Char: cyclades, allow DEBUG_SHIRQ

Test if base addr is non-null in ISR to prove the card has been correctly
initialized.  This is needed for DEBUG_SHIRQ for example.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/char/cyclades.c b/drivers/char/cyclades.c
index 353e888295d1..9d22d58f4298 100644
--- a/drivers/char/cyclades.c
+++ b/drivers/char/cyclades.c
@@ -1444,6 +1444,10 @@ static irqreturn_t cyy_interrupt(int irq, void *dev_id)
         card_base_addr = cinfo->base_addr;
         index = cinfo->bus_index;
 
+        /* card was not initialized yet (e.g. DEBUG_SHIRQ) */
+        if (unlikely(card_base_addr == NULL))
+                return IRQ_HANDLED;
+
         /* This loop checks all chips in the card.  Make a note whenever
            _any_ chip had some work to do, as this is considered an
            indication that there will be more to do.  Only when no chip