2016-10-21 15:43:05

by Arnd Bergmann

[permalink] [raw]
Subject: [PATCH] block: zoned: fix harmless maybe-uninitialized warning

The blkdev_report_zones produces a harmless warning when
-Wmaybe-uninitialized is set, after gcc gets a little confused
about the multiple 'goto' here:

block/blk-zoned.c: In function 'blkdev_report_zones':
block/blk-zoned.c:188:13: error: 'nz' may be used uninitialized in this function [-Werror=maybe-uninitialized]

Moving the assignment to nr_zones makes this a little simpler
while also avoiding the warning reliably. I'm removing the
extraneous initialization of 'int ret' in the same patch, as
that is semi-related and could cause an uninitialized use of
that variable to not produce a warning.

Fixes: 6a0cb1bc106f ("block: Implement support for zoned block devices")
Signed-off-by: Arnd Bergmann <[email protected]>
---
block/blk-zoned.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 667f95d86695..472211fa183a 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -80,7 +80,7 @@ int blkdev_report_zones(struct block_device *bdev,
unsigned int i, n, nz;
unsigned int ofst;
void *addr;
- int ret = 0;
+ int ret;

if (!q)
return -ENXIO;
@@ -179,14 +179,12 @@ int blkdev_report_zones(struct block_device *bdev,

}

+ *nr_zones = nz;
out:
bio_for_each_segment_all(bv, bio, i)
__free_page(bv->bv_page);
bio_put(bio);

- if (ret == 0)
- *nr_zones = nz;
-
return ret;
}
EXPORT_SYMBOL_GPL(blkdev_report_zones);
--
2.9.0


2016-10-21 20:46:44

by Shaun Tancheff

[permalink] [raw]
Subject: Re: [PATCH] block: zoned: fix harmless maybe-uninitialized warning

On Fri, Oct 21, 2016 at 10:42 AM, Arnd Bergmann <[email protected]> wrote:
> The blkdev_report_zones produces a harmless warning when
> -Wmaybe-uninitialized is set, after gcc gets a little confused
> about the multiple 'goto' here:
>
> block/blk-zoned.c: In function 'blkdev_report_zones':
> block/blk-zoned.c:188:13: error: 'nz' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> Moving the assignment to nr_zones makes this a little simpler
> while also avoiding the warning reliably. I'm removing the
> extraneous initialization of 'int ret' in the same patch, as
> that is semi-related and could cause an uninitialized use of
> that variable to not produce a warning.
>
> Fixes: 6a0cb1bc106f ("block: Implement support for zoned block devices")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> block/blk-zoned.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 667f95d86695..472211fa183a 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -80,7 +80,7 @@ int blkdev_report_zones(struct block_device *bdev,
> unsigned int i, n, nz;
> unsigned int ofst;
> void *addr;
> - int ret = 0;
> + int ret;
>
> if (!q)
> return -ENXIO;
> @@ -179,14 +179,12 @@ int blkdev_report_zones(struct block_device *bdev,
>
> }
>
> + *nr_zones = nz;
> out:
> bio_for_each_segment_all(bv, bio, i)
> __free_page(bv->bv_page);
> bio_put(bio);
>
> - if (ret == 0)
> - *nr_zones = nz;
> -
> return ret;
> }
> EXPORT_SYMBOL_GPL(blkdev_report_zones);
> --
> 2.9.0

Reviewed-by: Shaun Tancheff <[email protected]>

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--
Shaun Tancheff

2016-10-23 23:38:55

by Damien Le Moal

[permalink] [raw]
Subject: Re: [PATCH] block: zoned: fix harmless maybe-uninitialized warning


