linux-kernel - Re: [PATCH 2/2] staging: zram: remove init

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Message-ID: <20130906145949.GD2238@swordfish.minsk.epam.com>
Date:	Fri, 6 Sep 2013 17:59:49 +0300
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Jerome Marchand <jmarchan@...hat.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Minchan Kim <minchan@...nel.org>, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] staging: zram: remove init_done from zram struct

On (09/06/13 16:50), Jerome Marchand wrote:
> On 09/06/2013 03:52 PM, Sergey Senozhatsky wrote:
> > `zram->init_done != 0' equals to `zram->meta != NULL', so init_done
> > can be removed.
> 
> The name init_done is self explanatory, meta isn't. You could for
> instance write a function with an explicit name to test for
> initialization.

init_done are pretty useless 4 bytes, they just mimic `!!zram->meta'
value (or `zram->meta != NULL'). well, we can have a macro or inline
function to return `zram->meta != NULL'

	-ss

> Jerome
> 
> > 
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> > 
> > ---
> > 
> >  drivers/staging/zram/zram_drv.c | 18 +++++++-----------
> >  drivers/staging/zram/zram_drv.h |  1 -
> >  2 files changed, 7 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
> > index 17386e2..34b72ea 100644
> > --- a/drivers/staging/zram/zram_drv.c
> > +++ b/drivers/staging/zram/zram_drv.c
> > @@ -60,7 +60,7 @@ static ssize_t initstate_show(struct device *dev,
> >  {
> >  	struct zram *zram = dev_to_zram(dev);
> >  
> > -	return sprintf(buf, "%u\n", zram->init_done);
> > +	return sprintf(buf, "%u\n", zram->meta != NULL);
> >  }
> >  
> >  static ssize_t num_reads_show(struct device *dev,
> > @@ -133,7 +133,7 @@ static ssize_t mem_used_total_show(struct device *dev,
> >  	struct zram_meta *meta = zram->meta;
> >  
> >  	down_read(&zram->init_lock);
> > -	if (zram->init_done)
> > +	if (meta)
> >  		val = zs_get_total_size_bytes(meta->mem_pool);
> >  	up_read(&zram->init_lock);
> >  
> > @@ -556,14 +556,12 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
> >  	flush_work(&zram->free_work);
> >  
> >  	down_write(&zram->init_lock);
> > -	if (!zram->init_done) {
> > +	if (!zram->meta) {
> >  		up_write(&zram->init_lock);
> >  		return;
> >  	}
> >  
> >  	meta = zram->meta;
> > -	zram->init_done = 0;
> > -
> >  	/* Free all pages that are still in this zram device */
> >  	for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
> >  		unsigned long handle = meta->table[index].handle;
> > @@ -573,7 +571,7 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
> >  		zs_free(meta->mem_pool, handle);
> >  	}
> >  
> > -	zram_meta_free(zram->meta);
> > +	zram_meta_free(meta);
> >  	zram->meta = NULL;
> >  	/* Reset stats */
> >  	memset(&zram->stats, 0, sizeof(zram->stats));
> > @@ -602,9 +600,7 @@ static void zram_init_device(struct zram *zram, struct zram_meta *meta)
> >  
> >  	/* zram devices sort of resembles non-rotational disks */
> >  	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
> > -
> >  	zram->meta = meta;
> > -	zram->init_done = 1;
> >  
> >  	pr_debug("Initialization done!\n");
> >  }
> > @@ -623,7 +619,7 @@ static ssize_t disksize_store(struct device *dev,
> >  	disksize = PAGE_ALIGN(disksize);
> >  	meta = zram_meta_alloc(disksize);
> >  	down_write(&zram->init_lock);
> > -	if (zram->init_done) {
> > +	if (zram->meta) {
> >  		up_write(&zram->init_lock);
> >  		zram_meta_free(meta);
> >  		pr_info("Cannot change disksize for initialized device\n");
> > @@ -731,7 +727,7 @@ static void zram_make_request(struct request_queue *queue, struct bio *bio)
> >  	struct zram *zram = queue->queuedata;
> >  
> >  	down_read(&zram->init_lock);
> > -	if (unlikely(!zram->init_done))
> > +	if (unlikely(!zram->meta))
> >  		goto error;
> >  
> >  	if (!valid_io_request(zram, bio)) {
> > @@ -880,7 +876,7 @@ static int create_device(struct zram *zram, int device_id)
> >  		goto out_free_disk;
> >  	}
> >  
> > -	zram->init_done = 0;
> > +	zram->meta = NULL;
> >  	return 0;
> >  
> >  out_free_disk:
> > diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
> > index 97a3acf..b1100cf 100644
> > --- a/drivers/staging/zram/zram_drv.h
> > +++ b/drivers/staging/zram/zram_drv.h
> > @@ -110,7 +110,6 @@ struct zram {
> >  
> >  	struct request_queue *queue;
> >  	struct gendisk *disk;
> > -	int init_done;
> >  	/* Prevent concurrent execution of device init, reset and R/W request */
> >  	struct rw_semaphore init_lock;
> >  	/*
> > 
> > --
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> > 
> 
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