[PATCH 1/3] regulator: core: use system_freezable_wq for init complete work

[Joy Zou]

schedule_delayed_work() uses system_wq, which is non-freezable, allowing
regulator_init_complete_work to run concurrently with system suspend. This
work fires ~30s after boot to disable unused regulators via I2C. When it
races with PM suspend, the I2C adapter may already be suspended, triggering
a -ESHUTDOWN warning dump.

[   33.707233] pc : __i2c_transfer+0x36c/0x3c8
[   33.707240] lr : __i2c_transfer+0x36c/0x3c8
[   33.707246] sp : ffff80008239ba50
[   33.707249] x29: ffff80008239ba50 x28: 0000000000000001 x27: 0000000000000000
[   33.707259] x26: 0000000000000000 x25: 0000000000000001 x24: ffff0000c025c0e0
[   33.707268] x23: 0000000000000000 x22: ffff0000c025c0e1 x21: 0000000000000001
[   33.707277] x20: ffff80008239bae8 x19: ffff0000c0f54880 x18: fffffffffffeb320
[   33.707287] x17: 000000040044ffff x16: 0000000000000000 x15: ffff800082086fd8
[   33.707296] x14: 0000000000000000 x13: 0a6465646e657073 x12: 757320656c696877
[   33.707305] x11: 0000000000000058 x10: 0000000000000018 x9 : ffff800082087060
[   33.707314] x8 : 0000000000057fa8 x7 : 000000000000027d x6 : 0000000000000000
[   33.707323] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000ffffffff
[   33.707333] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000c0123480
[   33.707343] Call trace:
[   33.707346]  __i2c_transfer+0x36c/0x3c8 (P)
[   33.707356]  i2c_transfer+0x6c/0xf8
[   33.707364]  i2c_transfer_buffer_flags+0x5c/0xa0
[   33.707372]  regmap_i2c_write+0x20/0x60
[   33.707382]  _regmap_raw_write_impl+0x5cc/0x660
[   33.707389]  _regmap_bus_raw_write+0x60/0x80
[   33.707396]  _regmap_write+0x58/0xc0
[   33.707403]  _regmap_update_bits+0x11c/0x140
[   33.707409]  regmap_update_bits_base+0x54/0x80
[   33.707416]  regulator_disable_regmap+0x40/0x5c
[   33.707424]  _regulator_do_disable+0x94/0xbc
[   33.707435] CPU2 is up
[   33.707433]  regulator_late_cleanup+0xe0/0x1e8
[   33.707442]  class_for_each_device+0x104/0x13c
[   33.707450]  regulator_init_complete_work_function+0x54/0x80
[   33.707458]  process_one_work+0x150/0x290
[   33.707467]  worker_thread+0x180/0x2f4
[   33.707473]  kthread+0x12c/0x204
[   33.707484]  ret_from_fork+0x10/0x20
[   33.707493] ---[ end trace 0000000000000000 ]---

Switch to system_freezable_wq so the work is frozen before any device
is suspended, eliminating the race.

Fixes: 55576cf18537 ("regulator: Defer init completion for a while after late_initcall")
Signed-off-by: Joy Zou <joy.zou@xxxxxxxxxxx>
---
 drivers/regulator/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 1797929dfe56..d5d24a940f31 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -27,6 +27,7 @@
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 #include <linux/module.h>
+#include <linux/workqueue.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/regulator.h>
@@ -6882,8 +6883,9 @@ static int __init regulator_init_complete(void)
 	 * we'd only do this on systems that need it, and a kernel
 	 * command line option might be useful.
 	 */
-	schedule_delayed_work(&regulator_init_complete_work,
-			      msecs_to_jiffies(30000));
+	queue_delayed_work(system_freezable_wq,
+			   &regulator_init_complete_work,
+			   msecs_to_jiffies(30000));
 
 	return 0;
 }

-- 
2.34.1