linux-kernel - Re: [PATCH v2] x86/xen: Add some null pointer checking to smp.c

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Date: Fri, 19 Jan 2024 17:22:25 +0800
From: Kunwu Chan <chentao@...inos.cn>
To: Markus Elfring <Markus.Elfring@....de>, xen-devel@...ts.xenproject.org,
 kernel-janitors@...r.kernel.org
Cc: LKML <linux-kernel@...r.kernel.org>, kernel test robot <lkp@...el.com>,
 Boris Ostrovsky <boris.ostrovsky@...cle.com>, Borislav Petkov
 <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
 Jürgen Groß <jgross@...e.com>,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org
Subject: Re: [PATCH v2] x86/xen: Add some null pointer checking to smp.c

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.
> …
>> +++ 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 = 0;
> 
> I find the indication of a successful function execution sufficient by
> the statement “return 0;” 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.
> 
> 
>>   	char *resched_name, *callfunc_name, *debug_name;
>>
>>   	resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
>> +	if (!resched_name) {
>> +		rc = -ENOMEM;
>> +		goto fail;
>> +	}
>>   	per_cpu(xen_resched_irq, cpu).name = resched_name;
>>   	rc = 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 statements
> for this purpose.
> How do you think about to use another label like “e_nomem”?
I'll add a new label to simply the code.
> 
> Regards,
> Markus
-- 
Thanks,
   Kunwu