From: Kees Cook <keescook@chromium.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>,
Patrick Bellasi <patrick.bellasi@arm.com>,
linux-sparse@vger.kernel.org, Mao Wenan <maowenan@huawei.com>,
davem@davemloft.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH net-next] net: can: Fix compiling warning
Date: Mon, 12 Aug 2019 10:19:27 -0700 [thread overview]
Message-ID: <201908121001.0AC0A90@keescook> (raw)
In-Reply-To: <20190807105042.GK1974@kadam>
On Wed, Aug 07, 2019 at 01:50:42PM +0300, Dan Carpenter wrote:
> On Tue, Aug 06, 2019 at 06:41:44PM +0200, Oliver Hartkopp wrote:
> > I compiled the code (the original version), but I do not get that "Should it
> > be static?" warning:
> >
> > user@box:~/net-next$ make C=1
> > CALL scripts/checksyscalls.sh
> > CALL scripts/atomic/check-atomics.sh
> > DESCEND objtool
> > CHK include/generated/compile.h
> > CHECK net/can/af_can.c
> > ./include/linux/sched.h:609:43: error: bad integer constant expression
> > ./include/linux/sched.h:609:73: error: invalid named zero-width bitfield
> > `value'
> > ./include/linux/sched.h:610:43: error: bad integer constant expression
> > ./include/linux/sched.h:610:67: error: invalid named zero-width bitfield
> > `bucket_id'
> > CC [M] net/can/af_can.o
>
> The sched.h errors suppress Sparse warnings so it's broken/useless now.
> The code looks like this:
>
> include/linux/sched.h
> 613 struct uclamp_se {
> 614 unsigned int value : bits_per(SCHED_CAPACITY_SCALE);
> 615 unsigned int bucket_id : bits_per(UCLAMP_BUCKETS);
> 616 unsigned int active : 1;
> 617 unsigned int user_defined : 1;
> 618 };
>
> bits_per() is zero and Sparse doesn't like zero sized bitfields.
I just noticed these sparse warnings too -- what's happening here? Are
they _supposed_ to be 0-width fields? It doesn't look like it to me:
CONFIG_UCLAMP_BUCKETS_COUNT=5
...
#define UCLAMP_BUCKETS CONFIG_UCLAMP_BUCKETS_COUNT
...
unsigned int bucket_id : bits_per(UCLAMP_BUCKETS);
I would expect this to be 3 bits wide. ... Looks like gcc agrees:
struct uclamp_se {
unsigned int value:11; /* 0: 0 4 */
unsigned int bucket_id:3; /* 0:11 4 */
...
So this is a sparse issue?
--
Kees Cook
next prev parent reply other threads:[~2019-08-12 17:19 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 3:36 [PATCH net-next] net: can: Fix compiling warning Mao Wenan
2019-08-02 8:10 ` Oliver Hartkopp
2019-08-02 8:39 ` maowenan
2019-08-06 13:52 ` Dan Carpenter
2019-08-06 16:41 ` Oliver Hartkopp
2019-08-07 10:50 ` Dan Carpenter
2019-08-12 17:19 ` Kees Cook [this message]
2019-08-13 12:48 ` Dan Carpenter
2019-08-12 5:48 ` maowenan
2019-08-12 8:11 ` Oliver Hartkopp
2019-08-02 8:59 ` Sergei Shtylyov
2019-08-05 1:13 ` maowenan
2019-08-05 1:26 ` [PATCH net-next v2] " Mao Wenan
2019-08-05 10:56 ` [v2] " Markus Elfring
2019-08-05 11:57 ` [PATCH net-next v3] net: can: Fix compiling warnings for two functions Mao Wenan
2019-08-05 17:30 ` David Miller
2019-08-06 1:37 ` [PATCH net-next v4] " Mao Wenan
2019-08-06 11:37 ` [v4] " Markus Elfring
2019-08-06 14:40 ` [PATCH net-next v5] net: can: Fix sparse " Mao Wenan
2019-08-05 1:22 [PATCH net-next] net: can: Fix compiling warning Mao Wenan
2019-08-05 1:22 ` maowenan
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