Re: [PATCH iwl-net v1] i40e: fix races in PTP external timestamp work handling

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 24/07/2026 10:34, xuanqiang.luo@linux.dev wrote:
> From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
> 
> The time sync interrupt queues ptp_extts0_work, which reads device
> registers and reports events through pf->ptp_clock.
> 
> i40e_ptp_stop() unregisters the PHC without first disabling the event
> source or draining the work. The worker can therefore access the clock or
> PF after either has been freed, causing a use-after-free. Disable external
> timestamp events and call disable_work_sync() before unregistering the PHC.
> Disabling the work also prevents an interrupt already in progress from
> queuing it after the drain.
> 
> INIT_WORK() is called from i40e_ptp_set_timestamp_mode(), which runs on
> reset and whenever timestamping is reconfigured. Reinitializing pending or
> running work can corrupt its workqueue state. Initialize the work once from
> i40e_sw_init() instead.
> 
> Also exclude reset recovery before stopping PTP so a concurrent rebuild
> cannot re-enable timestamp events or recreate the PHC during removal.
> 
> Fixes: 1050713026a0 ("i40e: add support for PTP external synchronization clock")
> Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
> ---
>   drivers/net/ethernet/intel/i40e/i40e.h      |  1 +
>   drivers/net/ethernet/intel/i40e/i40e_main.c | 17 +++++++-------
>   drivers/net/ethernet/intel/i40e/i40e_ptp.c  | 25 +++++++++++++++------
>   3 files changed, 28 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
> index 83e780919ac97..e2ae61bc38786 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
> @@ -1315,6 +1315,7 @@ int i40e_ptp_hwtstamp_set(struct net_device *netdev,
>   			  struct netlink_ext_ack *extack);
>   void i40e_ptp_save_hw_time(struct i40e_pf *pf);
>   void i40e_ptp_restore_hw_time(struct i40e_pf *pf);
> +void i40e_ptp_init_work(struct i40e_pf *pf);
>   void i40e_ptp_init(struct i40e_pf *pf);
>   void i40e_ptp_stop(struct i40e_pf *pf);
>   int i40e_ptp_alloc_pins(struct i40e_pf *pf);
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index a04683004a567..2909a58d57562 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -12819,6 +12819,7 @@ static int i40e_sw_init(struct i40e_pf *pf)
>   			 "total-port-shutdown was enabled, link-down-on-close is forced on\n");
>   	}
>   	mutex_init(&pf->switch_mutex);
> +	i40e_ptp_init_work(pf);
>   
>   sw_init_done:
>   	return err;
> @@ -16157,14 +16158,6 @@ static void i40e_remove(struct pci_dev *pdev)
>   
>   	i40e_devlink_unregister(pf);
>   
> -	i40e_dbg_pf_exit(pf);
> -
> -	i40e_ptp_stop(pf);
> -
> -	/* Disable RSS in hw */
> -	i40e_write_rx_ctl(hw, I40E_PFQF_HENA(0), 0);
> -	i40e_write_rx_ctl(hw, I40E_PFQF_HENA(1), 0);
> -
>   	/* Grab __I40E_RESET_RECOVERY_PENDING and set __I40E_IN_REMOVE
>   	 * flags, once they are set, i40e_rebuild should not be called as
>   	 * i40e_prep_for_reset always returns early.
> @@ -16173,6 +16166,14 @@ static void i40e_remove(struct pci_dev *pdev)
>   		usleep_range(1000, 2000);
>   	set_bit(__I40E_IN_REMOVE, pf->state);
>   
> +	i40e_dbg_pf_exit(pf);
> +
> +	i40e_ptp_stop(pf);
> +
> +	/* Disable RSS in hw */
> +	i40e_write_rx_ctl(hw, I40E_PFQF_HENA(0), 0);
> +	i40e_write_rx_ctl(hw, I40E_PFQF_HENA(1), 0);
> +
>   	if (test_bit(I40E_FLAG_SRIOV_ENA, pf->flags)) {
>   		set_bit(__I40E_VF_RESETS_DISABLED, pf->state);
>   		i40e_free_vfs(pf);
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_ptp.c b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
> index ff62b5f2c8150..fd51ab8c10c20 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_ptp.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
> @@ -169,6 +169,17 @@ static void i40e_ptp_extts0_work(struct work_struct *work)
>   	ptp_clock_event(pf->ptp_clock, &event);
>   }
>   
> +/**
> + * i40e_ptp_init_work - Initialize PTP work for a PF
> + * @pf: Board private structure
> + *
> + * Initialize work which must remain valid for the lifetime of the PF.
> + */
> +void i40e_ptp_init_work(struct i40e_pf *pf)
> +{
> +	INIT_WORK(&pf->ptp_extts0_work, i40e_ptp_extts0_work);
> +}
> +

why do you need extra function for a single line of code? why cannot you 
put it into i40e_ptp_init?

>   /**
>    * i40e_is_ptp_pin_dev - check if device supports PTP pins
>    * @hw: pointer to the hardware structure
> @@ -1186,8 +1197,6 @@ static int i40e_ptp_set_timestamp_mode(struct i40e_pf *pf,
>   	regval |= 1 << I40E_PRTTSYN_CTL0_EVENT_INT_ENA_SHIFT;
>   	wr32(hw, I40E_PRTTSYN_CTL0, regval);
>   
> -	INIT_WORK(&pf->ptp_extts0_work, i40e_ptp_extts0_work);
> -
>   	switch (config->tx_type) {
>   	case HWTSTAMP_TX_OFF:
>   		pf->ptp_tx = false;