linux-kernel - Re: [PATCH -next] scsi: hisi_sas: drop free_irq of devm_request

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Date:   Wed, 19 May 2021 11:36:22 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     John Garry <john.garry@...wei.com>, <linux-kernel@...r.kernel.org>,
        <linux-scsi@...r.kernel.org>
CC:     <jejb@...ux.ibm.com>, <martin.petersen@...cle.com>,
        chenxiang <chenxiang66@...ilicon.com>,
        "luojiaxing@...wei.com" <luojiaxing@...wei.com>
Subject: Re: [PATCH -next] scsi: hisi_sas: drop free_irq of devm_request_irq
 allocated irq


On 2021/5/18 23:34, John Garry wrote:
> On 18/05/2021 14:09, Yang Yingliang wrote:
>> irq allocated with devm_request_irq should not be freed using
>> free_irq, because doing so causes a dangling pointer, and a
>> subsequent double free.
>>
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
>> ---
>>   drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c 
>> b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>> index 499c770d405c..684f762bcfb3 100644
>> --- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>> +++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>> @@ -4811,9 +4811,9 @@ hisi_sas_v3_destroy_irqs(struct pci_dev *pdev, 
>> struct hisi_hba *hisi_hba)
>>   {
>>       int i;
>>   -    free_irq(pci_irq_vector(pdev, 1), hisi_hba);
>> -    free_irq(pci_irq_vector(pdev, 2), hisi_hba);
>> -    free_irq(pci_irq_vector(pdev, 11), hisi_hba);
>> +    devm_free_irq(&pdev->dev, pci_irq_vector(pdev, 1), hisi_hba);
>> +    devm_free_irq(&pdev->dev, pci_irq_vector(pdev, 2), hisi_hba);
>> +    devm_free_irq(&pdev->dev, pci_irq_vector(pdev, 11), hisi_hba);
>>       for (i = 0; i < hisi_hba->cq_nvecs; i++) {
>>           struct hisi_sas_cq *cq = &hisi_hba->cq[i];
>>           int nr = hisi_sas_intr_conv ? 16 : 16 + i;
>>
>
> Does the free_irq(pci_irq_vector(pdev, nr, cq)) call also need to 
> change (not shown)?
Yes, I missed that, it should be changed too.
>
> Having said that, why have these at all if we use devm_request_irq()? 
> devm_irq_release() calls free_irq().
I keep the original logic here, only avoid double free.
>
> Thanks,
> John
>
> .