Re: [Intel-wired-lan] [PATCH net-next 2/5] iavf: simplify mutex_trylock+sleep loops

[Michal Schmidt <mschmidt@redhat.com>]

Dne 10. 10. 23 v 13:30 Drewek, Wojciech napsal:
>> -----Original Message-----
>> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
>> Michal Schmidt
>> Sent: Tuesday, October 10, 2023 2:25 AM
>> To: intel-wired-lan@lists.osuosl.org
>> Cc: Nguyen, Anthony L <anthony.l.nguyen@intel.com>; Radoslaw Tyl
>> <radoslawx.tyl@intel.com>; Brandeburg, Jesse <jesse.brandeburg@intel.com>
>> Subject: [Intel-wired-lan] [PATCH net-next 2/5] iavf: simplify
>> mutex_trylock+sleep loops
>>
>> This pattern appears in two places in the iavf source code:
>>    while (!mutex_trylock(...))
>>        usleep_range(...);
> 
> I found a few other places with similar pattern (iavf_configure_clsflower e.g).
> Do you think we can fix them as well?

I think so. But those are with some sort of a timeout, so replacing them 
would be slightly less obviously correct than these here. Later.
Michal

>> That's just mutex_lock with extra steps.
>> The pattern is a leftover from when iavf used bit flags instead of
>> mutexes for locking. Commit 5ac49f3c2702 ("iavf: use mutexes for locking
>> of critical sections") replaced test_and_set_bit with !mutex_trylock,
>> preserving the pattern.
>>
>> Simplify it to mutex_lock.
>>
>> Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
>> ---
>>   drivers/net/ethernet/intel/iavf/iavf_main.c | 6 ++----
>>   1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c
>> b/drivers/net/ethernet/intel/iavf/iavf_main.c
>> index 98ecf5d5a2f2..03156ca523fe 100644
>> --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
>> +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
>> @@ -3016,8 +3016,7 @@ static void iavf_reset_task(struct work_struct
>> *work)
>>   		return;
>>   	}
>>
>> -	while (!mutex_trylock(&adapter->client_lock))
>> -		usleep_range(500, 1000);
>> +	mutex_lock(&adapter->client_lock);
>>   	if (CLIENT_ENABLED(adapter)) {
>>   		adapter->flags &= ~(IAVF_FLAG_CLIENT_NEEDS_OPEN |
>>   				    IAVF_FLAG_CLIENT_NEEDS_CLOSE |
>> @@ -5069,8 +5068,7 @@ static int __maybe_unused iavf_suspend(struct
>> device *dev_d)
>>
>>   	netif_device_detach(netdev);
>>
>> -	while (!mutex_trylock(&adapter->crit_lock))
>> -		usleep_range(500, 1000);
>> +	mutex_lock(&adapter->crit_lock);
>>
>>   	if (netif_running(netdev)) {
>>   		rtnl_lock();
>> --
>> 2.41.0
>>
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> 

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