From: "Michael S. Tsirkin" <mst@redhat.com>
To: Juergen Gross <jgross@suse.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
Linux Virtualization <virtualization@lists.linux-foundation.org>
Subject: Re: Weird locking hierarchy in virtcrypto
Date: Fri, 22 Sep 2023 06:45:08 -0400 [thread overview]
Message-ID: <20230922064219-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <bdc81c97-ada4-41ef-89c4-7894201b46c2@suse.com>
On Fri, Sep 22, 2023 at 10:36:59AM +0200, Juergen Gross wrote:
> While backporting an upstream patch to one of our older distro kernels I've
> found a weird locking hierarchy in the virtio crypto driver:
>
> virtio_config_changed():
> spin_lock_irqsave()
> ->__virtio_config_changed()
> ->drv->config_changed() <- assume drv == virtio_crypto_driver
> virtcrypto_config_changed():
> ->virtcrypto_update_status()
> ->virtcrypto_dev_start()
> ->virtio_crypto_skcipher_algs_register()
> mutex_lock()
>
> I don't think trying to take a mutex while holding a spinlock with interrupts
> disabled is a proper thing to do.
>
> Am I overlooking something here?
>
>
> Juergen
Yes - this seems like a bug in virtcrypto - for example, virt blk
queues a work for this reason. It's so common that it might make
sense to move the config work into virtio core.
In any case, patches welcome.
--
MST
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prev parent reply other threads:[~2023-09-22 10:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-22 8:36 Weird locking hierarchy in virtcrypto Juergen Gross via Virtualization
2023-09-22 10:45 ` Michael S. Tsirkin [this message]
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