On 01/20/2012 07:43 PM, Hefty, Sean wrote:
However, what is is with user space setting type to IB_QPT_XRC_TGT?
I guess this could be solved by letting the kernel zero the memory
returned by ->ops.create_qp(pd, qp_init_attr). Btw, I didn't figure
out yet, how this translates at all in kernel space? Is this op
directly going to the device driver?
ops.create_qp basically ends up going into the kernel into
ib_uverbs_create_qp().
Thanks, I didn't find this.
But even if we are properly going to initialize the qp, what is
with user space mischievously trying to crash the system by
manipulating struct ib_qp *qp?
There's cleanup in uverbs that ignores the return value from
ib_destroy_qp(), basically because it shouldn't fail in those
circumstances. After calling ib_destroy_qp, uverbs will free some
internal structures that some of the callback handlers expect to
access. This leads to the crashes that you're seeing.
I think the problem is that your first patch is incomplete.
ib_uverbs_create_qp() will create a QP by either calling
ib_create_qp() or by calling the device directly (device->create_qp).
qp->usecnt needs to be initialized in both cases. Can you try this
modification to your original patch?
Thanks, this works either. But a question here, couldn't we just add the
"struct ib_udata *udata" as third parameter to ib_create_qp() and then
remove the if-condition in ib_uverbs_create_qp()?
if (cmd.qp_type == IB_QPT_XRC_TGT)
qp = ib_create_qp(pd, &attr);
else
qp = device->create_qp(pd, &attr, &udata);
So reduce this to
qp = ib_create_qp(pd, &attr, &attr);
Other callers of ib_create_qp() are not that many and would pass NULL
instead.
Cheers,
Bernd
From: Bernd Schubert<[email protected]>
From: Sean Hefty<[email protected]>
rdma/core: Fix kernel panic by always initializing qp->usecnt
We have just been investigating kernel panics related to
cq->ibcq.event_handler() completion calls.
Reason is that ib_destroy_qp() fails with -EBUSY. Further
investigation revealed qp->usecnt is not initialized. This counter
was introduced in linux-3.2 by commit
0e0ec7e0638ef48e0c661873dfcc8caccab984c6 and is only initialized for
IB_QPT_XRC_TGT, but also checked in ib_destroy_qp() for any qp type.
Signed-off-by: Bernd Schubert<[email protected]>
Signed-off-by: Sven Breuner<[email protected]>
Signed-off-by: Sean Hefty<[email protected]> ---
drivers/infiniband/core/uverbs_cmd.c | 1 +
drivers/infiniband/core/verbs.c | 2 +- 2 files changed, 2
insertions(+), 1 deletions(-)
diff --git a/drivers/infiniband/core/uverbs_cmd.c
b/drivers/infiniband/core/uverbs_cmd.c index e26193f..e47dbf1 100644
--- a/drivers/infiniband/core/uverbs_cmd.c +++
b/drivers/infiniband/core/uverbs_cmd.c @@ -1472,6 +1472,7 @@ ssize_t
ib_uverbs_create_qp(struct ib_uverbs_file *file, qp->event_handler =
attr.event_handler; qp->qp_context = attr.qp_context; qp->qp_type
= attr.qp_type; + atomic_set(&qp->usecnt, 0);
atomic_inc(&pd->usecnt); atomic_inc(&attr.send_cq->usecnt); if
(attr.recv_cq) diff --git a/drivers/infiniband/core/verbs.c
b/drivers/infiniband/core/verbs.c index 602b1bd..575b780 100644 ---
a/drivers/infiniband/core/verbs.c +++
b/drivers/infiniband/core/verbs.c @@ -421,6 +421,7 @@ struct ib_qp
*ib_create_qp(struct ib_pd *pd, qp->uobject = NULL; qp->qp_type
= qp_init_attr->qp_type;
+ atomic_set(&qp->usecnt, 0); if (qp_init_attr->qp_type ==
IB_QPT_XRC_TGT) { qp->event_handler = __ib_shared_qp_event_handler;
qp->qp_context = qp; @@ -430,7 +431,6 @@ struct ib_qp
*ib_create_qp(struct ib_pd *pd, qp->xrcd = qp_init_attr->xrcd;
atomic_inc(&qp_init_attr->xrcd->usecnt);
INIT_LIST_HEAD(&qp->open_list); -
atomic_set(&qp->usecnt, 0);
real_qp = qp; qp = __ib_open_qp(real_qp,
qp_init_attr->event_handler,
--
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