netdev - RE: [PATCH] wifi: iwlwifi: ptp: Fix potential race condition in PTP removal

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Message-ID: <DM3PPF63A6024A9E1EF4081E342AF4BED81A365A@DM3PPF63A6024A9.namprd11.prod.outlook.com>
Date: Mon, 9 Feb 2026 08:32:03 +0000
From: "Korenblit, Miriam Rachel" <miriam.rachel.korenblit@...el.com>
To: "Cao, Junjie" <junjie.cao@...el.com>, "Berg, Johannes"
	<johannes.berg@...el.com>, "linux-wireless@...r.kernel.org"
	<linux-wireless@...r.kernel.org>, Richard Cochran <richardcochran@...il.com>
CC: Simon Horman <horms@...nel.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Ben Shimol, Yedidya"
	<yedidya.ben.shimol@...el.com>, "Stern, Avraham" <avraham.stern@...el.com>,
	"Gabay, Daniel" <daniel.gabay@...el.com>, "Prabhu, Krishnanand"
	<krishnanand.prabhu@...el.com>, "Coelho, Luciano" <luciano.coelho@...el.com>,
	Gregory Greenman <gregory.greenman@...el.com>, "stable@...r.kernel.org"
	<stable@...r.kernel.org>
Subject: RE: [PATCH] wifi: iwlwifi: ptp: Fix potential race condition in PTP
 removal



> -----Original Message-----
> From: Cao, Junjie <junjie.cao@...el.com>
> Sent: Thursday, January 15, 2026 6:15 PM
> To: Korenblit, Miriam Rachel <miriam.rachel.korenblit@...el.com>; Berg,
> Johannes <johannes.berg@...el.com>; linux-wireless@...r.kernel.org; Richard
> Cochran <richardcochran@...il.com>
> Cc: Simon Horman <horms@...nel.org>; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; Ben Shimol, Yedidya <yedidya.ben.shimol@...el.com>;
> Stern, Avraham <avraham.stern@...el.com>; Gabay, Daniel
> <daniel.gabay@...el.com>; Prabhu, Krishnanand
> <krishnanand.prabhu@...el.com>; Coelho, Luciano <luciano.coelho@...el.com>;
> Gregory Greenman <gregory.greenman@...el.com>; stable@...r.kernel.org
> Subject: [PATCH] wifi: iwlwifi: ptp: Fix potential race condition in PTP removal
> 
> iwl_mvm_ptp_remove() and iwl_mld_ptp_remove() call
> cancel_delayed_work_sync() only after ptp_clock_unregister() and after partially
> clearing ptp_data state.
> 
> This creates a race where the delayed work (iwl_mvm_ptp_work /
> iwl_mld_ptp_work) can run while teardown is in progress and observe a partially
> modified PTP state. In addition, the work may re-arm itself, extending the
> teardown window and risking execution after driver resources have been
> released.

Not sure I understand how is the fact that work re-arm itself is related/makes the bug worse?

> 
> Move cancel_delayed_work_sync() before ptp_clock_unregister() to ensure the
> delayed work is fully stopped before any PTP cleanup begins. This follows the
> standard pattern used by other Intel PTP drivers such as e1000e, igb, ixgbe, and
> ice.
> 
> Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
> Fixes: 1595ecce1cf3 ("wifi: iwlwifi: mvm: add support for PTP HW clock (PHC)")
> Cc: stable@...r.kernel.org
> Signed-off-by: Junjie Cao <junjie.cao@...el.com>
> ---
>  drivers/net/wireless/intel/iwlwifi/mld/ptp.c | 2 +-
> drivers/net/wireless/intel/iwlwifi/mvm/ptp.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
> b/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
> index 231920425c06..b40182320801 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
> @@ -319,10 +319,10 @@ void iwl_mld_ptp_remove(struct iwl_mld *mld)
>  			       mld->ptp_data.ptp_clock_info.name,
>  			       ptp_clock_index(mld->ptp_data.ptp_clock));
> 
> +		cancel_delayed_work_sync(&mld->ptp_data.dwork);
>  		ptp_clock_unregister(mld->ptp_data.ptp_clock);
>  		mld->ptp_data.ptp_clock = NULL;
>  		mld->ptp_data.last_gp2 = 0;
>  		mld->ptp_data.wrap_counter = 0;
> -		cancel_delayed_work_sync(&mld->ptp_data.dwork);
>  	}
>  }
> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c
> b/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c
> index 1da6260e238c..2b01ca36a1b5 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c
> @@ -325,11 +325,11 @@ void iwl_mvm_ptp_remove(struct iwl_mvm *mvm)
>  			       mvm->ptp_data.ptp_clock_info.name,
>  			       ptp_clock_index(mvm->ptp_data.ptp_clock));
> 
> +		cancel_delayed_work_sync(&mvm->ptp_data.dwork);
>  		ptp_clock_unregister(mvm->ptp_data.ptp_clock);
>  		mvm->ptp_data.ptp_clock = NULL;
>  		memset(&mvm->ptp_data.ptp_clock_info, 0,
>  		       sizeof(mvm->ptp_data.ptp_clock_info));
>  		mvm->ptp_data.last_gp2 = 0;
> -		cancel_delayed_work_sync(&mvm->ptp_data.dwork);
>  	}
>  }
> --
> 2.43.0