NFC: Modified hci_transceive to become an asynchronous operation

This enables the completion callback to be called from a different
context, preventing a possible deadlock if the callback resulted in the
invocation of a nested call to the currently locked nfc_dev.
This is also more in line with the im_transceive nfc_ops for NFC Core or
NCI drivers which already behave asynchronously.

Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 42 insertions, 15 deletions

diff --git a/drivers/nfc/pn544_hci.c b/drivers/nfc/pn544_hci.c
index d90aecfce739..a176d1f7bbf3 100644
--- a/drivers/nfc/pn544_hci.c
+++ b/drivers/nfc/pn544_hci.c
@@ -148,6 +148,9 @@ struct pn544_hci_info {
                                  * < 0 if hardware error occured (e.g. i2c err)
                                  * and prevents normal operation.
                                  */
+        int async_cb_type;
+        data_exchange_cb_t async_cb;
+        void *async_cb_context;
 };
 
 static void pn544_hci_platform_init(struct pn544_hci_info *info)
@@ -731,6 +734,26 @@ static int pn544_hci_complete_target_discovered(struct nfc_shdlc *shdlc,
         return r;
 }
 
+#define PN544_CB_TYPE_READER_F 1
+
+static void pn544_hci_data_exchange_cb(void *context, struct sk_buff *skb,
+                                       int err)
+{
+        struct pn544_hci_info *info = context;
+
+        switch (info->async_cb_type) {
+        case PN544_CB_TYPE_READER_F:
+                if (err == 0)
+                        skb_pull(skb, 1);
+                info->async_cb(info->async_cb_context, skb, err);
+                break;
+        default:
+                if (err == 0)
+                        kfree_skb(skb);
+                break;
+        }
+}
+
 #define MIFARE_CMD_AUTH_KEY_A   0x60
 #define MIFARE_CMD_AUTH_KEY_B   0x61
 #define MIFARE_CMD_HEADER       2
@@ -744,11 +767,11 @@ static int pn544_hci_complete_target_discovered(struct nfc_shdlc *shdlc,
  */
 static int pn544_hci_data_exchange(struct nfc_shdlc *shdlc,
                                    struct nfc_target *target,
-                                   struct sk_buff *skb,
-                                   struct sk_buff **res_skb)
+                                   struct sk_buff *skb, data_exchange_cb_t cb,
+                                   void *cb_context)
 {
+        struct pn544_hci_info *info = nfc_shdlc_get_clientdata(shdlc);
         struct nfc_hci_dev *hdev = nfc_shdlc_get_hci_dev(shdlc);
-        int r;
 
         pr_info(DRIVER_DESC ": %s for gate=%d\n", __func__,
                 target->hci_reader_gate);
@@ -773,25 +796,29 @@ static int pn544_hci_data_exchange(struct nfc_shdlc *shdlc,
                                 memcpy(data, uid, MIFARE_UID_LEN);
                         }
 
-                        return nfc_hci_send_cmd(hdev, target->hci_reader_gate,
-                                                PN544_MIFARE_CMD,
-                                                skb->data, skb->len, res_skb);
+                        return nfc_hci_send_cmd_async(hdev,
+                                                      target->hci_reader_gate,
+                                                      PN544_MIFARE_CMD,
+                                                      skb->data, skb->len,
+                                                      cb, cb_context);
                 } else
                         return 1;
         case PN544_RF_READER_F_GATE:
                 *skb_push(skb, 1) = 0;
                 *skb_push(skb, 1) = 0;
 
-                r = nfc_hci_send_cmd(hdev, target->hci_reader_gate,
-                                     PN544_FELICA_RAW,
-                                     skb->data, skb->len, res_skb);
-                if (r == 0)
-                        skb_pull(*res_skb, 1);
-                return r;
+                info->async_cb_type = PN544_CB_TYPE_READER_F;
+                info->async_cb = cb;
+                info->async_cb_context = cb_context;
+
+                return nfc_hci_send_cmd_async(hdev, target->hci_reader_gate,
+                                              PN544_FELICA_RAW, skb->data,
+                                              skb->len,
+                                              pn544_hci_data_exchange_cb, info);
         case PN544_RF_READER_JEWEL_GATE:
-                return nfc_hci_send_cmd(hdev, target->hci_reader_gate,
-                                        PN544_JEWEL_RAW_CMD,
-                                        skb->data, skb->len, res_skb);
+                return nfc_hci_send_cmd_async(hdev, target->hci_reader_gate,
+                                              PN544_JEWEL_RAW_CMD, skb->data,
+                                              skb->len, cb, cb_context);
         default:
                 return 1;
         }