vhost internals involves multiple locks to protect data access by multiple threads.
This series is a try at using clang thread safety checks [1] to catch issues during compilation: spinlock and rwlock are wrapped into vhost types and annotations are put all over the code. Patch 1 is a fix from Maxime that I had to take in the series so that the CI won't fail. Patch 2 annotates existing manipulations of the access_lock vq lock. It does the minimal stuff, more annotations are used/introduced later in the series. Patch 4 is an example of extending the work by annotating the async field. This patch raised the issues fixed in patch 3. Patch 5 further extends this by annotating rwlocks used in IOTLB. This raised two suspicious call sites (in vdpa and vhost_crypto code, see added FIXME). Because of a limitation in the check, the IOTLB lock is changed to be always taken. I don't expect a big impact, but this needs a confirmation. This is still a work in progress. Those annotations are quite heavy to maintain because the full path of code must be annotated, but I think it would be worth using. 1: https://clang.llvm.org/docs/ThreadSafetyAnalysis.html -- David Marchand David Marchand (4): vhost: annotate virtqueue access lock vhost: fix async access vhost: annotate async locking requirement vhost: annotate IOTLB locks Maxime Coquelin (1): vhost: fix missing virtqueue lock protection lib/vhost/iotlb.c | 36 ++++----- lib/vhost/iotlb.h | 24 ------ lib/vhost/meson.build | 3 + lib/vhost/vdpa.c | 1 + lib/vhost/vhost.c | 85 ++++++++++---------- lib/vhost/vhost.h | 169 +++++++++++++++++++++++++++++++++++---- lib/vhost/vhost_crypto.c | 7 ++ lib/vhost/vhost_user.c | 32 +++++--- lib/vhost/virtio_net.c | 96 ++++++++++++++++------ 9 files changed, 320 insertions(+), 133 deletions(-) -- 2.23.0
