metag/kernel/kick.c
index 50fcbec98cd2..beb377621322 100644
--- a/arch/metag/kernel/kick.c
+++ b/arch/metag/kernel/kick.c
@@ -26,6 +26,8 @@
* pass it as an argument.
*/
#include <linux/export.h>
+#include <linux/hardirq.h>
+#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/types.h>
@@ -66,6 +68,7 @@ EXPORT_SYMBOL(kick_unregister_func);
TBIRES
kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
{
+ struct pt_regs *old_regs;
struct kick_irq_handler *kh;
struct list_head *lh;
int handled = 0;
@@ -79,6 +82,9 @@ kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
trace_hardirqs_off();
+ old_regs = set_irq_regs((struct pt_regs *)State.Sig.pCtx);
+ irq_enter();
+
/*
* There is no need to disable interrupts here because we
* can't nest KICK interrupts in a KICK interrupt handler.
@@ -97,5 +103,8 @@ kick_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
WARN_ON(!handled);
+ irq_exit();
+ set_irq_regs(old_regs);
+
return tail_end(ret);
}