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Message-ID: <39c6bc5c-8c91-4c91-a694-e27fa435f082@kylinos.cn>
Date: Mon, 22 Jan 2024 16:41:14 +0800
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Subject: Re: [PATCH v2] x86/xen: Add some null pointer checking to smp.c
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To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Markus Elfring <Markus.Elfring@web.de>, xen-devel@lists.xenproject.org,
 kernel-janitors@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
 kernel test robot <lkp@intel.com>,
 Boris Ostrovsky <boris.ostrovsky@oracle.com>, Borislav Petkov
 <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>,
 "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
 =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= <jgross@suse.com>,
 Thomas Gleixner <tglx@linutronix.de>, x86@kernel.org
References: <20240117090018.152031-1-chentao@kylinos.cn>
 <1705655941162581.825.seg@mailgw>
 <517fae75-c4e7-4576-81ff-6a14a3eb9cd7@kylinos.cn>
 <dfb6de51-3ebc-41fc-a750-cf5ca2ac05aa@moroto.mountain>
From: Kunwu Chan <chentao@kylinos.cn>
In-Reply-To: <dfb6de51-3ebc-41fc-a750-cf5ca2ac05aa@moroto.mountain>
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On 2024/1/22 16:30, Dan Carpenter wrote:
> On Fri, Jan 19, 2024 at 05:22:25PM +0800, Kunwu Chan wrote:
>> On 2024/1/17 18:40, Markus Elfring wrote:
>>>> kasprintf() returns a pointer to dynamically allocated memory
>>>> which can be NULL upon failure. Ensure the allocation was successful
>>>> by checking the pointer validity.
>>> =E2=80=A6
>>>> +++ b/arch/x86/xen/smp.c
>>>> @@ -61,10 +61,14 @@ void xen_smp_intr_free(unsigned int cpu)
>>>>
>>>>    int xen_smp_intr_init(unsigned int cpu)
>>>>    {
>>>> -	int rc;
>>>> +	int rc =3D 0;
>>>
>>> I find the indication of a successful function execution sufficient b=
y
>>> the statement =E2=80=9Creturn 0;=E2=80=9D at the end.
>>> How do you think about to omit such an extra variable initialisation?
>> Thanks, it's no need now. I'll remove it in v3.
>=20
> This advice is good.  Don't do unnecessary assignments.
Thanks for your suggestions, I'll keep it in mind.
>=20
>>>
>>>
>>>>    	char *resched_name, *callfunc_name, *debug_name;
>>>>
>>>>    	resched_name =3D kasprintf(GFP_KERNEL, "resched%d", cpu);
>>>> +	if (!resched_name) {
>>>> +		rc =3D -ENOMEM;
>>>> +		goto fail;
>>>> +	}
>>>>    	per_cpu(xen_resched_irq, cpu).name =3D resched_name;
>>>>    	rc =3D bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
>>>>    				    cpu,
>>>
>>> You propose to apply the same error code in four if branches.
>>> I suggest to avoid the specification of duplicate assignment statemen=
ts
>>> for this purpose.
>>> How do you think about to use another label like =E2=80=9Ce_nomem=E2=80=
=9D?
>> I'll add a new label to simply the code.
>=20
> I'm not a Xen maintainer so I can't really comment on their style
> choices.  However, as one of the kernel-janitors list people, I would
> say that not everyone agrees with Markus's style preferences.  Markus
> was banned from the list for a while, but we unbanned everyone when we
> transitioned to the new list infrastructure.  Do a search on lore to
> find out more.  https://lore.kernel.org/all/?q=3DElfring
>=20
> Perhaps wait for feedback from the maintainers for how to proceed?
OK, I'll wait for the feedback.
>=20
> regards,
> dan carpenter
>=20
--=20
Thanks,
   Kunwu