From mboxrd@z Thu Jan 1 00:00:00 1970 From: dledford@redhat.com (Doug Ledford) Date: Tue, 02 Aug 2016 13:24:16 -0400 Subject: [PATCH v2 0/2] iwarp device removal deadlock fixes In-Reply-To: References: Message-ID: <1470158656.18081.17.camel@redhat.com> On Fri, 2016-07-29@13:36 -0700, Steve Wise wrote: > This series fixes the deadlock issue discovered while testing > nvmf/rdma > handling rdma device removal events from the rdma_cm.??For a > discussion > of the deadlock that can happen, see > > http://lists.infradead.org/pipermail/linux-nvme/2016-July/005440.html > . > > For my description of the deadlock itself, see this post in the above > thread: > > http://lists.infradead.org/pipermail/linux-nvme/2016-July/005465.html > > In a nutshell, iw_cxgb4 and the iw_cm block during qp/cm_id > destruction > until all references are removed.??This combined with the iwarp CM > passing > disconnect events up to the rdma_cm during disconnect and/or qp/cm_id > destruction > leads to a deadlock. > > My proposed solution is to remove the need for iw_cxgb4 and iw_cm to > block during object destruction for the refnts to reach 0, but rather > to > let the freeing of the object memory be deferred when the last deref > is > done, which is SOP in the much of the linux kernel. This allows all > the > qps/cm_ids to be destroyed without blocking, and all the object > memory > freeing ends up happinging when the application's device_remove event > handler function returns to the rdma_cm. > > This series is needed along with Sagi's fixes from: > https://www.spinics.net/lists/linux-rdma/msg38715.html > > Hey Faisal, it would be great to get some review/test tags from Intel > on the iw_cm change.??Thanks! > > Changes since v1: > > - reworded commit text for the iw_cm patch > > - added a iw_cm_id flag to drop pending events when the cm_id has > been marked for destruction. > > --- > > Steve Wise (2): > ? iw_cxgb4: don't block in destroy_qp awaiting the last deref > ? iw_cm: free cm_id resources on the last deref > > ?drivers/infiniband/core/iwcm.c?????????| 54 +++++++++++------------- > ---------- > ?drivers/infiniband/core/iwcm.h?????????|??2 +- > ?drivers/infiniband/hw/cxgb4/iw_cxgb4.h |??2 +- > ?drivers/infiniband/hw/cxgb4/qp.c???????| 21 ++++++++----- > ?4 files changed, 33 insertions(+), 46 deletions(-) > Series applied, thanks. -- Doug Ledford GPG KeyID: 0E572FDD -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: This is a digitally signed message part URL: