From: Haakon Bugge <haakon.bugge@oracle.com>
To: Leon Romanovsky <leon@kernel.org>
Cc: Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Christian Benvenuti <benve@cisco.com>,
Dan Carpenter <dan.carpenter@oracle.com>,
OFED mailing list <linux-rdma@vger.kernel.org>,
Nelson Escobar <neescoba@cisco.com>
Subject: Re: [PATCH rdma-rc] RDMA/usnic: Lock VF with mutex instead of spinlock
Date: Mon, 13 Sep 2021 12:50:58 +0000 [thread overview]
Message-ID: <AC729233-CCB2-4A90-A7B2-08E534C3B1F1@oracle.com> (raw)
In-Reply-To: <YT8LYZvhYm/kT7Kb@unreal>
> On 13 Sep 2021, at 10:27, Leon Romanovsky <leon@kernel.org> wrote:
>
> On Mon, Sep 13, 2021 at 08:17:00AM +0000, Haakon Bugge wrote:
>>
>>
>>> On 13 Sep 2021, at 10:04, Leon Romanovsky <leon@kernel.org> wrote:
>>>
>>> From: Leon Romanovsky <leonro@nvidia.com>
>>>
>>> Usnic VF doesn't need lock in atomic context to create QPs, so it is safe
>>> to use mutex instead of spinlock. Such change fixes the following smatch
>>> error.
>>
>> s/GFP_ATOMIC/GFP_KERNEL/ in find_free_vf_and_create_qp_grp() as well?
>
> Do you mean in usnic_uiom_get_dev_list()?
Sorry, my comments was v5.14.1 centric. For latest upstream, its alloc_res_chunk_list(),
find_free_vf_and_create_qp_grp()
-> usnic_ib_qp_grp_create
-> alloc_res_chunk_list()
> That GFP_ATOMIC existed before my patch while we are holding usdev_lock mutex.
True.
> Anyway, I prefer to touch that driver as less as possible.
>
> The allocations can continue to be with GFP_ATOMIC while we use mutex.
> It is bad thing, but not a necessary to fix bug. We just wasting atomic
> memory and instruct kernel do not sleep while
> doing allocations.
I assume this driver is not very much maintained by Cisco, hence, I agree with your rationale above,
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Thxs, Håkon
next prev parent reply other threads:[~2021-09-13 12:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 8:04 Leon Romanovsky
2021-09-13 8:17 ` Haakon Bugge
2021-09-13 8:27 ` Leon Romanovsky
2021-09-13 12:50 ` Haakon Bugge [this message]
2021-09-23 5:34 ` Leon Romanovsky
2021-09-24 13:59 ` Jason Gunthorpe
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