[MIPS] SMTC: Fix recursion in instant IPI replay code.

local_irq_restore -> raw_local_irq_restore -> irq_restore_epilog ->
	smtc_ipi_replay -> smtc_ipi_dq -> spin_unlock_irqrestore ->
	_spin_unlock_irqrestore -> local_irq_restore

The recursion does abort when there is no more IPI queued for a CPU, so
this isn't usually fatal which is why we got away with this for so long
until this was discovered by code inspection.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 13 insertions, 3 deletions

diff --git a/include/asm-mips/smtc_ipi.h b/include/asm-mips/smtc_ipi.h
index 360ea6d250c7..a52a4a7a36e0 100644
--- a/include/asm-mips/smtc_ipi.h
+++ b/include/asm-mips/smtc_ipi.h
@@ -65,12 +65,10 @@ static inline void smtc_ipi_nq(struct smtc_ipi_q *q, struct smtc_ipi *p)
         spin_unlock_irqrestore(&q->lock, flags);
 }
 
-static inline struct smtc_ipi *smtc_ipi_dq(struct smtc_ipi_q *q)
+static inline struct smtc_ipi *__smtc_ipi_dq(struct smtc_ipi_q *q)
 {
         struct smtc_ipi *p;
-        long flags;
 
-        spin_lock_irqsave(&q->lock, flags);
         if (q->head == NULL)
                 p = NULL;
         else {
@@ -81,7 +79,19 @@ static inline struct smtc_ipi *smtc_ipi_dq(struct smtc_ipi_q *q)
                 if (q->head == NULL)
                         q->tail = NULL;
         }
+
+        return p;
+}
+
+static inline struct smtc_ipi *smtc_ipi_dq(struct smtc_ipi_q *q)
+{
+        unsigned long flags;
+        struct smtc_ipi *p;
+
+        spin_lock_irqsave(&q->lock, flags);
+        p = __smtc_ipi_dq(q);
         spin_unlock_irqrestore(&q->lock, flags);
+
         return p;
 }