block, bfq: check and switch back to interactive wr also on queue split
As already explained in the message of commit "block, bfq: fix wrong init of saved start time for weight raising", if a soft real-time weight-raising period happens to be nested in a larger interactive weight-raising period, then BFQ restores the interactive weight raising at the end of the soft real-time weight raising. In particular, BFQ checks whether the latter has ended only on request dispatches. Unfortunately, the above scheme fails to restore interactive weight raising in the following corner case: if a bfq_queue, say Q, 1) Is merged with another bfq_queue while it is in a nested soft real-time weight-raising period. The weight-raising state of Q is then saved, and not considered any longer until a split occurs. 2) Is split from the other bfq_queue(s) at a time instant when its soft real-time weight raising is already finished. On the split, while resuming the previous, soft real-time weight-raised state of the bfq_queue Q, BFQ checks whether the current soft real-time weight-raising period is actually over. If so, BFQ switches weight raising off for Q, *without* checking whether the soft real-time period was actually nested in a non-yet-finished interactive weight-raising period. This commit addresses this issue by adding the above missing check in bfq_queue splits, and restoring interactive weight raising if needed. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Angelo Ruocco <angeloruocco90@gmail.com> Tested-by: Mirko Montanari <mirkomontanari91@gmail.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Tested-by: Lee Tibbert <lee.tibbert@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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