Re: [PATCH] igb_uio: stop device when closing /dev/uioX

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-12-02 16:45, Jianfeng Tan:
> Depends-on: http://dpdk.org/dev/patchwork/patch/17493/

The above patch is marked as rejected.
Do we want to reject also this patch?

> When a DPDK application grab a PCI device, device and driver work
> together to Rx/Tx packets. If the DPDK app crashes or gets killed,
> there's no chance for DPDK driver to stop the device, which means
> rte_eth_dev_stop() will not be called.
> 
> This could result in problems. In virtio's case, the device (the
> vhost backend), will keep working. If packets come, the vhost will
> copy them into the vring, which is negotiated with the previous DPDK
> app. But the resources, especially hugepages, are recycled by VM
> kernel. What's worse, the memory could be allocated for other usage,
> and re-written. This leads to an uncertain situation. Like this post
> has reported, https://bugs.launchpad.net/qemu/+bug/1558175, QEMU's
> vhost finds out wrong value, and exits the whole QEMU process.
> 
> To make it right, we need to restart (or reset) the device and make
> the device go into the initial state, when uio-generic or igb_uio
> recycles the PCI device. There's a chance in uio framework to disable
> devices when /dev/uioX gets closed. Here we enable the pci device
> in open() hook and disable it in release() hook.
> 
> However, if device is not enabled in probe() phase any more, we can
> not register irq in probe() through uio_register_device(). To address
> that, we invoke request_irq() to register callback directly.
> 
> Similar change needs to be done in uio-generic driver. And vfio-pci
> seems to have done that already.
> 
> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>