netdev - Re: [net-next 11/12] igbvf: convert msleep to mdelay in atomic context

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Message-ID: <20170815193210.GC27768@psuche>
Date:   Tue, 15 Aug 2017 13:32:11 -0600
From:   Greg Edwards <gedwards@....com>
To:     'Jeff Kirsher' <jeffrey.t.kirsher@...el.com>,
        David Laight <David.Laight@...LAB.COM>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "nhorman@...hat.com" <nhorman@...hat.com>,
        "sassmann@...hat.com" <sassmann@...hat.com>,
        "jogreene@...hat.com" <jogreene@...hat.com>
Subject: Re: [net-next 11/12] igbvf: convert msleep to mdelay in atomic
 context

On Mon, Aug 14, 2017 at 10:17:31AM +0000, David Laight wrote:
> From: Jeff Kirsher
>> Sent: 09 August 2017 22:48
>> From: Greg Edwards <gedwards@....com>
>>
>> This fixes a "scheduling while atomic" splat seen with
>> CONFIG_DEBUG_ATOMIC_SLEEP enabled.
>>
>> Signed-off-by: Greg Edwards <gedwards@....com>
>> Tested-by: Aaron Brown <aaron.f.brown@...el.com>
>> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
>> ---
>>  drivers/net/ethernet/intel/igbvf/vf.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igbvf/vf.c b/drivers/net/ethernet/intel/igbvf/vf.c
>> index 1d3aa9adcaa8..9577ccf4b26a 100644
>> --- a/drivers/net/ethernet/intel/igbvf/vf.c
>> +++ b/drivers/net/ethernet/intel/igbvf/vf.c
>> @@ -149,7 +149,7 @@ static s32 e1000_reset_hw_vf(struct e1000_hw *hw)
>>  		msgbuf[0] = E1000_VF_RESET;
>>  		mbx->ops.write_posted(hw, msgbuf, 1);
>>
>> -		msleep(10);
>> +		mdelay(10);
>
> Spinning for 10ms seems somewhat sub-optimal

Jeff,

Do we even need this delay?  The subsequent read_posted() will poll for
the PF's mailbox reply for up to 1s.

Greg