Messages in this thread | | | Date | Wed, 13 Jul 2022 10:08:11 +0200 | From | Michael Walle <> | Subject | Re: [PATCH] NFC: nxp-nci: fix deadlock during firmware update |
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Am 2022-07-13 08:57, schrieb Krzysztof Kozlowski: > 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?
Mh, you are right. fw_info could be modified by the irq thread and in the worker thread (and the nfc core doesn't protect against multiple fw_download() calls)
-michael
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