[Precise][PATCH] mtip32xx: removed the irrelevant argument of mtip_hw_submit_io() and the unused member of struct driver_data

[Tim Gardner]

On 03/30/2012 12:12 PM, James M Leddy wrote:
> On 03/30/2012 01:11 PM, Tim Gardner wrote:
>> On 03/30/2012 10:14 AM, James M Leddy wrote:
>>> From: Asai Thambi S P <asamymuthupa at micron.com>
>>>
>>> Removed the following:
>>> 	* irrelevant argument 'barrier' of mtip_hw_submit_io()
>>> 	* unused member 'eh_active' of struct driver_data
>>>
>>> Signed-off-by: Asai Thambi S P <asamymuthupa at micron.com>
>>> Signed-off-by: Sam Bradshaw <sbradshaw at micron.com>
>>> Signed-off-by: Jens Axboe <axboe at kernel.dk>
>>> (cherry picked from commit 4e8670e26135d8fbfd5e084fddc1a8ed9f8eb4cb)
>>>
>>> From the merge:
>>>
>>>   - Killing the barrier part of mtip32xx.  It doesn't really support
>>>     barriers, and it doesn't need them (writes are fully ordered).
>>>
>>> Follow on from mtip32xx support that was added in 3.2.0-13.22.
>>> I have compile tested.
>>>
>>> Signed-off-by: James M Leddy <james.leddy at canonical.com>
>>> ---
>>>  drivers/block/mtip32xx/mtip32xx.c |   11 +++++------
>>>  drivers/block/mtip32xx/mtip32xx.h |    5 -----
>>>  2 files changed, 5 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
>>> index b74eab7..8eb81c9 100644
>>> --- a/drivers/block/mtip32xx/mtip32xx.c
>>> +++ b/drivers/block/mtip32xx/mtip32xx.c
>>> @@ -2068,8 +2068,6 @@ static int mtip_hw_ioctl(struct driver_data *dd, unsigned int cmd,
>>>   *	     when the read completes.
>>>   * @data     Callback data passed to the callback function
>>>   *	     when the read completes.
>>> - * @barrier  If non-zero, this command must be completed before
>>> - *	     issuing any other commands.
>>>   * @dir      Direction (read or write)
>>>   *
>>>   * return value
>>> @@ -2077,7 +2075,7 @@ static int mtip_hw_ioctl(struct driver_data *dd, unsigned int cmd,
>>>   */
>>>  static void mtip_hw_submit_io(struct driver_data *dd, sector_t start,
>>>  			      int nsect, int nents, int tag, void *callback,
>>> -			      void *data, int barrier, int dir)
>>> +			      void *data, int dir)
>>>  {
>>>  	struct host_to_dev_fis	*fis;
>>>  	struct mtip_port *port = dd->port;
>>> @@ -2108,8 +2106,6 @@ static void mtip_hw_submit_io(struct driver_data *dd, sector_t start,
>>>  	*((unsigned int *) &fis->lba_low) = (start & 0xFFFFFF);
>>>  	*((unsigned int *) &fis->lba_low_ex) = ((start >> 24) & 0xFFFFFF);
>>>  	fis->device	 = 1 << 6;
>>> -	if (barrier)
>>> -		fis->device |= FUA_BIT;
>>>  	fis->features    = nsect & 0xFF;
>>>  	fis->features_ex = (nsect >> 8) & 0xFF;
>>>  	fis->sect_count  = ((tag << 3) | (tag >> 5));
>>> @@ -3087,7 +3083,6 @@ static void mtip_make_request(struct request_queue *queue, struct bio *bio)
>>>  				tag,
>>>  				bio_endio,
>>>  				bio,
>>> -				bio->bi_rw & REQ_FUA,
>>>  				bio_data_dir(bio));
>>>  	} else
>>>  		bio_io_error(bio);
>>> @@ -3187,6 +3182,10 @@ skip_create_disk:
>>>  	blk_queue_max_segments(dd->queue, MTIP_MAX_SG);
>>>  	blk_queue_physical_block_size(dd->queue, 4096);
>>>  	blk_queue_io_min(dd->queue, 4096);
>>> +	/*
>>> +	 * write back cache is not supported in the device. FUA depends on
>>> +	 * write back cache support, hence setting flush support to zero.
>>> +	 */
>>>  	blk_queue_flush(dd->queue, 0);
>>>  
>>>  	/* Set the capacity of the device in 512 byte sectors. */
>>> diff --git a/drivers/block/mtip32xx/mtip32xx.h b/drivers/block/mtip32xx/mtip32xx.h
>>> index 723d7c4..e0554a8 100644
>>> --- a/drivers/block/mtip32xx/mtip32xx.h
>>> +++ b/drivers/block/mtip32xx/mtip32xx.h
>>> @@ -104,9 +104,6 @@
>>>  /* BAR number used to access the HBA registers. */
>>>  #define MTIP_ABAR		5
>>>  
>>> -/* Forced Unit Access Bit */
>>> -#define FUA_BIT			0x80
>>> -
>>>  #ifdef DEBUG
>>>   #define dbg_printk(format, arg...)	\
>>>  	printk(pr_fmt(format), ##arg);
>>> @@ -415,8 +412,6 @@ struct driver_data {
>>>  
>>>  	atomic_t resumeflag; /* Atomic variable to track suspend/resume */
>>>  
>>> -	atomic_t eh_active; /* Flag for error handling tracking */
>>> -
>>>  	struct task_struct *mtip_svc_handler; /* task_struct of svc thd */
>>>  };
>>>  
>>
>> Does this have an actual impact on driver performance or functionality ?
> 
> I'm not sure, I'll ask the reporter.
> 

Side channel information indicates that this patch has no impact on
functionality or performance, and therefore does not fix a bug making it
unsuitable as a stable update.

NAK
-- 
Tim Gardner tim.gardner at canonical.com