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When Devres::drop() wins the is_available swap and the > devres callback loses, the callback returns to devres_release_all() > without waiting. This means device unbinding can complete while > Devres::drop() is still executing drop_in_place() on another CPU, which > is a problem if T's destructor accesses device state. >=20 > Make the synchronization bidirectional. Whichever side performs > drop_in_place() signals the Completion, and the other side waits. >=20 > This does not reintroduce the nested Devres deadlock fixed by commit > ba268514ea14 ("rust: devres: fix race condition due to nesting"), > because that deadlock was caused by drop waiting for the release > callback to return (the old 'devm' Completion). Here, both sides only > wait for drop_in_place() to finish, which completes within the current > call chain. The Arc> keeps the Inner allocation alive > independently. >=20 > Cc: stable@vger.kernel.org > Fixes: ba268514ea14 ("rust: devres: fix race condition due to nesting") > Signed-off-by: Danilo Krummrich Reviewed-by: Gary Guo > --- > rust/kernel/devres.rs | 7 +++++++ > 1 file changed, 7 insertions(+)