On Mon, Nov 26, 2018 at 11:59:15AM +0200, Gal Pressman wrote: > On 26-Nov-18 09:48, Leon Romanovsky wrote: > > From: Parav Pandit <parav@xxxxxxxxxxxx> > > > > Describe core documentation for ib_device_mutex, ib_list_rwsem, > > net_rwsem and compat_dev_sem. > > > > Signed-off-by: Parav Pandit <parav@xxxxxxxxxxxx> > > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx> > > --- > > Documentation/infiniband/core_devices.txt | 73 ++++++++++++++++++++++- > > 1 file changed, 70 insertions(+), 3 deletions(-) > > > > diff --git a/Documentation/infiniband/core_devices.txt b/Documentation/infiniband/core_devices.txt > > index ff28def49ff4..fd98b27dd3d9 100644 > > --- a/Documentation/infiniband/core_devices.txt > > +++ b/Documentation/infiniband/core_devices.txt > > @@ -51,7 +51,7 @@ All ib_core_device(s) points to one owner ib_device using driver_data. > > | | | | > > | | | | > > | +----------+ | (init_net) > > - | | ib_device > > + | *net | ib_device > > | *owner-------------------------+------>+--------------------+<--+ > > +--------------+ | | | | > > | | ib_core_device | | > > @@ -63,12 +63,12 @@ All ib_core_device(s) points to one owner ib_device using driver_data. > > +--------------+ | | | | | | | | > > | | | | | | | | | | > > | device | | | | +----------+ | | | > > - | +----------+ | | | | | | | > > + | +----------+ | | | | *net | | | > > | | | | | | | *owner--------------+ > > | | | | | | +--------------+ | > > | | | | | +--------------------+ > > | +----------+ | | > > - | | | > > + | *net | | > > | *owner------------------------+ > > +--------------+ > > > > @@ -96,6 +96,73 @@ ib_device > > | | | | | | > > | | +----------+ | | > > | | | | > > +| | *net | | > > | | *owner | | > > | +--------------+ | > > +--------------------+ > > + > > +2.3 locking scheme > > +-------------------------------------------------------- > > +There are three locks involved to provide synchronization between four > > +operations. > > +These four operations are > > +(a) device addition using ib_register_device() > > +(b) device removal using ib_unregister_device() > > +(c) net namespace addition using _init_net() notifier > > +(d) net namespace removal using _exit_net() notifier > > + > > +ib_register_device() and ib_unregister_device() work on all net namespaces > > +to add/remove compat devices. Therefore, they need to hold net_rwsem read > > +lock so that net namespace doesn't disappear while this compat devices > > +add/remove occurs. > > + > > +Multiple rdma devices of same or different vendors can be enumerated in > > +parallel trying to add/remove compat devices for a net namespace. > > +Therefore, protect compat device list operations using compat_rwsem read/write > > +semaphore. > > +Even though multiple device enumration is currently guarded using > > Hi Leon, Thanks Gal, I'm resending fixed version now.
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