On Sat, Nov 10, 2018 at 03:52:13PM -0800, Chenbo Feng wrote:
From: Daniel Colascione dancol@google.com
commit 1ae80cf31938c8f77c37a29bbe29e7f1cd492be8 upstream.
The map-in-map frequently serves as a mechanism for atomic snapshotting of state that a BPF program might record. The current implementation is dangerous to use in this way, however, since userspace has no way of knowing when all programs that might have retrieved the "old" value of the map may have completed.
This change ensures that map update operations on map-in-map map types always wait for all references to the old map to drop before returning to userspace.
Signed-off-by: Daniel Colascione dancol@google.com Reviewed-by: Joel Fernandes (Google) joel@joelfernandes.org Signed-off-by: Alexei Starovoitov ast@kernel.org
[fengc@google.com: 4.19 clean cherry-picks, no modification] Signed-off-by: Chenbo Feng fengc@google.com
Greg has queued all 3 patches in this series to their respective trees, but I didn't see a mail from him. Thank you for the backports.
-- Thanks, Sasha