wifi: mt76: serialize scan-link teardown with dev->mutex

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The offchannel scan link is allocated in mt76_hw_scan() under
dev->mutex, but torn down without it: mt76_scan_complete() runs from
mt76_scan_work() on the mac80211 workqueue, or from mt76_abort_scan(),
and calls mt76_put_vif_phy_link(), whose vif_link_remove clears the
per-phy omac_mask and the device-wide vif_mask/mld_idx_mask with plain
read-modify-write. A vif link add or remove for another interface,
running concurrently under dev->mutex, can interleave with these
unlocked writes and lose an update: a cleared bit belonging to a live
link gets handed out again (two links sharing an omac/bss/wcid index,
breaking own-MAC unicast RX for the first one), or a freed bit stays
set until reboot and eventually exhausts the index space.

Take dev->mutex around the scan completion, mirroring the ROC teardown
in mt76_roc_complete_work()/mt76_abort_roc(), and switch the channel
restore to __mt76_set_channel() since the caller now holds the lock.
mt76_abort_scan() keeps cancelling the scan work before taking the
mutex, so the work-vs-abort ordering is unchanged.

Signed-off-by: Chad Monroe <chad@monroe.io>
Link: https://patch.msgid.link/20260724124813.3961474-28-nbd@nbd.name
Signed-off-by: Felix Fietkau <nbd@nbd.name>

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Chad Monroe 2026-07-24 12:48:12 +00:00 • committed by Felix Fietkau

parent 6ff1c217a0

commit 4c3cf4a8b1

1 changed files with 8 additions and 1 deletions

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9

drivers/net/wireless/mediatek/mt76/scan.c

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