| Message ID | 20211115145600.8320-1-linma@zju.edu.cn (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 86cdf8e38792545161dbe3350a7eced558ba4d15 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v1] NFC: reorganize the functions in nci_request | expand |
Hi there,
Compared to the version-0 patch, this patch add fixes tag in the patch file
+ Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
Best regards
Lin
On 15/11/2021 15:57, Lin Ma wrote: > Hi there, > > Compared to the version-0 patch, this patch add fixes tag in the patch file > > + Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation") Changelog goes either as cover letter (git help format-patch) or after '---' separator to individual patch. Best regards, Krzysztof
Hello: This patch was applied to netdev/net.git (master) by Jakub Kicinski <kuba@kernel.org>: On Mon, 15 Nov 2021 22:56:00 +0800 you wrote: > 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); | > | > > [...] Here is the summary with links: - [v1] NFC: reorganize the functions in nci_request https://git.kernel.org/netdev/net/c/86cdf8e38792 You are awesome, thank you!
diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c index 6fd873aa86be..1dd0269c1a72 100644 --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -144,12 +144,15 @@ inline int nci_request(struct nci_dev *ndev, { int rc; - if (!test_bit(NCI_UP, &ndev->flags)) - return -ENETDOWN; - /* Serialize all requests */ mutex_lock(&ndev->req_lock); - rc = __nci_request(ndev, req, opt, timeout); + /* check the state after obtaing the lock against any races + * from nci_close_device when the device gets removed. + */ + if (test_bit(NCI_UP, &ndev->flags)) + rc = __nci_request(ndev, req, opt, timeout); + else + rc = -ENETDOWN; mutex_unlock(&ndev->req_lock); return rc;
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 e2cb6b891ad2 ("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: 6a2968aaf50c ("NFC: basic NCI protocol implementation") --- net/nfc/nci/core.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)