net: rds: use maybe_get_net() when acquiring refcount on TCP sockets
Eric Dumazet is reporting addition on 0 problem at rds_tcp_tune(), for delayed works queued in rds_wq might be invoked after a net namespace's refcount already reached 0. Since rds_tcp_exit_net() from cleanup_net() calls flush_workqueue(rds_wq), it is guaranteed that we can instead use maybe_get_net() from delayed work functions until rds_tcp_exit_net() returns. Note that I'm not convinced that all works which might access a net namespace are already queued in rds_wq by the moment rds_tcp_exit_net() calls flush_workqueue(rds_wq). If some race is there, rds_tcp_exit_net() will fail to wait for work functions, and kmem_cache_free() could be called from net_free() before maybe_get_net() is called from rds_tcp_tune(). Reported-by: Eric Dumazet <edumazet@google.com> Fixes: 3a58f13a ("net: rds: acquire refcount on TCP sockets") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/41d09faf-bc78-1a87-dfd1-c6d1b5984b61@I-love.SAKURA.ne.jpSigned-off-by: Jakub Kicinski <kuba@kernel.org>
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