linux-kernel - Re: [RFC] block: remove never-modified global variable

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Date:	Tue, 19 May 2015 10:19:12 +0300
From:	Boaz Harrosh <boaz@...xistor.com>
To:	Brian Norris <computersforpeace@...il.com>,
	Jens Axboe <axboe@...com>
CC:	linux-kernel@...r.kernel.org, Christoph Hellwig <hch@...radead.org>
Subject: Re: [RFC] block: remove never-modified global variable

On 05/19/2015 02:08 AM, Brian Norris wrote:
> AFAICT, 'warn_no_part' never takes (and never has? at least, not in the
> git history) taken a value besides 1. It also has a disgruntled warning
> comment next to it, suggesting it shouldn't be there at all.
> 
> Signed-off-by: Brian Norris <computersforpeace@...il.com>
> Cc: Christoph Hellwig <hch@...radead.org>
> Cc: Boaz Harrosh <boaz@...xistor.com>

Reviewed-by: Boaz Harrosh <boaz@...xistor.com>

I have also tested it by returning error from read of sector zero.
And the print prints. Of course. No one ever turns it off.

Some comments

> Cc: Jens Axboe <axboe@...com>
> ---
> Only compile tested for now, as it's trivial. Just an RFC, since I don't really
> understand the context of why this (or the comment) is here in the first place.
> I just ran across this in code reading.
> 
>  block/partitions/amiga.c | 10 ++++------
>  block/partitions/check.c |  7 ++-----
>  block/partitions/check.h |  2 --
>  3 files changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
> index 2b13533d60a2..9dbf1cec7152 100644
> --- a/block/partitions/amiga.c
> +++ b/block/partitions/amiga.c
> @@ -41,9 +41,8 @@ int amiga_partition(struct parsed_partitions *state)
>  			goto rdb_done;
>  		data = read_part_sector(state, blk, &sect);
>  		if (!data) {
> -			if (warn_no_part)
> -				pr_err("Dev %s: unable to read RDB block %d\n",
> -				       bdevname(state->bdev, b), blk);
> +			pr_err("Dev %s: unable to read RDB block %d\n",
> +			       bdevname(state->bdev, b), blk);
>  			res = -1;
>  			goto rdb_done;
>  		}
> @@ -84,9 +83,8 @@ int amiga_partition(struct parsed_partitions *state)
>  		blk *= blksize;	/* Read in terms partition table understands */
>  		data = read_part_sector(state, blk, &sect);
>  		if (!data) {
> -			if (warn_no_part)
> -				pr_err("Dev %s: unable to read partition block %d\n",
> -				       bdevname(state->bdev, b), blk);
> +			pr_err("Dev %s: unable to read partition block %d\n",
> +			       bdevname(state->bdev, b), blk);
>  			res = -1;
>  			goto rdb_done;
>  		}
> diff --git a/block/partitions/check.c b/block/partitions/check.c
> index 16118d11dbfc..513c601b7874 100644
> --- a/block/partitions/check.c
> +++ b/block/partitions/check.c
> @@ -36,8 +36,6 @@
>  #include "sysv68.h"
>  #include "cmdline.h"
>  
> -int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
> -
>  static int (*check_part[])(struct parsed_partitions *) = {
>  	/*
>  	 * Probe partition formats with tables at disk address 0
> @@ -185,9 +183,8 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
>  	/* The partition is unrecognized. So report I/O errors if there were any */
>  		res = err;
>  	if (res) {
> -		if (warn_no_part)
> -			strlcat(state->pp_buf,
> -				" unable to read partition table\n", PAGE_SIZE);
> +		strlcat(state->pp_buf,
> +			" unable to read partition table\n", PAGE_SIZE);

OK I admit this was kind of very dumb before, If theoretically warn_no_part
would be false then the system would print "disk_name:\n" and nothing
else.

But specially now that you are unconditionally printing it. It is better
to just combine the two statements. See suggested patch below:

>  		printk(KERN_INFO "%s", state->pp_buf);
>  	}
>  
> diff --git a/block/partitions/check.h b/block/partitions/check.h
> index eade17ea910b..e09fac216adc 100644
> --- a/block/partitions/check.h
> +++ b/block/partitions/check.h
> @@ -50,5 +50,3 @@ put_partition(struct parsed_partitions *p, int n, sector_t from, sector_t size)
>  	}
>  }
>  
> -extern int warn_no_part;
> -
> 

diff --git a/block/partitions/check.c b/block/partitions/check.c
index 513c601..5fd2b7e 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -182,11 +182,9 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 	if (err)
 	/* The partition is unrecognized. So report I/O errors if there were any */
 		res = err;
-	if (res) {
-		strlcat(state->pp_buf,
-			" unable to read partition table\n", PAGE_SIZE);
-		printk(KERN_INFO "%s", state->pp_buf);
-	}
+	if (res)
+		printk(KERN_INFO "%s unable to read partition table\n",
+		       state->pp_buf);
 
 	free_page((unsigned long)state->pp_buf);
 	free_partitions(state);

Thanks
Boaz

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