[PATCH v3 7/7] efi/runtime-wrappers: retire the worker if a wedged call ever returns

[Breno Leitao]

When __efi_queue_work() times out it disables runtime services and
returns, but the kworker is still blocked inside firmware. If the
firmware eventually unblocks, efi_call_rts() would run its tail on an
efi_rts_work that the timed-out caller has long abandoned: signalling a
stale completion and clearing efi_runtime_lock_owner that may by then
belong to another caller.

If runtime services have been disabled by the time the call returns,
park the worker with efi_rts_park_worker() instead, so it never touches
efi_rts_work again or returns to the workqueue.

Suggested-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
---
 drivers/firmware/efi/runtime-wrappers.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index 2b0a7caf90944..591a725b10613 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -336,6 +336,9 @@ static void __nocfi efi_call_rts(struct work_struct *work)
 	efi_call_virt_check_flags(flags, efi_rts_work.caller);
 	arch_efi_call_virt_teardown();
 
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		efi_rts_park_worker();
+
 	efi_rts_work.status = status;
 	complete(&efi_rts_work.efi_rts_comp);
 	efi_runtime_lock_owner = NULL;

-- 
2.53.0-Meta