On 10/22/16 00:42, Arnd Bergmann wrote:
> The blkdev_report_zones produces a harmless warning when
> -Wmaybe-uninitialized is set, after gcc gets a little confused
> about the multiple 'goto' here:
>
> block/blk-zoned.c: In function 'blkdev_report_zones':
> block/blk-zoned.c:188:13: error: 'nz' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> Moving the assignment to nr_zones makes this a little simpler
> while also avoiding the warning reliably. I'm removing the
> extraneous initialization of 'int ret' in the same patch, as
> that is semi-related and could cause an uninitialized use of
> that variable to not produce a warning.
>
> Fixes: 6a0cb1bc106f ("block: Implement support for zoned block devices")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> block/blk-zoned.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 667f95d86695..472211fa183a 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -80,7 +80,7 @@ int blkdev_report_zones(struct block_device *bdev,
> unsigned int i, n, nz;
> unsigned int ofst;
> void *addr;
> - int ret = 0;
> + int ret;
>
> if (!q)
> return -ENXIO;
> @@ -179,14 +179,12 @@ int blkdev_report_zones(struct block_device *bdev,
>
> }
>
> + *nr_zones = nz;
> out:
> bio_for_each_segment_all(bv, bio, i)
> __free_page(bv->bv_page);
> bio_put(bio);
>
> - if (ret == 0)
> - *nr_zones = nz;
> -
> return ret;
> }
> EXPORT_SYMBOL_GPL(blkdev_report_zones);

Reviewed-by: Damien Le Moal <[email protected]>

--
Damien Le Moal, Ph.D.
Sr. Manager, System Software Research Group,
Western Digital Corporation
[email protected]
(+81) 0466-98-3593 (ext. 513593)
1 kirihara-cho, Fujisawa,
Kanagawa, 252-0888 Japan
http://www.wdc.com, http://www.hgst.com

2016-10-25 01:01:21

by Martin K. Petersen

[permalink] [raw]
Subject: Re: [PATCH] block: zoned: fix harmless maybe-uninitialized warning

>>>>> "Arnd" == Arnd Bergmann <[email protected]> writes:

Arnd> The blkdev_report_zones produces a harmless warning when
Arnd> -Wmaybe-uninitialized is set, after gcc gets a little confused
Arnd> about the multiple 'goto' here:

Arnd> block/blk-zoned.c: In function 'blkdev_report_zones':
Arnd> block/blk-zoned.c:188:13: error: 'nz' may be used uninitialized in
Arnd> this function [-Werror=maybe-uninitialized]

Arnd> Moving the assignment to nr_zones makes this a little simpler
Arnd> while also avoiding the warning reliably. I'm removing the
Arnd> extraneous initialization of 'int ret' in the same patch, as that
Arnd> is semi-related and could cause an uninitialized use of that
Arnd> variable to not produce a warning.

Jens: Are you picking up Arnd's two fixes for the zoned code?

--
Martin K. Petersen Oracle Linux Engineering

2016-10-25 02:51:43

by Jens Axboe

[permalink] [raw]
Subject: Re: [PATCH] block: zoned: fix harmless maybe-uninitialized warning

On 10/24/2016 07:00 PM, Martin K. Petersen wrote:
>>>>>> "Arnd" == Arnd Bergmann <[email protected]> writes:
>
> Arnd> The blkdev_report_zones produces a harmless warning when
> Arnd> -Wmaybe-uninitialized is set, after gcc gets a little confused
> Arnd> about the multiple 'goto' here:
>
> Arnd> block/blk-zoned.c: In function 'blkdev_report_zones':
> Arnd> block/blk-zoned.c:188:13: error: 'nz' may be used uninitialized in
> Arnd> this function [-Werror=maybe-uninitialized]
>
> Arnd> Moving the assignment to nr_zones makes this a little simpler
> Arnd> while also avoiding the warning reliably. I'm removing the
> Arnd> extraneous initialization of 'int ret' in the same patch, as that
> Arnd> is semi-related and could cause an uninitialized use of that
> Arnd> variable to not produce a warning.
>
> Jens: Are you picking up Arnd's two fixes for the zoned code?

Yep, adding them now. Thanks Arnd.

--
Jens Axboe