Re: [PATCH 3/3] nvme: use helper nvme_ctrl_state in nvme_keep_alive_end_io function

[Nilay Shroff <nilay@linux.ibm.com>]

On 10/29/24 20:31, Keith Busch wrote:
> On Sun, Oct 27, 2024 at 10:32:06PM +0530, Nilay Shroff wrote:
>> We no more need acquiring ctrl->lock before accessing the
>> NVMe controller state and instead we can now use the helper
>> nvme_ctrl_state. So replace the use of ctrl->lock from
>> nvme_keep_alive_end_io function with nvme_ctrl_state call.
>>
>> Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
>> ---
>>  drivers/nvme/host/core.c | 11 +++--------
>>  1 file changed, 3 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>> index 865c00ea19e3..6e814daf1002 100644
>> --- a/drivers/nvme/host/core.c
>> +++ b/drivers/nvme/host/core.c
>> @@ -1296,10 +1296,9 @@ static enum rq_end_io_ret nvme_keep_alive_end_io(struct request *rq,
>>  						 blk_status_t status)
>>  {
>>  	struct nvme_ctrl *ctrl = rq->end_io_data;
>> -	unsigned long flags;
>> -	bool startka = false;
>>  	unsigned long rtt = jiffies - (rq->deadline - rq->timeout);
>>  	unsigned long delay = nvme_keep_alive_work_period(ctrl);
>> +	enum nvme_ctrl_state state = nvme_ctrl_state(ctrl->state);
>>  
>>  	/*
>>  	 * Subtract off the keepalive RTT so nvme_keep_alive_work runs
>> @@ -1324,13 +1323,9 @@ static enum rq_end_io_ret nvme_keep_alive_end_io(struct request *rq,
>>  
>>  	ctrl->ka_last_check_time = jiffies;
>>  	ctrl->comp_seen = false;
>> -	spin_lock_irqsave(&ctrl->lock, flags);
>> -	if (ctrl->state == NVME_CTRL_LIVE ||
>> -	    ctrl->state == NVME_CTRL_CONNECTING)
>> -		startka = true;
>> -	spin_unlock_irqrestore(&ctrl->lock, flags);
>> -	if (startka)
>> +	if (state == NVME_CTRL_LIVE || state == NVME_CTRL_CONNECTING)
>>  		queue_delayed_work(nvme_wq, &ctrl->ka_work, delay);
>> +
>>  	return RQ_END_IO_NONE;
>>  }
> 
> This restores what you had in the reverted patch, which was a
> significant portion of the diff stat. If we're keeping this chunk, maybe
> a full revert isn't necessary, and we can squash the series to just one
> fixing commit.
> 
This doesn't exactly restore what was reverted in the patch. If you 
closely look at the reverted patch then you would find that we reverted 
the nvme_keep_alive_finish function which is not exactly same as 
nvme_keep_alive_end_io function. We renamed nvme_keep_alive_end_io() 
to nvme_keep_alive_finish() for the upstream patch.     

So the revert patch restores nvme_keep_alive_end_io function and also 
restores the nvme_keep_alive_work changes. Then the current patch in this 
patchset, actually works upon nvme_keep_alive_end_io function.
 
Thanks,
--Nilay