From: Christoph Hellwig <hch@infradead.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Yao Hongbo <yaohongbo@linux.alibaba.com>,
mst@redhat.com, alikernel-developer@linux.alibaba.com,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] uio/uio_pci_generic: Introduce refcnt on open/release
Date: Thu, 14 Apr 2022 23:47:14 -0700 [thread overview]
Message-ID: <YlkU8pLLlbo4WgQC@infradead.org> (raw)
In-Reply-To: <YlZ8vZ9RX5i7mWNk@kroah.com>
On Wed, Apr 13, 2022 at 09:33:17AM +0200, Greg KH wrote:
> On Wed, Apr 13, 2022 at 03:01:42PM +0800, Yao Hongbo wrote:
> > If two userspace programs both open the PCI UIO fd, when one
> > of the program exits uncleanly, the other will cause IO hang
> > due to bus-mastering disabled.
> >
> > It's a common usage for spdk/dpdk to use UIO. So, introduce refcnt
> > to avoid such problems.
>
> Why do you have multiple userspace programs opening the same device?
> Shouldn't they coordinate?
Independent of that (very valid) question I think the current code is
just broken. Either we need to prohbit multiple opens or do this kind
of refcounting.
prev parent reply other threads:[~2022-04-15 6:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-13 7:01 [PATCH v2] uio/uio_pci_generic: Introduce refcnt on open/release Yao Hongbo
2022-04-13 7:33 ` Greg KH
2022-04-13 8:51 ` Michael S. Tsirkin
2022-04-13 9:25 ` Yao Hongbo
2022-04-13 9:43 ` Greg KH
2022-04-13 11:09 ` Yao Hongbo
2022-04-13 11:20 ` Greg KH
2022-04-15 6:47 ` Christoph Hellwig [this message]
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