linux-kernel - Re: [PATCH 09/14] swim3: clean up request completion paths

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Date:	Tue, 28 Apr 2009 16:44:50 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Tejun Heo <tj@...nel.org>
Cc:	axboe@...nel.dk, linux-kernel@...r.kernel.org, donari75@...il.com,
	bzolnier@...il.com, joerg@...chain.net, geert@...ux-m68k.org,
	davem@...emloft.net, jdike@...ux.intel.com, Laurent@...vier.info
Subject: Re: [PATCH 09/14] swim3: clean up request completion paths

On Tue, 2009-04-28 at 13:06 +0900, Tejun Heo wrote:
> swim3 curiously tries to update request parameters before calling
> __blk_end_request() when __blk_end_request() will do it anyway, and it
> updates request for partial completion manually instead of using
> blk_update_request().  Also, it does some spurious checks on rq such
> as testing whether rq->sector is negative or current_nr_sectors is
> zero right after fetching.
> 
> Drop unnecessary stuff and use standard block layer mechanisms.

That smells like historical stuff from floppy.c :-)

I'll try to dig a mac with a floppy drive to test that.

Cheers,
Ben.

> [ Impact: cleanup ]
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> ---
>  drivers/block/swim3.c |   31 +++++--------------------------
>  1 files changed, 5 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/block/swim3.c b/drivers/block/swim3.c
> index 5904f7b..4248559 100644
> --- a/drivers/block/swim3.c
> +++ b/drivers/block/swim3.c
> @@ -319,14 +319,10 @@ static void start_request(struct floppy_state *fs)
>  		       req->errors, req->current_nr_sectors);
>  #endif
>  
> -		if (req->sector < 0 || req->sector >= fs->total_secs) {
> +		if (req->sector >= fs->total_secs) {
>  			__blk_end_request_cur(req, -EIO);
>  			continue;
>  		}
> -		if (req->current_nr_sectors == 0) {
> -			__blk_end_request_cur(req, 0);
> -			continue;
> -		}
>  		if (fs->ejected) {
>  			__blk_end_request_cur(req, -EIO);
>  			continue;
> @@ -593,8 +589,6 @@ static void xfer_timeout(unsigned long data)
>  	struct floppy_state *fs = (struct floppy_state *) data;
>  	struct swim3 __iomem *sw = fs->swim3;
>  	struct dbdma_regs __iomem *dr = fs->dma;
> -	struct dbdma_cmd *cp = fs->dma_cmd;
> -	unsigned long s;
>  	int n;
>  
>  	fs->timeout_pending = 0;
> @@ -605,14 +599,6 @@ static void xfer_timeout(unsigned long data)
>  	out_8(&sw->intr_enable, 0);
>  	out_8(&sw->control_bic, WRITE_SECTORS | DO_ACTION);
>  	out_8(&sw->select, RELAX);
> -	if (rq_data_dir(fd_req) == WRITE)
> -		++cp;
> -	if (ld_le16(&cp->xfer_status) != 0)
> -		s = fs->scount - ((ld_le16(&cp->res_count) + 511) >> 9);
> -	else
> -		s = 0;
> -	fd_req->sector += s;
> -	fd_req->current_nr_sectors -= s;
>  	printk(KERN_ERR "swim3: timeout %sing sector %ld\n",
>  	       (rq_data_dir(fd_req)==WRITE? "writ": "read"), (long)fd_req->sector);
>  	__blk_end_request_cur(fd_req, -EIO);
> @@ -719,9 +705,7 @@ static irqreturn_t swim3_interrupt(int irq, void *dev_id)
>  		if (intr & ERROR_INTR) {
>  			n = fs->scount - 1 - resid / 512;
>  			if (n > 0) {
> -				fd_req->sector += n;
> -				fd_req->current_nr_sectors -= n;
> -				fd_req->buffer += n * 512;
> +				blk_update_request(fd_req, 0, n << 9);
>  				fs->req_sector += n;
>  			}
>  			if (fs->retries < 5) {
> @@ -745,13 +729,7 @@ static irqreturn_t swim3_interrupt(int irq, void *dev_id)
>  				start_request(fs);
>  				break;
>  			}
> -			fd_req->sector += fs->scount;
> -			fd_req->current_nr_sectors -= fs->scount;
> -			fd_req->buffer += fs->scount * 512;
> -			if (fd_req->current_nr_sectors <= 0) {
> -				__blk_end_request_cur(fd_req, 0);
> -				fs->state = idle;
> -			} else {
> +			if (__blk_end_request(fd_req, 0, fs->scount << 9)) {
>  				fs->req_sector += fs->scount;
>  				if (fs->req_sector > fs->secpertrack) {
>  					fs->req_sector -= fs->secpertrack;
> @@ -761,7 +739,8 @@ static irqreturn_t swim3_interrupt(int irq, void *dev_id)
>  					}
>  				}
>  				act(fs);
> -			}
> +			} else
> +				fs->state = idle;
>  		}
>  		if (fs->state == idle)
>  			start_request(fs);

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