Commits
Eli Cohen committed e214a0fe2b3
IB/uverbs: Protect QP multicast list Userspace verbs multicast attach/detach operations on a QP are done while holding the rwsem of the QP for reading. That's not sufficient since a reader lock allows more than one reader to acquire the lock. However, multicast attach/detach does list manipulation that can corrupt the list if multiple threads run in parallel. Fix this by acquiring the rwsem as a writer to serialize attach/detach operations. Add idr_write_qp() and put_qp_write() to encapsulate this. This fixes oops seen when running applications that perform multicast joins/leaves. Reported by: Mike Dubman <miked@mellanox.com> Signed-off-by: Eli Cohen <eli@mellanox.com> Cc: <stable@kernel.org> Signed-off-by: Roland Dreier <roland@purestorage.com>