PROVE_LOCKING reports:
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
kworker/u16:1 is trying to acquire:
&hw_priv->tx_loop.pending_record_lock at bes2600_queue_clear+0x80
and this task is already holding:
&queue->lock at bes2600_queue_clear+0x60
which would create a new lock dependency:
(&queue->lock){+.-.} -> (&hw_priv->tx_loop.pending_record_lock){+.+.}
but this new dependency connects a SOFTIRQ-irq-safe lock:
(&queue->lock){+.-.}
... which became SOFTIRQ-irq-safe at:
bes2600_tx -> ieee80211_handle_wake_tx_queue -> tasklet_action
to a SOFTIRQ-irq-unsafe lock:
(&hw_priv->tx_loop.pending_record_lock){+.+.}
... which became SOFTIRQ-irq-unsafe at:
bes2600_queue_get_skb -> bes2600_join_work -> process_one_work
queue->lock is taken consistently with spin_lock_bh() at 22 sites;
the nested acquisition of pending_record_lock at queue.c:289 (inside
the outer queue->lock_bh held at line 285) had it implicitly BH-safe
via the outer scope. But pending_record_lock is ALSO taken from
non-BH-disabled contexts:
bes2600_queue_get_skb (queue.c:832) — process context via
bes2600_join_work (workqueue), no outer queue->lock held
bes2600_tx_loop_item_pending_check (tx_loop.c:112)
— TX-loop context, no outer
queue->lock held
When CPU0 holds pending_record_lock from one of those non-BH paths
and a softirq fires that wants queue->lock, and CPU1 in softirq has
queue->lock and is about to acquire pending_record_lock — classic AB-BA
SOFTIRQ deadlock.
The fix is the conservative one: take pending_record_lock with _bh()
at every site that's not already inside a queue->lock_bh-held scope.
That makes the lock consistently SOFTIRQ-safe, eliminating the
inversion. queue.c:289/295 stays as plain spin_lock because BH is
already disabled by the outer queue->lock_bh acquired at queue.c:285.
Five sites converted:
bes2600/queue.c:832 -- spin_lock -> spin_lock_bh
bes2600/queue.c:839 -- spin_unlock -> spin_unlock_bh
bes2600/queue.c:844 -- spin_unlock -> spin_unlock_bh
bes2600/tx_loop.c:112 -- spin_lock -> spin_lock_bh
bes2600/tx_loop.c:114 -- spin_unlock -> spin_unlock_bh
Contract:
- Documentation/locking/locktypes.rst spelling: spin_lock_bh() is
the canonical way to make a non-IRQ spinlock safe against
softirq preemption that might re-enter the same lock.
- Same shape as queue->lock in this driver and as is_drv->lock
in the cw1200 ancestor.
Closes: besser#18
Fixes: <bes2600 base import>
Signed-off-by: Markus Fritsche <fritsche.markus@gmail.com>
The bes2600 driver is a fork of the upstream cw1200 driver
(drivers/net/wireless/st/cw1200/, ST-Ericsson, Dmitry Tarnyagin
2010-2011). The fork's file headers have three GPL-compliance issues:
1. NO SPDX-License-Identifier on any of 48 source files (cw1200
mainline has them on all 25). kernel.org-mandated since 2017.
2. Original "Copyright (c) 2010, ST-Ericsson" lines stripped from
all files inherited from cw1200, replaced with
"Copyright (c) 2010, Bestechnic" — factually impossible
(Bestechnic did not author the 2010 work) and a GPL-2.0 §1
attribution-preservation violation.
3. The "GPL version 2 as published by the Free Software Foundation"
boilerplate paragraph is redundant alongside SPDX and is the
legacy form modern kernel sources have replaced.
This patch corrects all three for the 48 .c/.h files in bes2600/:
- Adds `// SPDX-License-Identifier: GPL-2.0-only` (or `/* ... */`
for headers) as line 1 of every file.
- Restores `Copyright (c) 2010, ST-Ericsson` + `Author: Dmitry
Tarnyagin <dmitry.tarnyagin@lockless.no>` as the FIRST copyright
chain entry on all 22 files derived from cw1200 (bh.{c,h},
debug.{c,h}, fwio.{c,h}, hwio.{c,h}, main.c, pm.{c,h},
queue.{c,h}, scan.{c,h}, sta.{c,h}, txrx.{c,h}, wsm.{c,h}).
- Keeps `Copyright (c) 2022, Bestechnic (Beijing) Co., Ltd.` as
the SECOND chain entry where Bestechnic genuinely contributed.
- Notes "Derived from cw1200_sdio.c" + ST-Ericsson copyright on
bes2600_sdio.c (heavy derivation, not a literal rename).
- Notes "Replaces hwbus.h from cw1200/" + ST-Ericsson copyright
on sbus.h.
- Preserves the prism54/islsm authorship chain on main.c and
bes2600.h (Michael Wu 2006 + Jean-Baptiste Note 2004-2006).
- Drops the GPL-2.0 boilerplate paragraph in favour of SPDX.
No code changes — only file-header comment blocks. Module build is
unaffected (verified by header-only diff scope).
This is a prerequisite for any kernel.org submission attempt. The
existing MODULE_LICENSE("GPL") + MODULE_AUTHOR(Tarnyagin@stericsson.com)
declarations were already present and are unchanged here; the
mismatch between MODULE_AUTHOR and the (since-corrected) per-file
copyrights is now resolved.
test0r
Julian