On Tue, Dec 12, 2017 at 11:10:32PM +0800, Ming Lei wrote: > On Tue, Dec 12, 2017 at 03:13:58PM +0100, Christoph Hellwig wrote: > > On Tue, Dec 12, 2017 at 07:02:32PM +0800, Ming Lei wrote: > > > It may cause race by setting 'nvmeq' in nvme_init_request() > > > because .init_request is called inside switching io scheduler, which > > > may happen when the NVMe device is being resetted and its nvme queues > > > are being freed and created. We don't have any sync between the two > > > pathes. > > > > > > This patch removes the .init_request callback and sets the nvmeq runtime, > > > and fixes the following bug: > > > > If ->init_request doesn't work for NVMe it won't work for any other > > driver either, so we need to remove it entirely if we can't fix it. > > > > I'd much rather try to fix it first, though. > > Just checked all this uses, and it is a NVMe specific issue, because only > NVMe's .init_request() associates reference of one variable to the request, > and the variable itself may change during the request's lifetime. > > And all the following .init_request() have this issue: > > nvme_fc_init_request() > nvme_rdma_init_request() > nvme_loop_init_request() After taking a close look, there isn't such issue actually on the above three cases because the lifetime of ctl->queues(and each element) are same with 'nvme_ctr/nvme_rdma_ctrl/nvme_loop_ctrl'. Not like nvme-pci, ->queues(and each element) won't be reallocated. So it is a nvme-pci specific issue. Thanks, Ming
