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Recently Dough Ledford reported a deadlock happening
between ocrdma-load sequence and NetworkManager service
issuing "open" on be2net interface.
The deadlock happens when any be2net hook (e.g. open/close) is called
in parallel to insmod ocrdma.ko.
A. be2net is sending administrative open/close event to ocrdma holding
device_list_mutex. It does this from ndo_open/ndo_stop hooks of be2net.
So sequence of locks is rtnl_lock---> device_list lock
B. When new ocrdma roce device gets registered, infiniband stack now
takes rtnl_lock in ib_register_device() in GID initialization routines.
So sequence of locks in this path is device_list lock ---> rtnl_lock.
This improper locking sequence causes deadlock.
With this patch we stop using administrative open and close events
injected by be2net driver. These events were used to dispatch PORT_ACTIVE
and PORT_ERROR events to the IB-stack. This patch implements a logic
to receive async-link-events generated from CNA whenever link-state-change
is detected. Now on, these async-events will be used to dispatch
PORT_ACTIVE and PORT_ERROR events to IB-stack.
Depending on async-events from CNA removes the need to hold device-list-mutex
and thus breaks the busy-wait scenario.
Reported-by: Doug Ledford <dledford@redhat.com>
CC: Sathya Perla <sathya.perla@avagotech.com>
Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@avagotech.com>
Signed-off-by: Selvin Xavier <selvin.xavier@avagotech.com>
Signed-off-by: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
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