netdev - Re: [PATCH -next] um: vector: use GFP_ATOMIC under spin lock

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Message-ID: <5892ee7c-ff24-fb3c-6911-44e0b1d5895f@cambridgegreys.com>
Date:   Thu, 28 Nov 2019 08:18:30 +0000
From:   Anton Ivanov <anton.ivanov@...bridgegreys.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Wei Yongjun <weiyongjun1@...wei.com>
Cc:     Song Liu <songliubraving@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        kernel-janitors@...r.kernel.org,
        Richard Weinberger <richard@....at>,
        Jeff Dike <jdike@...toit.com>, linux-um@...ts.infradead.org,
        Alexei Starovoitov <ast@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Martin KaFai Lau <kafai@...com>
Subject: Re: [PATCH -next] um: vector: use GFP_ATOMIC under spin lock

On 28/11/2019 08:06, Dan Carpenter wrote:
> On Thu, Nov 28, 2019 at 02:01:47AM +0000, Wei Yongjun wrote:
>> A spin lock is taken here so we should use GFP_ATOMIC.
>>
>> Fixes: 9807019a62dc ("um: Loadable BPF "Firmware" for vector drivers")
>> Signed-off-by: Wei Yongjun <weiyongjun1@...wei.com>
>> ---
>>   arch/um/drivers/vector_kern.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
>> index 92617e16829e..6ff0065a271d 100644
>> --- a/arch/um/drivers/vector_kern.c
>> +++ b/arch/um/drivers/vector_kern.c
>> @@ -1402,7 +1402,7 @@ static int vector_net_load_bpf_flash(struct net_device *dev,
>>   		kfree(vp->bpf->filter);
>>   		vp->bpf->filter = NULL;
>>   	} else {
>> -		vp->bpf = kmalloc(sizeof(struct sock_fprog), GFP_KERNEL);
>> +		vp->bpf = kmalloc(sizeof(struct sock_fprog), GFP_ATOMIC);
>>   		if (vp->bpf == NULL) {
>>   			netdev_err(dev, "failed to allocate memory for firmware\n");
>>   			goto flash_fail;
>> @@ -1414,7 +1414,7 @@ static int vector_net_load_bpf_flash(struct net_device *dev,
>>   	if (request_firmware(&fw, efl->data, &vdevice->pdev.dev))
>              ^^^^^^^^^^^^^^^^
> 
> Is it really possible to call request_firmware() while holding a
> spin_lock?  I was so sure that read from the disk.

Works, I tested the patch quite a few times.

> 
> regards,
> dan carpenter
> 
>>   		goto flash_fail;
>>   
>> -	vp->bpf->filter = kmemdup(fw->data, fw->size, GFP_KERNEL);
>> +	vp->bpf->filter = kmemdup(fw->data, fw->size, GFP_ATOMIC);
>>   	if (!vp->bpf->filter)
>>   		goto free_buffer;
>>
>>
> 
> _______________________________________________
> linux-um mailing list
> linux-um@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-um
> 

-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/

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