[PATCH 1/1] rapidio/rio_cm: avoid GFP_KERNEL in atomic context

[Alexandre Bounine]

As reported by Alexey Khoroshilov <khoroshi...@ispras.ru>
(see https://lkml.org/lkml/2016/9/9/737):
riocm_send_close() is called from rio_cm_shutdown() under
spin_lock_bh(idr_lock), but riocm_send_close() uses a GFP_KERNEL
allocation.

Fix by taking riocm_send_close() outside of spinlock protected code.

Reported-by: Alexey Khoroshilov <khoroshi...@ispras.ru>
Cc: Alexey Khoroshilov <khoroshi...@ispras.ru>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Alexandre Bounine <alexandre.boun...@idt.com>
---
 drivers/rapidio/rio_cm.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/rapidio/rio_cm.c b/drivers/rapidio/rio_cm.c
index 3226983..0e91335 100644
--- a/drivers/rapidio/rio_cm.c
+++ b/drivers/rapidio/rio_cm.c
@@ -2242,17 +2242,31 @@ static int rio_cm_shutdown(struct notifier_block *nb, 
unsigned long code,
 {
        struct rio_channel *ch;
        unsigned int i;
+       LIST_HEAD(list);
 
        riocm_debug(EXIT, ".");
 
+       /*
+        * If there are any channels left in connected state send
+        * close notification to the connection partner.
+        * First build a list of channels that require a closing
+        * notification because function riocm_send_close() should
+        * be called outside of spinlock protected code.
+        */
        spin_lock_bh(&idr_lock);
        idr_for_each_entry(&ch_idr, ch, i) {
-               riocm_debug(EXIT, "close ch %d", ch->id);
-               if (ch->state == RIO_CM_CONNECTED)
-                       riocm_send_close(ch);
+               if (ch->state == RIO_CM_CONNECTED) {
+                       riocm_debug(EXIT, "close ch %d", ch->id);
+                       idr_remove(&ch_idr, ch->id);
+                       list_add(&ch->ch_node, &list);
+               }
        }
        spin_unlock_bh(&idr_lock);
 
+       if (!list_empty(&list))
+               list_for_each_entry(ch, &list, ch_node)
+                       riocm_send_close(ch);
+
        return NOTIFY_DONE;
 }
 
-- 
2.9.0