Commit f3e8fb55 authored by Eric Lapuyade's avatar Eric Lapuyade Committed by Samuel Ortiz
Browse files

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: default avatarEric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: default avatarSamuel Ortiz <sameo@linux.intel.com>
parent e4c4789e

drivers/nfc/pn544_hci.c

+42 −15
Original line number Diff line number Diff line
@@ -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,

			return nfc_hci_send_cmd_async(hdev,

						      target->hci_reader_gate,

						      PN544_MIFARE_CMD,

						skb->data, skb->len, res_skb);

						      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;

	}

include/net/nfc/hci.h

+6 −2
Original line number Diff line number Diff line
@@ -38,8 +38,8 @@ struct nfc_hci_ops { 
	int (*complete_target_discovered) (struct nfc_hci_dev *hdev, u8 gate,

					   struct nfc_target *target);

	int (*data_exchange) (struct nfc_hci_dev *hdev,

			      struct nfc_target *target,

			      struct sk_buff *skb, struct sk_buff **res_skb);

			      struct nfc_target *target, struct sk_buff *skb,

			      data_exchange_cb_t cb, void *cb_context);

	int (*check_presence)(struct nfc_hci_dev *hdev,

			      struct nfc_target *target);

};
@@ -103,6 +103,10 @@ struct nfc_hci_dev { 
	u8 hw_mpw;

	u8 hw_software;

	u8 hw_bsid;



	int async_cb_type;

	data_exchange_cb_t async_cb;

	void *async_cb_context;

};



/* hci device allocation */

include/net/nfc/shdlc.h

+2 −2
Original line number Diff line number Diff line
@@ -34,8 +34,8 @@ struct nfc_shdlc_ops { 
	int (*complete_target_discovered) (struct nfc_shdlc *shdlc, u8 gate,

					   struct nfc_target *target);

	int (*data_exchange) (struct nfc_shdlc *shdlc,

			      struct nfc_target *target,

			      struct sk_buff *skb, struct sk_buff **res_skb);

			      struct nfc_target *target, struct sk_buff *skb,

			      data_exchange_cb_t cb, void *cb_context);

	int (*check_presence)(struct nfc_shdlc *shdlc,

			      struct nfc_target *target);

};

net/nfc/hci/core.c

+39 −18
Original line number Diff line number Diff line
@@ -537,13 +537,37 @@ static void hci_deactivate_target(struct nfc_dev *nfc_dev, 
{

}



#define HCI_CB_TYPE_TRANSCEIVE 1



static void hci_transceive_cb(void *context, struct sk_buff *skb, int err)

{

	struct nfc_hci_dev *hdev = context;



	switch (hdev->async_cb_type) {

	case HCI_CB_TYPE_TRANSCEIVE:

		/*

		 * TODO: Check RF Error indicator to make sure data is valid.

		 * It seems that HCI cmd can complete without error, but data

		 * can be invalid if an RF error occured? Ignore for now.

		 */

		if (err == 0)

			skb_trim(skb, skb->len - 1); /* RF Err ind */



		hdev->async_cb(hdev->async_cb_context, skb, err);

		break;

	default:

		if (err == 0)

			kfree_skb(skb);

		break;

	}

}



static int hci_transceive(struct nfc_dev *nfc_dev, struct nfc_target *target,

			  struct sk_buff *skb, data_exchange_cb_t cb,

			  void *cb_context)

{

	struct nfc_hci_dev *hdev = nfc_get_drvdata(nfc_dev);

	int r;

	struct sk_buff *res_skb = NULL;



	pr_debug("target_idx=%d\n", target->idx);
@@ -551,40 +575,37 @@ static int hci_transceive(struct nfc_dev *nfc_dev, struct nfc_target *target, 
	case NFC_HCI_RF_READER_A_GATE:

	case NFC_HCI_RF_READER_B_GATE:

		if (hdev->ops->data_exchange) {

			r = hdev->ops->data_exchange(hdev, target, skb,

						     &res_skb);

			r = hdev->ops->data_exchange(hdev, target, skb, cb,

						     cb_context);

			if (r <= 0)	/* handled */

				break;

		}



		*skb_push(skb, 1) = 0;	/* CTR, see spec:10.2.2.1 */

		r = nfc_hci_send_cmd(hdev, target->hci_reader_gate,

				     NFC_HCI_WR_XCHG_DATA,

				     skb->data, skb->len, &res_skb);

		/*

		 * TODO: Check RF Error indicator to make sure data is valid.

		 * It seems that HCI cmd can complete without error, but data

		 * can be invalid if an RF error occured? Ignore for now.

		 */

		if (r == 0)

			skb_trim(res_skb, res_skb->len - 1); /* RF Err ind */



		hdev->async_cb_type = HCI_CB_TYPE_TRANSCEIVE;

		hdev->async_cb = cb;

		hdev->async_cb_context = cb_context;



		r = nfc_hci_send_cmd_async(hdev, target->hci_reader_gate,

					   NFC_HCI_WR_XCHG_DATA, skb->data,

					   skb->len, hci_transceive_cb, hdev);

		break;

	default:

		if (hdev->ops->data_exchange) {

			r = hdev->ops->data_exchange(hdev, target, skb,

						     &res_skb);

			r = hdev->ops->data_exchange(hdev, target, skb, cb,

						     cb_context);

			if (r == 1)

				r = -ENOTSUPP;

		}

		else

			r = -ENOTSUPP;

		break;

	}



	kfree_skb(skb);



	cb(cb_context, res_skb, r);



	return 0;

	return r;

}



static int hci_check_presence(struct nfc_dev *nfc_dev,

net/nfc/hci/shdlc.c

+3 −2
Original line number Diff line number Diff line
@@ -777,12 +777,13 @@ static int nfc_shdlc_complete_target_discovered(struct nfc_hci_dev *hdev, 
static int nfc_shdlc_data_exchange(struct nfc_hci_dev *hdev,

				   struct nfc_target *target,

				   struct sk_buff *skb,

				   struct sk_buff **res_skb)

				   data_exchange_cb_t cb, void *cb_context)

{

	struct nfc_shdlc *shdlc = nfc_hci_get_clientdata(hdev);



	if (shdlc->ops->data_exchange)

		return shdlc->ops->data_exchange(shdlc, target, skb, res_skb);

		return shdlc->ops->data_exchange(shdlc, target, skb, cb,

						 cb_context);



	return -EPERM;

}