linux-kernel - Re: [PATCH] block: Remove redundant assignments

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Date:   Sat, 9 Apr 2022 05:01:41 -0700
From:   Tom Rix <trix@...hat.com>
To:     Michal Orzel <michalorzel.eng@...il.com>,
        Jens Axboe <axboe@...nel.dk>,
        "Richard Russon (FlatCap)" <ldm@...tcap.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-ntfs-dev@...ts.sourceforge.net, llvm@...ts.linux.dev
Subject: Re: [PATCH] block: Remove redundant assignments


On 4/9/22 3:19 AM, Michal Orzel wrote:
> Get rid of redundant assignments which end up in values not being
> read either because they are overwritten or the function ends.

This log is the same as your last patch.

Instead of a general statement on deadstores, a more specific

analysis of the setting being removed would be helpful.

This will mean splitting the patch to match the analysis.

Tom

>
> Reported by clang-tidy [deadcode.DeadStores]
>
> Signed-off-by: Michal Orzel <michalorzel.eng@...il.com>
> ---
>   block/badblocks.c        |  2 --
>   block/blk-map.c          |  5 ++---
>   block/partitions/acorn.c |  4 ++--
>   block/partitions/atari.c |  1 -
>   block/partitions/ldm.c   | 15 +++------------
>   5 files changed, 7 insertions(+), 20 deletions(-)
>
> diff --git a/block/badblocks.c b/block/badblocks.c
> index d39056630d9c..3afb550c0f7b 100644
> --- a/block/badblocks.c
> +++ b/block/badblocks.c
> @@ -65,7 +65,6 @@ int badblocks_check(struct badblocks *bb, sector_t s, int sectors,
>   		s >>= bb->shift;
>   		target += (1<<bb->shift) - 1;
>   		target >>= bb->shift;
> -		sectors = target - s;
>   	}
>   	/* 'target' is now the first block after the bad range */
>   
> @@ -345,7 +344,6 @@ int badblocks_clear(struct badblocks *bb, sector_t s, int sectors)
>   		s += (1<<bb->shift) - 1;
>   		s >>= bb->shift;
>   		target >>= bb->shift;
> -		sectors = target - s;
>   	}
>   
>   	write_seqlock_irq(&bb->lock);
> diff --git a/block/blk-map.c b/block/blk-map.c
> index c7f71d83eff1..fa72e63e18c2 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -260,10 +260,9 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
>   
>   		npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
>   
> -		if (unlikely(offs & queue_dma_alignment(rq->q))) {
> -			ret = -EINVAL;
> +		if (unlikely(offs & queue_dma_alignment(rq->q)))
>   			j = 0;
> -		} else {
> +		else {
>   			for (j = 0; j < npages; j++) {
>   				struct page *page = pages[j];
>   				unsigned int n = PAGE_SIZE - offs;
> diff --git a/block/partitions/acorn.c b/block/partitions/acorn.c
> index 2c381c694c57..d2fc122d7426 100644
> --- a/block/partitions/acorn.c
> +++ b/block/partitions/acorn.c
> @@ -282,13 +282,13 @@ int adfspart_check_ADFS(struct parsed_partitions *state)
>   #ifdef CONFIG_ACORN_PARTITION_RISCIX
>   		case PARTITION_RISCIX_SCSI:
>   		case PARTITION_RISCIX_MFM:
> -			slot = riscix_partition(state, start_sect, slot,
> +			riscix_partition(state, start_sect, slot,
>   						nr_sects);
>   			break;
>   #endif
>   
>   		case PARTITION_LINUX:
> -			slot = linux_partition(state, start_sect, slot,
> +			linux_partition(state, start_sect, slot,
>   					       nr_sects);
>   			break;
>   		}
> diff --git a/block/partitions/atari.c b/block/partitions/atari.c
> index da5994175416..9655c728262a 100644
> --- a/block/partitions/atari.c
> +++ b/block/partitions/atari.c
> @@ -140,7 +140,6 @@ int atari_partition(struct parsed_partitions *state)
>   				/* accept only GEM,BGM,RAW,LNX,SWP partitions */
>   				if (!((pi->flg & 1) && OK_id(pi->id)))
>   					continue;
> -				part_fmt = 2;
>   				put_partition (state, slot,
>   						be32_to_cpu(pi->st),
>   						be32_to_cpu(pi->siz));
> diff --git a/block/partitions/ldm.c b/block/partitions/ldm.c
> index 27f6c7d9c776..38e58960ae03 100644
> --- a/block/partitions/ldm.c
> +++ b/block/partitions/ldm.c
> @@ -736,7 +736,6 @@ static bool ldm_parse_cmp3 (const u8 *buffer, int buflen, struct vblk *vb)
>   		len = r_cols;
>   	} else {
>   		r_stripe = 0;
> -		r_cols   = 0;
>   		len = r_parent;
>   	}
>   	if (len < 0)
> @@ -783,11 +782,8 @@ static int ldm_parse_dgr3 (const u8 *buffer, int buflen, struct vblk *vb)
>   		r_id1 = ldm_relative (buffer, buflen, 0x24, r_diskid);
>   		r_id2 = ldm_relative (buffer, buflen, 0x24, r_id1);
>   		len = r_id2;
> -	} else {
> -		r_id1 = 0;
> -		r_id2 = 0;
> +	} else
>   		len = r_diskid;
> -	}
>   	if (len < 0)
>   		return false;
>   
> @@ -826,11 +822,8 @@ static bool ldm_parse_dgr4 (const u8 *buffer, int buflen, struct vblk *vb)
>   		r_id1 = ldm_relative (buffer, buflen, 0x44, r_name);
>   		r_id2 = ldm_relative (buffer, buflen, 0x44, r_id1);
>   		len = r_id2;
> -	} else {
> -		r_id1 = 0;
> -		r_id2 = 0;
> +	} else
>   		len = r_name;
> -	}
>   	if (len < 0)
>   		return false;
>   
> @@ -963,10 +956,8 @@ static bool ldm_parse_prt3(const u8 *buffer, int buflen, struct vblk *vb)
>   			return false;
>   		}
>   		len = r_index;
> -	} else {
> -		r_index = 0;
> +	} else
>   		len = r_diskid;
> -	}
>   	if (len < 0) {
>   		ldm_error("len %d < 0", len);
>   		return false;