Hi Steve & Bernard, Thanks for the review comments. I will do those formating changes. Thanks, Krishna. On Wednesday, September 09/11/19, 2019 at 20:12:43 +0530, Steve Wise wrote: > On Wed, Sep 11, 2019 at 4:38 AM Bernard Metzler <BMT@xxxxxxxxxxxxxx> wrote: > > > > -----"Krishnamraju Eraparaju" <krishna2@xxxxxxxxxxx> wrote: ----- > > > > >To: "Sagi Grimberg" <sagi@xxxxxxxxxxx>, "Steve Wise" > > ><larrystevenwise@xxxxxxxxx>, "Bernard Metzler" <BMT@xxxxxxxxxxxxxx> > > >From: "Krishnamraju Eraparaju" <krishna2@xxxxxxxxxxx> > > >Date: 09/10/2019 09:22PM > > >Cc: "linux-rdma@xxxxxxxxxxxxxxx" <linux-rdma@xxxxxxxxxxxxxxx>, "Jason > > >Gunthorpe" <jgg@xxxxxxxx> > > >Subject: [EXTERNAL] Re: [PATCH v3] iwcm: don't hold the irq disabled > > >lock on iw_rem_ref > > > > > >Please review the below patch, I will resubmit this in patch-series > > >after review. > > >- As kput_ref handler(siw_free_qp) uses vfree, iwcm can't call > > > iw_rem_ref() with spinlocks held. Doing so can cause vfree() to > > >sleep > > > with irq disabled. > > > Two possible solutions: > > > 1)With spinlock acquired, take a copy of "cm_id_priv->qp" and > > >update > > > it to NULL. And after releasing lock use the copied qp pointer > > >for > > > rem_ref(). > > > 2)Replacing issue causing vmalloc()/vfree to kmalloc()/kfree in SIW > > > driver, may not be a ideal solution. > > > > > > Solution 2 may not be ideal as allocating huge contigous memory for > > > SQ & RQ doesn't look appropriate. > > > > > >- The structure "siw_base_qp" is getting freed in siw_destroy_qp(), > > >but > > > if cm_close_handler() holds the last reference, then siw_free_qp(), > > > via cm_close_handler(), tries to get already freed "siw_base_qp" > > >from > > > "ib_qp". > > > Hence, "siw_base_qp" should be freed at the end of siw_free_qp(). > > > > > > > Regarding the siw driver, I am fine with that proposed > > change. Delaying freeing the base_qp is OK. In fact, > > I'd expect the drivers soon are passing that responsibility > > to the rdma core anyway -- like for CQ/SRQ/PD/CTX objects, > > which are already allocated and freed up there. > > > > The iwcm changes look OK to me as well. > > > > Hey Krishna, Since the iwcm struct/state is still correctly being > manipulated under the lock, then I think it this patch correct. Test > the heck out of it. :) > > Steve.
