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Commit 8bc7337c authored by Saravana Kannan's avatar Saravana Kannan Committed by Srinivasarao P
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UPSTREAM: driver core: Don't do deferred probe in parallel with kernel_init thread 

The current deferred probe implementation can mess up suspend/resume
ordering if deferred probe thread is kicked off in parallel with the
main initcall thread (kernel_init thread) [1].

For example:

Say device-B is a consumer of device-A.

Initcall thread					Deferred probe thread
===============					=====================
1. device-A is added.
2. device-B is added.
3. dpm_list is now [device-A, device-B].
4. driver-A defers probe of device-A.
						5. device-A is moved to
						   end of dpm_list
						6. dpm_list is now
						   [device-B, device-A]
7. driver-B is registereed and probes device-B.
8. dpm_list stays as [device-B, device-A].

The reverse order of dpm_list is used for suspend. So in this case
device-A would incorrectly get suspended before device-B.

Commit 716a7a259690 ("driver core: fw_devlink: Add support for batching
fwnode parsing") kicked off the deferred probe thread early during boot
to run in parallel with the initcall thread and caused suspend/resume
regressions.  This patch removes the parallel run of the deferred probe
thread to avoid the suspend/resume regressions.

[1] - https://lore.kernel.org/lkml/CAGETcx8W96KAw-d_siTX4qHB_-7ddk0miYRDQeHE6E0_8qx-6Q@mail.gmail.com/



Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing")
Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Tested-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200701194259.3337652-2-saravanak@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit cec72f3efc6272420c2c2c699607f03d09b93e41)
Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Bug: 157691602
Change-Id: I13f61a7cbeb705eb6ca1c67b07df5a9b69045029
Git-repo: https://android.googlesource.com/kernel/common


Git-commit: 2b2b5b944c36f9ba96a110d6db76ce68ee5b94f4
Signed-off-by: default avatarSrinivasarao P <spathi@codeaurora.org>
parent b5b876a9

drivers/base/base.h

+0 −1
Original line number Diff line number Diff line
@@ -134,7 +134,6 @@ extern char *make_class_name(const char *name, struct kobject *kobj); 
extern int devres_release_all(struct device *dev);

extern void device_block_probing(void);

extern void device_unblock_probing(void);

extern void driver_deferred_probe_force_trigger(void);



/* /sys/devices directory */

extern struct kset *devices_kset;

drivers/base/core.c

+0 −1
Original line number Diff line number Diff line
@@ -1272,7 +1272,6 @@ void fw_devlink_resume(void) 
		goto out;



	device_link_add_missing_supplier_links();

	driver_deferred_probe_force_trigger();

out:

	mutex_unlock(&defer_fw_devlink_lock);

}

drivers/base/dd.c

+0 −5
Original line number Diff line number Diff line
@@ -160,11 +160,6 @@ static void driver_deferred_probe_trigger(void) 
	if (!driver_deferred_probe_enable)

		return;



	driver_deferred_probe_force_trigger();

}



void driver_deferred_probe_force_trigger(void)

{

	/*

	 * A successful probe means that all the devices in the pending list

	 * should be triggered to be reprobed.  Move all the deferred devices