Multicast attach/detach operations on a QP are carried under the readers'/writers' lock of the QP. Such protection is not sufficient since a reader's lock allows more than one reader to acquire the lock. However, list manipulation implies write operations on the list variable. Acquire the lock as a writer to serialize attach/detach operations. Add idr_write_qp() and put_qp_write(). We have hit kernel oops when running applications that perform multicast joins/leaves. This patch solved the issue.
Reported by: Mike Dubman <mi...@mellanox.com> Signed-off-by: Eli Cohen <e...@mellanox.com> --- Changes from previous version: Avoid the spinlock and serialize the entire operation by taking the lock as a writer. drivers/infiniband/core/uverbs_cmd.c | 21 +++++++++++++++++---- 1 files changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c index 254f164..e3db8ef 100644 --- a/drivers/infiniband/core/uverbs_cmd.c +++ b/drivers/infiniband/core/uverbs_cmd.c @@ -241,11 +241,24 @@ static struct ib_qp *idr_read_qp(int qp_handle, struct ib_ucontext *context) return idr_read_obj(&ib_uverbs_qp_idr, qp_handle, context, 0); } +static struct ib_qp *idr_write_qp(int qp_handle, struct ib_ucontext *context) +{ + struct ib_uobject *uobj; + + uobj = idr_write_uobj(&ib_uverbs_qp_idr, qp_handle, context); + return uobj ? uobj->object : NULL; +} + static void put_qp_read(struct ib_qp *qp) { put_uobj_read(qp->uobject); } +static void put_qp_write(struct ib_qp *qp) +{ + put_uobj_write(qp->uobject); +} + static struct ib_srq *idr_read_srq(int srq_handle, struct ib_ucontext *context) { return idr_read_obj(&ib_uverbs_srq_idr, srq_handle, context, 0); @@ -2375,7 +2388,7 @@ ssize_t ib_uverbs_attach_mcast(struct ib_uverbs_file *file, if (copy_from_user(&cmd, buf, sizeof cmd)) return -EFAULT; - qp = idr_read_qp(cmd.qp_handle, file->ucontext); + qp = idr_write_qp(cmd.qp_handle, file->ucontext); if (!qp) return -EINVAL; @@ -2404,7 +2417,7 @@ ssize_t ib_uverbs_attach_mcast(struct ib_uverbs_file *file, kfree(mcast); out_put: - put_qp_read(qp); + put_qp_write(qp); return ret ? ret : in_len; } @@ -2422,7 +2435,7 @@ ssize_t ib_uverbs_detach_mcast(struct ib_uverbs_file *file, if (copy_from_user(&cmd, buf, sizeof cmd)) return -EFAULT; - qp = idr_read_qp(cmd.qp_handle, file->ucontext); + qp = idr_write_qp(cmd.qp_handle, file->ucontext); if (!qp) return -EINVAL; @@ -2441,7 +2454,7 @@ ssize_t ib_uverbs_detach_mcast(struct ib_uverbs_file *file, } out_put: - put_qp_read(qp); + put_qp_write(qp); return ret ? ret : in_len; } -- 1.7.8 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html