Lin Ma 86cdf8e387 NFC: reorganize the functions in nci_request
There is a possible data race as shown below:

thread-A in nci_request()       | thread-B in nci_close_device()
                                | mutex_lock(&ndev->req_lock);
test_bit(NCI_UP, &ndev->flags); |
...                             | test_and_clear_bit(NCI_UP, &ndev->flags)
mutex_lock(&ndev->req_lock);    |
                                |

This race will allow __nci_request() to be awaked while the device is
getting removed.

Similar to commit e2cb6b891a ("bluetooth: eliminate the potential race
condition when removing the HCI controller"). this patch alters the
function sequence in nci_request() to prevent the data races between the
nci_close_device().

Signed-off-by: Lin Ma <linma@zju.edu.cn>
Fixes: 6a2968aaf5 ("NFC: basic NCI protocol implementation")
Link: https://lore.kernel.org/r/20211115145600.8320-1-linma@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-11-17 20:16:53 -08:00
2021-11-12 09:23:16 +10:00
2021-11-11 09:34:35 -08:00
2021-11-12 09:23:16 +10:00
…

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