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.
