Bug 33759

Summary:	49bluetooth hook needs to wait for btusb module to get unused
Product:	pm-utils	Reporter:	Martin Pitt <martin.pitt>
Component:	General	Assignee:	Richard Hughes <richard>
Status:	RESOLVED WONTFIX	QA Contact:
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	patch against git head

Description Martin Pitt 2011-01-31 06:12:10 UTC

(Original bug at https://launchpad.net/bugs/698331)

The 49bluetooth hook disables /proc/acpi/ibm/bluetooth but this isn't synchronous, i. e. it doesn't wait until the module usage count actually drops to 0. Due to that, it's impossible to add btusb to SUSPEND_MODULES (on some models/older kernels you need to do that to fix suspend problems), as at that point the module is still in use. To demonstrate that, I added some logging to the hook:

==== before: =====
--- /proc/acpi/ibm/bluetooth ----
status:		enabled
commands:	enable, disable
--- rfkill list ---
0: tpacpi_bluetooth_sw: Bluetooth
	Soft blocked: no
	Hard blocked: no
1: tpacpi_wwan_sw: Wireless WAN
	Soft blocked: no
	Hard blocked: no
2: phy0: Wireless LAN
	Soft blocked: no
	Hard blocked: no
10: hci0: Bluetooth
	Soft blocked: no
	Hard blocked: no
--- lsmod ---
btusb                  18600  2 

=== after writing /proc/acpi/ibm/bluetooth ====
--- /proc/acpi/ibm/bluetooth ----
status:		disabled
commands:	enable, disable
--- rfkill list ---
0: tpacpi_bluetooth_sw: Bluetooth
	Soft blocked: yes
	Hard blocked: no
1: tpacpi_wwan_sw: Wireless WAN
	Soft blocked: no
	Hard blocked: no
2: phy0: Wireless LAN
	Soft blocked: no
	Hard blocked: no
10: hci0: Bluetooth
	Soft blocked: no
	Hard blocked: no
--- lsmod ---
btusb                  18600  2 

As we can see, /proc/acpi/ibm/bluetooth got updated, but both rfkill as well as the module usage count are still active.

=== after sleep 0.5 ====
--- /proc/acpi/ibm/bluetooth ----
status:		disabled
commands:	enable, disable
--- rfkill ---
0: tpacpi_bluetooth_sw: Bluetooth
	Soft blocked: yes
	Hard blocked: no
1: tpacpi_wwan_sw: Wireless WAN
	Soft blocked: no
	Hard blocked: no
2: phy0: Wireless LAN
	Soft blocked: no
	Hard blocked: no
--- lsmod ---
btusb                  18600  0 

Now it disappeared from rfkill and the module usage count dropped to 0.

I'll write a better hook which waits for the module to get unused.

Comment 1 Martin Pitt 2011-01-31 06:33:16 UTC

Created attachment 42750 [details] [review]
patch against git head

What do you think about this?

Comment 2 Adam Jackson 2018-06-29 19:57:20 UTC

pm-utils hasn't been touched in eight years, none of this is likely to get addressed. Closing bugs and disabling the bz product.

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