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Commit 482333b2 authored by Thierry Escande's avatar Thierry Escande Committed by Samuel Ortiz
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NFC: digital: Fix ACK & NACK PDUs handling in target mode 



When the target receives a NACK PDU, it re-sends the last sent PDU.

ACK PDUs are received by the target as a reply from the initiator to
chained I-PDUs. There are 3 cases to handle:
- If the target has previously received 1 or more ATN PDUs and the PNI
  in the ACK PDU is equal to the target PNI - 1, then it means that the
  initiator did not received the last issued PDU from the target. In
  this case it re-sends this PDU.
- If the target has received 1 or more ATN PDUs but the ACK PNI is not
  the target PNI - 1, then this means that this ACK is the reply of the
  previous chained I-PDU sent by the target. The target did not received
  it on the first attempt and it is being re-sent by the initiator. The
  process continues as usual.
- No ATN PDU received before this ACK PDU. This is the reply of a
  chained I-PDU. The target keeps on processing its chained I-PDU.

The code has been refactored to avoid too many indentation levels.

Also, ACK and NACK PDUs were not freed. This is now fixed.

Signed-off-by: default avatarThierry Escande <thierry.escande@collabora.com>
Signed-off-by: default avatarSamuel Ortiz <sameo@linux.intel.com>
parent f23a9868

net/nfc/digital_dep.c

+43 −28
Original line number Diff line number Diff line
@@ -1141,49 +1141,64 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg, 
		rc = 0;

		break;

	case DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU:

		if (!DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) { /* ACK */

			if ((ddev->atn_count &&

			     (DIGITAL_NFC_DEP_PFB_PNI(pfb - 1) !=

						ddev->curr_nfc_dep_pni)) ||

			    (DIGITAL_NFC_DEP_PFB_PNI(pfb) !=

						ddev->curr_nfc_dep_pni) ||

			    !ddev->chaining_skb || !ddev->saved_skb) {

		if (DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) { /* NACK */

			if (DIGITAL_NFC_DEP_PFB_PNI(pfb + 1) !=

						ddev->curr_nfc_dep_pni) {

				rc = -EIO;

				goto exit;

			}



			if (ddev->atn_count) {

			ddev->atn_count = 0;



			rc = digital_tg_send_saved_skb(ddev);

			if (rc)

				goto exit;



				return;

			goto free_resp;

		}



			kfree_skb(ddev->saved_skb);

			ddev->saved_skb = NULL;

		/* ACK */

		if (ddev->atn_count) {

			/* The target has previously recevied one or more ATN

			 * PDUs.

			 */

			ddev->atn_count = 0;



			rc = digital_tg_send_dep_res(ddev, ddev->chaining_skb);

			/* If the ACK PNI is equal to the target PNI - 1 means

			 * that the initiator did not receive the previous PDU

			 * sent by the target so re-send it.

			 */

			if (DIGITAL_NFC_DEP_PFB_PNI(pfb + 1) ==

						ddev->curr_nfc_dep_pni) {

				rc = digital_tg_send_saved_skb(ddev);

				if (rc)

					goto exit;

		} else { /* NACK */

			if ((DIGITAL_NFC_DEP_PFB_PNI(pfb + 1) !=

						ddev->curr_nfc_dep_pni) ||

			    !ddev->saved_skb) {



				goto free_resp;

			}



			/* Otherwise, the target did not receive the previous

			 * ACK PDU from the initiator. Fallback to normal

			 * processing of chained PDU then.

			 */

		}



		/* Keep on sending chained PDU */

		if (!ddev->chaining_skb ||

		    DIGITAL_NFC_DEP_PFB_PNI(pfb) !=

					ddev->curr_nfc_dep_pni) {

			rc = -EIO;

			goto exit;

		}



			ddev->atn_count = 0;

		kfree_skb(ddev->saved_skb);

		ddev->saved_skb = NULL;



			rc = digital_tg_send_saved_skb(ddev);

		rc = digital_tg_send_dep_res(ddev, ddev->chaining_skb);

		if (rc)

			goto exit;

		}



		return;

		goto free_resp;

	case DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU:

		if (DIGITAL_NFC_DEP_PFB_IS_TIMEOUT(pfb)) {

			rc = -EINVAL;