netdev - Re: [PATCH net-next v2 09/15] ice: protect init and calibrating check in ice_ptp_request

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Message-ID: <73b634db-13fe-dd02-614a-7d1453c3834d@intel.com>
Date:   Wed, 7 Dec 2022 16:29:54 -0800
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Saeed Mahameed <saeed@...nel.org>,
        Tony Nguyen <anthony.l.nguyen@...el.com>
CC:     <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
        <edumazet@...gle.com>, <netdev@...r.kernel.org>,
        <richardcochran@...il.com>, <leon@...nel.org>,
        Gurucharan G <gurucharanx.g@...el.com>
Subject: Re: [PATCH net-next v2 09/15] ice: protect init and calibrating check
 in ice_ptp_request_ts



On 12/7/2022 3:36 PM, Saeed Mahameed wrote:
> On 07 Dec 13:09, Tony Nguyen wrote:
>> From: Jacob Keller <jacob.e.keller@...el.com>
>>
>> When requesting a new timestamp, the ice_ptp_request_ts function does not
>> hold the Tx tracker lock while checking init and calibrating. This means
>> that we might issue a new timestamp request just after the Tx timestamp
>> tracker starts being deinitialized. This could lead to incorrect 
>> access of
>> the timestamp structures. Correct this by moving the init and calibrating
>> checks under the lock, and updating the flows which modify these 
>> fields to
>> use the lock.
>>
>> Note that we do not need to hold the lock while checking for tx->init in
>> ice_ptp_tstamp_tx. This is because the teardown function will use
>> synchronize_irq after clearing the flag to ensure that the threaded
> 
> FYI: couldn't find any ice_ptp_tstamp_tx(), and if it's running in xmit
> path sofritrq then sync_irq won't help you.
> 

I think that's a typo in the commit message, woops. It should be the 
following flow:

ice_misc_intr_thread_fn() -> ice_ptp_process_ts() -> ice_ptp_tx_tstamp()

the ice_misc_intr_thread_fn is a threaded IRQ function for 
ice_misc_intr. I believe from reading the kernel doc that 
synchronize_irq will work for threaded IRQ function.

Thanks,
Jake