From: Anton Ivanov <anton.ivanov@cambridgegreys.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Song Liu <songliubraving@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Richard Weinberger <richard@nod.at>,
Jeff Dike <jdike@addtoit.com>,
kernel-janitors@vger.kernel.org,
Alexei Starovoitov <ast@kernel.org>,
linux-um@lists.infradead.org,
Wei Yongjun <weiyongjun1@huawei.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Martin KaFai Lau <kafai@fb.com>
Subject: Re: [PATCH -next] um: vector: use GFP_ATOMIC under spin lock
Date: Thu, 28 Nov 2019 09:22:59 +0000 [thread overview]
Message-ID: <69f4767b-c095-571d-92cf-343bfb17bfc0@cambridgegreys.com> (raw)
In-Reply-To: <20191128083735.GE1781@kadam>
On 28/11/2019 08:37, Dan Carpenter wrote:
> On Thu, Nov 28, 2019 at 08:18:30AM +0000, Anton Ivanov wrote:
>>
>>
>> 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@huawei.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.
>>
>
> Do you have CONFIG_DEBUG_ATOMIC_SLEEP enabled? The GFP_KERNEL calls
> should have triggered a warning if so.
I do not think we can use that in um.
config DEBUG_ATOMIC_SLEEP
bool "Sleep inside atomic section checking"
select PREEMPT_COUNT
depends on DEBUG_KERNEL
depends on !ARCH_NO_PREEMPT
In arch/um/Kconfig
select ARCH_NO_PREEMPT
Brgds,
>
> regards,
> dan carpenter
>
>
> _______________________________________________
> linux-um mailing list
> linux-um@lists.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/
next prev parent reply other threads:[~2019-11-28 9:23 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 2:01 [PATCH -next] um: vector: use GFP_ATOMIC under spin lock Wei Yongjun
2019-11-28 7:51 ` Anton Ivanov
2019-11-28 8:06 ` Dan Carpenter
2019-11-28 8:18 ` Anton Ivanov
2019-11-28 8:37 ` Dan Carpenter
2019-11-28 9:22 ` Anton Ivanov [this message]
2019-11-28 8:41 ` Richard Weinberger
2019-11-28 9:24 ` Anton Ivanov
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