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lane_used_bandwidth is used to store the used bandwidth for each lane. When we restore the bus->params, the lane_used_bandwidth value will not be restored in current code. Move it to sdw_bus_params to fix the issue. Fixes: 366fd59 ("soundwire: generic_bandwidth_allocation: add lane in sdw_group_params") Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
When preparing a multi-link aggregation stream, a failure on a subsequent link during _sdw_prepare_stream() causes the stream preparation to fail. However, the bandwidth allocated on the preceding successful links is never released, causing a cumulative bandwidth leak. Fix this by saving a snapshot of each bus's parameters before making any modifications. In case of failure, we iterate through the stream's master list and restore each bus to its original parameter state, ensuring an atomic rollback and preventing any bandwidth leaks. Signed-off-by: David Lin <david.lin@intel.com>
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October 13, 2026 05:07
bardliao
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🟡 Changes recommended
Rollback leaves port-lane state inconsistent and can desynchronize software bank state from hardware.
1 open finding
What changed in this PR
Fixes SoundWire bandwidth accounting rollback when multi-link stream preparation fails.
Changes:
- Snapshots and restores parameters for every master bus.
- Moves per-lane bandwidth accounting into
sdw_bus_params. - Updates allocation and depreparation paths for the relocated accounting.
| File | Description |
|---|---|
include/linux/soundwire/sdw.h |
Relocates per-lane bandwidth state. |
drivers/soundwire/stream.c |
Adds multi-bus rollback handling. |
drivers/soundwire/generic_bandwidth_allocation.c |
Uses relocated lane accounting. |
drivers/soundwire/bus.h |
Adds per-master parameter snapshots. |
🧠 Review effort: Balanced
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davidlin923
approved these changes
Oct 13, 2026
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When preparing a multi-link aggregation stream, a failure on a subsequent link during _sdw_prepare_stream() causes the stream preparation to fail. However, the bandwidth allocated on the preceding successful links is never released, causing a cumulative bandwidth leak.
Fix this by restoring the parameters for all buses.