Messages in this thread | | | Date | Wed, 13 Jul 2022 08:57:47 +0200 | Subject | Re: [PATCH] NFC: nxp-nci: fix deadlock during firmware update | From | Krzysztof Kozlowski <> |
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On 12/07/2022 17:25, Michael Walle wrote: > During firmware update, both nxp_nci_i2c_irq_thread_fn() and > nxp_nci_fw_work() will hold the info_lock mutex and one will wait > for the other via a completion: > > nxp_nci_fw_work() > mutex_lock(info_lock) > nxp_nci_fw_send() > wait_for_completion(cmd_completion) > mutex_unlock(info_lock) > > nxp_nci_i2c_irq_thread_fn() > mutex_lock(info_lock) > nxp_nci_fw_recv_frame() > complete(cmd_completion) > mutex_unlock(info_lock) > > This will result in a -ETIMEDOUT error during firmware update (note > that the wait_for_completion() above is a variant with a timeout). > > Drop the lock in nxp_nci_fw_work() and instead take it after the > work is done in nxp_nci_fw_work_complete() when the NFC controller mode > is switched and the info structure is updated. > > Fixes: dece45855a8b ("NFC: nxp-nci: Add support for NXP NCI chips") > Signed-off-by: Michael Walle <michael@walle.cc> > --- > drivers/nfc/nxp-nci/firmware.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/nfc/nxp-nci/firmware.c b/drivers/nfc/nxp-nci/firmware.c > index 119bf305c642..6a4d4aa7239f 100644 > --- a/drivers/nfc/nxp-nci/firmware.c > +++ b/drivers/nfc/nxp-nci/firmware.c > @@ -54,6 +54,7 @@ void nxp_nci_fw_work_complete(struct nxp_nci_info *info, int result) > struct nxp_nci_fw_info *fw_info = &info->fw_info; > int r; > > + mutex_lock(&info->info_lock); > if (info->phy_ops->set_mode) { > r = info->phy_ops->set_mode(info->phy_id, NXP_NCI_MODE_COLD); > if (r < 0 && result == 0) > @@ -66,6 +67,7 @@ void nxp_nci_fw_work_complete(struct nxp_nci_info *info, int result) > release_firmware(fw_info->fw); > fw_info->fw = NULL; > } > + mutex_unlock(&info->info_lock); > > nfc_fw_download_done(info->ndev->nfc_dev, fw_info->name, (u32) -result); > } > @@ -172,8 +174,6 @@ void nxp_nci_fw_work(struct work_struct *work) > fw_info = container_of(work, struct nxp_nci_fw_info, work); > info = container_of(fw_info, struct nxp_nci_info, fw_info); > > - mutex_lock(&info->info_lock); > -
I am not sure this is correct. info_lock should protect members of info thus also info->fw_info. By removing the mutex the protection is gone.
Unless you are sure that fw_info cannot be modified concurrently?
Best regards, Krzysztof
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