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NFC: Modified hci_transceive to become an asynchronous operation

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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>
This commit is contained in:
Eric Lapuyade 2012-09-11 10:43:50 +02:00 • committed by Samuel Ortiz
parent e4c4789e55
commit f3e8fb5527
5 changed files with 92 additions and 39 deletions
Download patch file Download diff file Expand all files Collapse all files

57
net/nfc/hci/core.c
View file

@ -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,

5
net/nfc/hci/shdlc.c
View file

@ -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;
}