linux-kernel - Re: [PATCH] gpio: sprd: Change sprd_gpio lock to raw_spin

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Message-ID: <20260126095024.ZEEwNmlk@linutronix.de>
Date: Mon, 26 Jan 2026 10:50:24 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Xuewen Yan <xuewen.yan@...soc.com>
Cc: linusw@...nel.org, brgl@...nel.org, orsonzhai@...il.com,
	baolin.wang@...ux.alibaba.com, zhang.lyra@...il.com,
	clrkwllms@...nel.org, rostedt@...dmis.org,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-rt-devel@...ts.linux.dev, ke.wang@...soc.com,
	wenhua.lin@...soc.com, xuewen.yan94@...il.com
Subject: Re: [PATCH] gpio: sprd: Change sprd_gpio lock to raw_spin_lock

On 2026-01-26 17:42:09 [+0800], Xuewen Yan wrote:
> There was a lockdep warning in sprd_gpio:
> 
> [    6.258269][T329@C6] [ BUG: Invalid wait context ]
> [    6.258270][T329@C6] 6.18.0-android17-0-g30527ad7aaae-ab00009-4k #1 Tainted: G        W  OE
> [    6.258272][T329@C6] -----------------------------
> [    6.258273][T329@C6] modprobe/329 is trying to lock:
> [    6.258275][T329@C6] ffffff8081c91690 (&sprd_gpio->lock){....}-{3:3}, at: sprd_gpio_irq_unmask+0x4c/0xa4 [gpio_sprd]
> [    6.258282][T329@C6] other info that might help us debug this:
> [    6.258283][T329@C6] context-{5:5}
> [    6.258285][T329@C6] 3 locks held by modprobe/329:
> [    6.258286][T329@C6]  #0: ffffff808baca108 (&dev->mutex){....}-{4:4}, at: __driver_attach+0xc4/0x204
> [    6.258295][T329@C6]  #1: ffffff80965e7240 (request_class#4){+.+.}-{4:4}, at: __setup_irq+0x1cc/0x82c
> [    6.258304][T329@C6]  #2: ffffff80965e70c8 (lock_class#4){....}-{2:2}, at: __setup_irq+0x21c/0x82c
> [    6.258313][T329@C6] stack backtrace:
> [    6.258314][T329@C6] CPU: 6 UID: 0 PID: 329 Comm: modprobe Tainted: G        W  OE       6.18.0-android17-0-g30527ad7aaae-ab00009-4k #1 PREEMPT  3ad5b0f45741a16e5838da790706e16ceb6717df
> [    6.258316][T329@C6] Tainted: [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
> [    6.258317][T329@C6] Hardware name: Unisoc UMS9632-base Board (DT)
> [    6.258318][T329@C6] Call trace:
> [    6.258318][T329@C6]  show_stack+0x20/0x30 (C)
> [    6.258321][T329@C6]  __dump_stack+0x28/0x3c
> [    6.258324][T329@C6]  dump_stack_lvl+0xac/0xf0
> [    6.258326][T329@C6]  dump_stack+0x18/0x3c
> [    6.258329][T329@C6]  __lock_acquire+0x824/0x2c28
> [    6.258331][T329@C6]  lock_acquire+0x148/0x2cc
> [    6.258333][T329@C6]  _raw_spin_lock_irqsave+0x6c/0xb4
> [    6.258334][T329@C6]  sprd_gpio_irq_unmask+0x4c/0xa4 [gpio_sprd 814535e93c6d8e0853c45c02eab0fa88a9da6487]
> [    6.258337][T329@C6]  irq_startup+0x238/0x350
> [    6.258340][T329@C6]  __setup_irq+0x504/0x82c
> [    6.258342][T329@C6]  request_threaded_irq+0x118/0x184
> [    6.258344][T329@C6]  devm_request_threaded_irq+0x94/0x120
> [    6.258347][T329@C6]  sc8546_init_irq+0x114/0x170 [sc8546_charger 223586ccafc27439f7db4f95b0c8e6e882349a99]
> [    6.258352][T329@C6]  sc8546_charger_probe+0x53c/0x5a0 [sc8546_charger 223586ccafc27439f7db4f95b0c8e6e882349a99]
> [    6.258358][T329@C6]  i2c_device_probe+0x2c8/0x350
> [    6.258361][T329@C6]  really_probe+0x1a8/0x46c
> [    6.258363][T329@C6]  __driver_probe_device+0xa4/0x10c
> [    6.258366][T329@C6]  driver_probe_device+0x44/0x1b4
> [    6.258369][T329@C6]  __driver_attach+0xd0/0x204
> [    6.258371][T329@C6]  bus_for_each_dev+0x10c/0x168
> [    6.258373][T329@C6]  driver_attach+0x2c/0x3c
> [    6.258376][T329@C6]  bus_add_driver+0x154/0x29c
> [    6.258378][T329@C6]  driver_register+0x70/0x10c
> [    6.258381][T329@C6]  i2c_register_driver+0x48/0xc8
> [    6.258384][T329@C6]  init_module+0x28/0xfd8 [sc8546_charger 223586ccafc27439f7db4f95b0c8e6e882349a99]
> [    6.258389][T329@C6]  do_one_initcall+0x128/0x42c
> [    6.258392][T329@C6]  do_init_module+0x60/0x254
> [    6.258395][T329@C6]  load_module+0x1054/0x1220
> [    6.258397][T329@C6]  __arm64_sys_finit_module+0x240/0x35c
> [    6.258400][T329@C6]  invoke_syscall+0x60/0xec
> [    6.258402][T329@C6]  el0_svc_common+0xb0/0xe4
> [    6.258405][T329@C6]  do_el0_svc+0x24/0x30
> [    6.258407][T329@C6]  el0_svc+0x54/0x1c4
> [    6.258409][T329@C6]  el0t_64_sync_handler+0x68/0xdc
> [    6.258411][T329@C6]  el0t_64_sync+0x1c4/0x1c8

This could be reduced to "BUG: Invalid wait context". The other bits
provide to added value.

> This is because the spin_lock would change to rt_mutex in PREEMPT_RT,
> however the sprd_gpio->lock would use in hard-irq, this is unsafe.
> 
> So change the spin_lock to raw_spin_lock to use the spinlock

spinlock_t to raw_spinlock_t

> in hard-irq.
> 
> Signed-off-by: Xuewen Yan <xuewen.yan@...soc.com>

Other than that
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

Sebastian