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Subject: Re: [PATCH RESEND] net/cisco: Fix a sleep-in-atomic-context bug in
 enic_init_affinity_hint()
To:     Jakub Kicinski <kuba@kernel.org>
References: <1592899989-22049-1-git-send-email-likaige@loongson.cn>
 <20200623135007.3105d067@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Christian Benvenuti <benve@cisco.com>,
        Govindarajulu Varadarajan <_govind@gmx.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Tiezhu Yang <yangtiezhu@loongson.cn>
From:   Kaige Li <likaige@loongson.cn>
Message-ID: <f12f40fe-7c9a-6ba8-f2ff-daf315030258@loongson.cn>
Date:   Wed, 24 Jun 2020 10:07:16 +0800
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On 06/24/2020 04:50 AM, Jakub Kicinski wrote:
> On Tue, 23 Jun 2020 16:13:09 +0800 Kaige Li wrote:
>> The kernel module may sleep with holding a spinlock.
>>
>> The function call paths (from bottom to top) are:
>>
>> [FUNC] zalloc_cpumask_var(GFP_KERNEL)
>> drivers/net/ethernet/cisco/enic/enic_main.c, 125: zalloc_cpumask_var in enic_init_affinity_hint
>> drivers/net/ethernet/cisco/enic/enic_main.c, 1918: enic_init_affinity_hint in enic_open
>> drivers/net/ethernet/cisco/enic/enic_main.c, 2348: enic_open in enic_reset
>> drivers/net/ethernet/cisco/enic/enic_main.c, 2341: spin_lock in enic_reset
>>
>> To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.
>>
>> Signed-off-by: Kaige Li <likaige@loongson.cn>
> I don't think this is sufficient. Calling open with a spin lock held
> seems like a very bad idea. At a quick look the driver also calls
> request_irq() from open - request_irq() can sleep.

You are right. Should I do spin_unlock before the enic_open, or remove
spin_lock in enic_reset?

Thank you.