rapidio/rio_cm: avoid GFP_KERNEL in atomic context

As reported by Alexey Khoroshilov (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.

[akpm@linux-foundation.org: remove unneeded `if (!list_empty())']
Link: http://lkml.kernel.org/r/20160915175402.10122-1-alexandre.bounine@idt.com
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Reported-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/drivers/rapidio/rio_cm.c b/drivers/rapidio/rio_cm.c
index 3fa17ac8df54..cebc296463ad 100644
--- a/drivers/rapidio/rio_cm.c
+++ b/drivers/rapidio/rio_cm.c
@@ -2247,17 +2247,30 @@ 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);
 
+        list_for_each_entry(ch, &list, ch_node)
+                riocm_send_close(ch);
+
         return NOTIFY_DONE;
 }