Messages in this thread | | | Date | Tue, 13 Jul 2021 14:05:33 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH] s390/vfio-ap: do not open code locks for VFIO_GROUP_NOTIFY_SET_KVM notification |
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On Tue, Jul 13, 2021 at 06:45:17PM +0200, Halil Pasic wrote:
> Jason may give it another try to convince us that 0cc00c8d4050 only > silenced lockdep, but vfio_ap remained prone to deadlocks. To my best > knowledge using condition variable and a mutex is one of the well known > ways to implement an rwlock.
The well known pattern is to use a rwsem.
This: wait_event_cmd(matrix_mdev->wait_for_kvm, !matrix_mdev->kvm_busy, mutex_unlock(&matrix_dev->lock), mutex_lock(&matrix_dev->lock));
Is not really a rwsem, and is invsible to lockdep.
Jason
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