diff options
author | Michael Thalmeier <michael.thalmeier@hale.at> | 2016-03-25 14:46:52 (GMT) |
---|---|---|
committer | Samuel Ortiz <sameo@linux.intel.com> | 2016-04-09 21:53:11 (GMT) |
commit | 37f895d7e85e7d7e23e2395e666ea43001862e5f (patch) | |
tree | dcd5eb04a148715be4a57bae469e2c12f1d6862a /drivers/nfc/pn533.c | |
parent | e997ebbe46fe46bd4e8d476adca1f9b76779f270 (diff) | |
download | linux-37f895d7e85e7d7e23e2395e666ea43001862e5f.tar.xz |
NFC: pn533: Fix socket deadlock
A deadlock can occur when the NFC raw socket is closed while
the driver is processing a command.
Following is the call graph of the affected situation:
send data via raw_sock:
-------------
rawsock_tx_work
sock_hold => socket refcnt++
nfc_data_exchange => cb = rawsock_data_exchange_complete
ops->im_transceive = pn533_transceive => arg->cb = db
= rawsock_data_exchange_complete
pn533_send_data_async => cb = pn533_data_exchange_complete
__pn533_send_async => cmd->complete_cb = cb
= pn533_data_exchange_complete
if_ops->send_frame_async
response:
--------
pn533_recv_response
queue_work(priv->wq, &priv->cmd_complete_work)
pn533_wq_cmd_complete
pn533_send_async_complete
cmd->complete_cb() = pn533_data_exchange_complete()
arg->cb() = rawsock_data_exchange_complete()
sock_put => socket refcnt-- => If the corresponding
socket gets closed in the meantime socket
will be destructed
sk_free
__sk_free
sk->sk_destruct = rawsock_destruct
nfc_deactivate_target
ops->deactivate_target = pn533_deactivate_target
pn533_send_cmd_sync
pn533_send_cmd_async
__pn533_send_async
list_add_tail(&cmd->queue,&dev->cmd_queue)
=> add to command list because
a command is currently
processed
wait_for_completion
=> the workqueue thread waits
here because it is the one
processing the commands
=> deadlock
To fix the deadlock pn533_deactivate_target is changed to
issue the PN533_CMD_IN_RELEASE command in async mode. This
way nothing blocks and the release command is executed after
the current command.
Signed-off-by: Michael Thalmeier <michael.thalmeier@hale.at>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'drivers/nfc/pn533.c')
-rw-r--r-- | drivers/nfc/pn533.c | 40 |
1 files changed, 30 insertions, 10 deletions
diff --git a/drivers/nfc/pn533.c b/drivers/nfc/pn533.c index a85830f..074f1e4 100644 --- a/drivers/nfc/pn533.c +++ b/drivers/nfc/pn533.c @@ -2263,12 +2263,35 @@ static int pn533_activate_target(struct nfc_dev *nfc_dev, return 0; } +static int pn533_deactivate_target_complete(struct pn533 *dev, void *arg, + struct sk_buff *resp) +{ + int rc = 0; + + dev_dbg(&dev->interface->dev, "%s\n", __func__); + + if (IS_ERR(resp)) { + rc = PTR_ERR(resp); + + nfc_err(&dev->interface->dev, "Target release error %d\n", rc); + + return rc; + } + + rc = resp->data[0] & PN533_CMD_RET_MASK; + if (rc != PN533_CMD_RET_SUCCESS) + nfc_err(&dev->interface->dev, + "Error 0x%x when releasing the target\n", rc); + + dev_kfree_skb(resp); + return rc; +} + static void pn533_deactivate_target(struct nfc_dev *nfc_dev, struct nfc_target *target, u8 mode) { struct pn533 *dev = nfc_get_drvdata(nfc_dev); struct sk_buff *skb; - struct sk_buff *resp; int rc; dev_dbg(&dev->interface->dev, "%s\n", __func__); @@ -2287,16 +2310,13 @@ static void pn533_deactivate_target(struct nfc_dev *nfc_dev, *skb_put(skb, 1) = 1; /* TG*/ - resp = pn533_send_cmd_sync(dev, PN533_CMD_IN_RELEASE, skb); - if (IS_ERR(resp)) - return; - - rc = resp->data[0] & PN533_CMD_RET_MASK; - if (rc != PN533_CMD_RET_SUCCESS) - nfc_err(&dev->interface->dev, - "Error 0x%x when releasing the target\n", rc); + rc = pn533_send_cmd_async(dev, PN533_CMD_IN_RELEASE, skb, + pn533_deactivate_target_complete, NULL); + if (rc < 0) { + dev_kfree_skb(skb); + nfc_err(&dev->interface->dev, "Target release error %d\n", rc); + } - dev_kfree_skb(resp); return; } |