From: Joe Perches <joe@perches.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>
Cc: David Laight <David.Laight@aculab.com>,
Bernard Metzler <bmt@zurich.ibm.com>,
Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
linux-rdma <linux-rdma@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] RDMA/siw: Fix compiler warnings on 32-bit due to u64/pointer abuse
Date: Tue, 27 Aug 2019 11:33:19 -0700 [thread overview]
Message-ID: <b0fe444622e32af6c34f3326e5dce3513adf5113.camel@perches.com> (raw)
In-Reply-To: <CAMuHMdW0jEpE3YrA5Znq8O9e4eswARwYYerEhRLSLWxeXMbsEQ@mail.gmail.com>
On Tue, 2019-08-27 at 19:59 +0200, Geert Uytterhoeven wrote:
> On Tue, Aug 27, 2019 at 7:46 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> > On Tue, Aug 27, 2019 at 07:29:52PM +0200, Geert Uytterhoeven wrote:
> > > On Tue, Aug 27, 2019 at 4:17 PM David Laight <David.Laight@aculab.com> wrote:
> > > > From: Geert Uytterhoeven
> > > > > Sent: 19 August 2019 18:15
> > > > ...
> > > > > > I think a cast to unsigned long is rather more common.
> > > > > >
> > > > > > uintptr_t is used ~1300 times in the kernel.
> > > > > > I believe a cast to unsigned long is much more common.
btw: apparently that's not true.
This grep may be incomplete but it seems there are fewer
kernel uses of a cast to unsigned long then pointer:
$ git grep -P '\(\s*\w+(\s+\w+){0,3}(\s*\*)+\s*\)\s*\(\s*unsigned\s+long\s*\)'|wc -l
423
Maybe add a cast_to_ptr macro like
#define cast_to_ptr(type, val) ((type)(uintptr_t)(val))
though that may not save any horizontal space
and/or a checkpatch test like:
---
scripts/checkpatch.pl | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 287fe73688f0..4ec88bc53f2f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6281,6 +6281,15 @@ sub process {
}
}
+# check for casts to pointer with intermediate casts to (unsigned long) not (uintptr_t)
+ if ($line =~ /\(\s*\w+(?:\s+\w+){0,3}(?:\s*\*){1,4}\s*\)\s*\(\s*unsigned\s+long\s*\)/) {
+ if (WARN("PREFER_UINTPTR_T",
+ "prefer intermediate cast to uintptr_t\n" . $herecurr) &&
+ $fix) {
+ $fixed[$fixlinenr] =~ s/(\(\s*\w+(?:\s+\w+){0,3}(?:\s*\*){1,4}\s*\))\s*\(\s*unsigned\s+long\s*\)/$1(uintptr_t)/;
+ }
+ }
+
# check for pointless casting of alloc functions
if ($line =~ /\*\s*\)\s*$allocFunctions\b/) {
WARN("UNNECESSARY_CASTS",
next prev parent reply other threads:[~2019-08-27 18:33 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 10:05 [PATCH] RDMA/siw: Fix compiler warnings on 32-bit due to u64/pointer abuse Geert Uytterhoeven
2019-08-19 12:24 ` Jason Gunthorpe
2019-08-19 13:36 ` Bernard Metzler
2019-08-19 13:52 ` Jason Gunthorpe
2019-08-19 14:15 ` Bernard Metzler
2019-08-19 14:18 ` Jason Gunthorpe
2019-08-19 14:52 ` Bernard Metzler
2019-08-19 15:07 ` Jason Gunthorpe
2019-08-19 15:54 ` Bernard Metzler
2019-08-19 16:05 ` Jason Gunthorpe
2019-08-19 16:29 ` Bernard Metzler
2019-08-19 16:35 ` Jason Gunthorpe
2019-08-19 17:39 ` Bernard Metzler
2019-08-19 18:00 ` Jason Gunthorpe
2019-08-19 21:40 ` Bernard Metzler
2019-08-19 22:22 ` Jason Gunthorpe
2019-08-19 16:56 ` Joe Perches
2019-08-19 17:14 ` Geert Uytterhoeven
2019-08-27 14:17 ` David Laight
2019-08-27 17:29 ` Geert Uytterhoeven
2019-08-27 17:46 ` Al Viro
2019-08-27 17:59 ` Geert Uytterhoeven
2019-08-27 18:33 ` Joe Perches [this message]
2019-08-28 8:27 ` David Laight
2019-08-19 17:26 ` Bernard Metzler
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