On 4/7/2016 11:31 AM, Leon Romanovsky wrote:
> On Thu, Apr 07, 2016 at 02:33:54AM +0300, Dan Jurgens wrote:
>
>> + if (sec->qp == sec->qp->real_qp) {
>> + /* The caller of this function holds the QP security
>> + * mutex so this list traversal is safe
>> + */
>
> Did the comment below pass checkpatch.pl?
It did.
>> + list_for_each_entry(shared_qp_sec,
>> + &sec->shared_qp_list,
>> + shared_qp_list) {
>
> Is this list always needed to be protected by lock?
> In general, I prefer to see lock/unlock operations near protected code.
> Otherwise, it is hard to follow all lock/unlock paths.
The mutex is required, and I'm not sure how to push it lower safely.
Consider the situation where a QP is being modified concurrently with an
open_shared_qp. Unless the lock is held the entire time for each
operation open_shared_qp could check permission using a ib_qp_security
struct in a partially modified state, i.e. there could be a mix of new
and old settings for the port/pkey index/alternate path. Shared QPs use
the port and pkey setting for the underlying real QP with the shared qp
q_security.
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