On 2019/9/11 21:17, Liuyixian (Eason) wrote: > > > On 2019/9/10 15:52, Leon Romanovsky wrote: >> On Tue, Sep 10, 2019 at 02:40:20PM +0800, Liuyixian (Eason) wrote: >>> >>> >>> On 2019/9/8 16:03, Leon Romanovsky wrote: >>>> On Thu, Sep 05, 2019 at 08:31:11PM +0800, Weihang Li wrote: >>>>> From: Yixian Liu <liuyixian@xxxxxxxxxx> >>>>> >>>>> Hip08 has the feature flush cqe, which help to flush wqe in workqueue >>>>> (sq and rq) when error happened by transmitting producer index with >>>>> mailbox to hardware. Flush cqe is emplemented in post send and recv >>>>> verbs. However, under NVMe cases, these verbs will be called under >>>>> softirq context, and it will lead to following calltrace with >>>>> current driver as mailbox used by flush cqe can go to sleep. >>>>> >>>>> This patch solves this problem by using workqueue to do flush cqe, >>>> >>>> Unbelievable, almost every bug in this driver is solved by introducing >>>> workqueue. You should fix "sleep in flush path" issue and not by adding >>>> new workqueue. >>>> >>> Hi Leon, >>> >>> Thanks for the comment. >>> Up to now, for hip08, only one place use workqueue in hns_roce_hw_v2.c >>> where for irq prints. >> >> Thanks to our lack of desire to add more workqueues and previous patches >> which removed extra workqueues from the driver. >> > Thanks, I see. > >>> >>> The solution for flush cqe in this patch is as follow: >>> While flush cqe should be implement, the driver should modify qp to error state >>> through mailbox with the newest product index of sq and rq, the hardware then >>> can flush all outstanding wqes in sq and rq. >>> >>> That's the whole mechanism of flush cqe, also is the flush path. We can't >>> change neither mailbox sleep attribute or flush cqe occurred in post send/recv. >>> To avoid the calltrace of flush cqe in post verbs under NVMe softirq, >>> use workqueue for flush cqe seems reasonable. >>> >>> As far as I know, there is no other alternative solution for this situation. >>> I will be very grateful if you reminder me more information. >> >> ib_drain_rq/ib_drain_sq/ib_drain_qp???? >> > Hi Leon, > > I think these interfaces are designed for application to check that all wqes > have been processed by hardware, so called drain or flush. However, it is not > the same as the flush in this patch. The solution in this patch is used > to help the hardware generate flush cqes for outstanding wqes while qp error. > Hi Leon, What's your opinion about above? Do you have any further comments? Thanks. >>> >>> Thanks >>> >>>> _______________________________________________ >>>> Linuxarm mailing list >>>> Linuxarm@xxxxxxxxxx >>>> http://hulk.huawei.com/mailman/listinfo/linuxarm >>>> >>>> >>> >> >> . >> > > _______________________________________________ > Linuxarm mailing list > Linuxarm@xxxxxxxxxx > http://hulk.huawei.com/mailman/listinfo/linuxarm > > . >
