firewire: Implement proper transaction cancelation.

Drivers such as fw-sbp2 had no way to properly cancel in-progress
transactions, which could leave a pending transaction or an unset
packet in the low-level queues after kfree'ing the containing
structure. fw_cancel_transaction() lets drivers cancel a submitted
transaction.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 47 insertions, 7 deletions

diff --git a/drivers/firewire/fw-transaction.c b/drivers/firewire/fw-transaction.c
index fb3b77e1bb2d..5394569a1c89 100644
--- a/drivers/firewire/fw-transaction.c
+++ b/drivers/firewire/fw-transaction.c
@@ -59,20 +59,52 @@
 #define phy_config_root_id(node_id)     ((((node_id) & 0x3f) << 24) | (1 << 23))
 #define phy_identifier(id)              ((id) << 30)
 
-static void
-close_transaction(struct fw_transaction *t, struct fw_card *card, int rcode,
-                  u32 * payload, size_t length)
+static int
+close_transaction(struct fw_transaction *transaction,
+                  struct fw_card *card, int rcode,
+                  u32 *payload, size_t length)
 {
+        struct fw_transaction *t;
         unsigned long flags;
 
         spin_lock_irqsave(&card->lock, flags);
-        card->tlabel_mask &= ~(1 << t->tlabel);
-        list_del(&t->link);
+        list_for_each_entry(t, &card->transaction_list, link) {
+                if (t == transaction) {
+                        list_del(&t->link);
+                        card->tlabel_mask &= ~(1 << t->tlabel);
+                        break;
+                }
+        }
         spin_unlock_irqrestore(&card->lock, flags);
 
-        t->callback(card, rcode, payload, length, t->callback_data);
+        if (&t->link != &card->transaction_list) {
+                t->callback(card, rcode, payload, length, t->callback_data);
+                return 0;
+        }
+
+        return -ENOENT;
 }
 
+/* Only valid for transactions that are potentially pending (ie have
+ * been sent). */
+int
+fw_cancel_transaction(struct fw_card *card,
+                      struct fw_transaction *transaction)
+{
+        /* Cancel the packet transmission if it's still queued.  That
+         * will call the packet transmission callback which cancels
+         * the transaction. */
+
+        if (card->driver->cancel_packet(card, &transaction->packet) == 0)
+                return 0;
+
+        /* If the request packet has already been sent, we need to see
+         * if the transaction is still pending and remove it in that case. */
+
+        return close_transaction(transaction, card, RCODE_CANCELLED, NULL, 0);
+}
+EXPORT_SYMBOL(fw_cancel_transaction);
+
 static void
 transmit_complete_callback(struct fw_packet *packet,
                            struct fw_card *card, int status)
@@ -162,6 +194,7 @@ fw_fill_request(struct fw_packet *packet, int tcode, int tlabel,
 
         packet->speed = speed;
         packet->generation = generation;
+        packet->ack = 0;
 }
 
 /**
@@ -298,8 +331,14 @@ void fw_flush_transactions(struct fw_card *card)
         card->tlabel_mask = 0;
         spin_unlock_irqrestore(&card->lock, flags);
 
-        list_for_each_entry_safe(t, next, &list, link)
+        list_for_each_entry_safe(t, next, &list, link) {
+                card->driver->cancel_packet(card, &t->packet);
+
+                /* At this point cancel_packet will never call the
+                 * transaction callback, since we just took all the
+                 * transactions out of the list.  So do it here.*/
                 t->callback(card, RCODE_CANCELLED, NULL, 0, t->callback_data);
+        }
 }
 
 static struct fw_address_handler *
@@ -531,6 +570,7 @@ allocate_request(struct fw_packet *p)
         request->response.speed = p->speed;
         request->response.timestamp = t;
         request->response.generation = p->generation;
+        request->response.ack = 0;
         request->response.callback = free_response_callback;
         request->ack = p->ack;
         request->length = length;