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Date: Thu, 14 Mar 2024 12:00:27 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Paolo Abeni <pabeni@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@vger.kernel.org>, netdev <netdev@vger.kernel.org>,
 Yisen Zhuang <yisen.zhuang@huawei.com>, Salil Mehta
 <salil.mehta@huawei.com>, Jijie Shao <shaojijie@huawei.com>, "David S.
 Miller" <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Jakub
 Kicinski <kuba@kernel.org>, Yufeng Mo <moyufeng@huawei.com>, Huazhong Tan
 <tanhuazhong@huawei.com>
Subject: Re: [PATCH] net: hns3: tracing: fix hclgevf trace event strings
Message-ID: <20240314120027.088e850d@gandalf.local.home>
In-Reply-To: <8607787b42e80503e0259f41e0bcc2d3ff770355.camel@redhat.com>
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	<8607787b42e80503e0259f41e0bcc2d3ff770355.camel@redhat.com>
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On Thu, 14 Mar 2024 15:39:28 +0100
Paolo Abeni <pabeni@redhat.com> wrote:

> On Wed, 2024-03-13 at 09:34 -0400, Steven Rostedt wrote:
> > From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
> >=20
> > [
> >    Note, I need to take this patch through my tree, so I'm looking for =
acks. =20
>=20
> Note that this device driver is changing quite rapidly, so I expect
> some conflicts here later. I guess Liuns will have to handle them ;)

Well, it merges fine with linux-next and linus's current master. ;-)

>=20
> >    This causes the build to fail when I add the __assign_str() check, w=
hich
> >    I was about to push to Linus, but it breaks allmodconfig due to this=
 error.
> > ]
> >=20
> > The __string() and __assign_str() helper macros of the TRACE_EVENT() ma=
cro
> > are going through some optimizations where only the source string of
> > __string() will be used and the __assign_str() source will be ignored a=
nd
> > later removed.
> >=20
> > To make sure that there's no issues, a new check is added between the
> > __string() src argument and the __assign_str() src argument that does a
> > strcmp() to make sure they are the same string.
> >=20
> > The hclgevf trace events have:
> >=20
> >   __assign_str(devname, &hdev->nic.kinfo.netdev->name);
> >=20
> > Which triggers the warning:
> >=20
> > hclgevf_trace.h:34:39: error: passing argument 1 of =E2=80=98strcmp=E2=
=80=99 from incompatible pointer type [-Werror=3Dincompatible-pointer-types]
> >    34 |                 __assign_str(devname, &hdev->nic.kinfo.netdev->=
name);
> >  [..]
> > arch/x86/include/asm/string_64.h:75:24: note: expected =E2=80=98const c=
har *=E2=80=99 but argument is of type =E2=80=98char (*)[16]=E2=80=99
> >    75 | int strcmp(const char *cs, const char *ct);
> >       |            ~~~~~~~~~~~~^~
> >=20
> >=20
> > Because __assign_str() now has:
> >=20
> > 	WARN_ON_ONCE(__builtin_constant_p(src) ?		\
> > 		     strcmp((src), __data_offsets.dst##_ptr_) :	\
> > 		     (src) !=3D __data_offsets.dst##_ptr_);	\
> >=20
> > The problem is the '&' on hdev->nic.kinfo.netdev->name. That's because
> > that name is:
> >=20
> > 	char			name[IFNAMSIZ]
> >=20
> > Where passing an address '&' of a char array is not compatible with str=
cmp().
> >=20
> > The '&' is not necessary, remove it.
> >=20
> > Fixes: d8355240cf8fb ("net: hns3: add trace event support for PF/VF mai=
lbox") =20
>=20
> checkpactch in strict mode complains the hash is not 12 char long.

Hmm, I wonder why my git blame gives me 13 characters in the sha. (I cut
and pasted it from git blame). My git config has:

[core] =20
        abbrev =3D 12


>=20
> > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> =20
>=20
> FWIW
>=20
> Acked-by: Paolo Abeni <pabeni@redhat.com>

Thanks!

-- Steve