From: Michal Nazarewicz <mina86@mina86.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
Arnd Bergmann <arnd@arndb.de>,
Grant Likely <grant.likely@linaro.org>,
Laura Abbott <lauraa@codeaurora.org>,
Josh Cartwright <joshc@codeaurora.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Kyungmin Park <kyungmin.park@samsung.com>
Subject: Re: linux-next: build warnings after merge of the akpm-current tree
Date: Fri, 03 Oct 2014 21:28:17 +0200 [thread overview]
Message-ID: <xa1tr3yp2bse.fsf@mina86.com> (raw)
In-Reply-To: <20141003112154.92b5a47b2009293090d18f5a@linux-foundation.org>
On Fri, Oct 03 2014, Andrew Morton wrote:
> On Fri, 3 Oct 2014 17:30:04 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
>> Hi Andrew,
>>
>> After merging the akpm-current tree, today's linux-next build (arm
>> multi_v7_defconfig) produced these warnings:
>>
>> drivers/base/dma-contiguous.c:244:2: warning: initialization from incompatible pointer type
>> .device_init = rmem_cma_device_init,
>> ^
>> drivers/base/dma-contiguous.c:244:2: warning: (near initialization for 'rmem_cma_ops.device_init')
>> drivers/base/dma-coherent.c:303:2: warning: initialization from incompatible pointer type
>> .device_init = rmem_dma_device_init,
>> ^
>>
>> Introduced by commit e92f6296f3a2 ("drivers: dma-coherent: add
>> initialization from device tree"). This init routine is supposed to
>> return void ...
>
> I'm a bit reluctant to just go in and change rmem_cma_device_init().
>
> Why does it test for rmem->priv==NULL? Can that really happen? Why?
> Is it a legitimate state?
I don't think so, since:
static int __init rmem_cma_setup(struct reserved_mem *rmem)
{
[…]
rmem->ops = &rmem_cma_ops;
rmem->priv = cma;
[…]
}
The following should fix the warning:
diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
index 6c42289..a9a88b6 100644
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -223,14 +223,9 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages,
#undef pr_fmt
#define pr_fmt(fmt) fmt
-static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
+static void rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
{
- struct cma *cma = rmem->priv;
-
- if (!cma)
- return -ENODEV;
-
- dev_set_cma_area(dev, cma);
+ dev_set_cma_area(dev, rmem->priv);
return 0;
}
Even if rmem->priv is NULL, the call will simply clear device's
cma_area, but at this point it should be NULL anyway.
> And why does dev_set_cma_area() test for dev==NULL? Can that really
> happen? Is it legitimate? Is all this stuff just papering over other
> bugs?
I believe since a2547380393ac82c659b40182b0da8d05a8365f3 dev no longer
can be NULL. It should be safe to apply this:
diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h
index 569bbd0..ff9804e 100644
--- a/include/linux/dma-contiguous.h
+++ b/include/linux/dma-contiguous.h
@@ -71,8 +71,7 @@ static inline struct cma *dev_get_cma_area(struct device *dev)
static inline void dev_set_cma_area(struct device *dev, struct cma *cma)
{
- if (dev)
- dev->cma_area = cma;
+ dev->cma_area = cma;
}
static inline void dma_contiguous_set_default(struct cma *cma)
>
> The whole thing could do with a bit of an audit and cleanup, I suspect.
> Get the states and initialization sequences and error checking all
> sorted out, then get rid of all these tests for NULL.
>
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +--<mpn@google.com>--<xmpp:mina86@jabber.org>--ooO--(_)--Ooo--
next prev parent reply other threads:[~2014-10-03 19:28 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 7:30 linux-next: build warnings after merge of the akpm-current tree Stephen Rothwell
2014-10-03 18:21 ` Andrew Morton
2014-10-03 19:28 ` Michal Nazarewicz [this message]
-- strict thread matches above, loose matches on Subject: below --
2022-02-09 6:02 Stephen Rothwell
2022-02-09 16:03 ` Hugh Dickins
2022-03-28 23:04 ` Matthew Wilcox
2022-03-29 3:32 ` Hugh Dickins
2022-03-24 7:27 ` Stephen Rothwell
2022-03-28 19:54 ` Hugh Dickins
2022-03-28 22:10 ` Matthew Wilcox
2021-10-11 7:31 Stephen Rothwell
2021-10-11 17:46 ` Kees Cook
2021-06-15 10:50 Stephen Rothwell
2020-10-06 12:05 Stephen Rothwell
2020-10-06 20:01 ` Peter Xu
2020-10-06 22:03 ` Stephen Rothwell
2020-01-06 6:14 Stephen Rothwell
2017-08-24 7:41 Stephen Rothwell
2017-08-24 8:15 ` Changwei Ge
2017-08-25 21:23 ` Andrew Morton
2017-08-26 1:23 ` Changwei Ge
2017-03-20 5:22 Stephen Rothwell
2017-03-20 9:05 ` Dmitry Vyukov
2017-03-20 12:30 ` Jan Glauber
2017-03-20 17:06 ` Challa, Mahipal
2015-01-27 8:12 Stephen Rothwell
2015-01-27 8:27 ` Vladimir Davydov
2014-09-23 8:18 Stephen Rothwell
2014-08-26 7:22 Stephen Rothwell
2014-08-26 10:19 ` Xishi Qiu
2013-08-29 9:47 Stephen Rothwell
2013-08-29 11:24 ` Maxim Patlasov
2013-08-29 19:42 ` Andrew Morton
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