Jarno Rajahalme wrote:
Daniele, Martino,
Thank you for the contribution, and sorry that it has taken so long for me to
get to the review!
[...]
Dear all,
we are working on Jarno revision, and we will provide shortly a revised patch.
In the meantime, I would like to ask for advice on an issue we have encountered.
In RSTP, there are some cases in which the reception of an incoming BPDU
triggers the the transmission of one or more BPDUs.
It seems that the approach we are following at the moment could not allow such,
as a deadlock on the xlate_rwlock mutex is triggered.
In particular:
* The reception of a BPDU triggers the execution of xlate_actions__()
[ofproto/ofproto-dpif-xlate.c] which takes a lock on xlate_rwlock.
* The processing of such BPDU inside lib/rstp* components triggers the
following calls:
** rstp_send_bpdu() [lib/rstp-state-machines.c]
** rstp_send_bpdu_cb() [lib/ofproto/ofproto-dpif.c]
** ofproto_dpif_send_packet() [lib/ofproto/ofproto-dpif.c]
** xlate_send_packet() [lib/ofproto-dpif.xlate.c]
** xlate_send_packet() tries to acquire a lock on xlate_rwlock, resulting in a
deadlock.
I am not familiar with the internals of ovs locking mechanisms, so, I am not
sure how to proceed...
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