Messages in this thread Patch in this message | | | Date | Wed, 1 Jul 2020 12:42:57 -0700 | Subject | [PATCH v1 1/3] driver core: Don't do deferred probe in parallel with kernel_init thread | From | Saravana Kannan <> |
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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: Saravana Kannan <saravanak@google.com> --- drivers/base/base.h | 1 - drivers/base/core.c | 1 - drivers/base/dd.c | 5 ----- 3 files changed, 7 deletions(-)
diff --git a/drivers/base/base.h b/drivers/base/base.h index 95c22c0f9036..40fb069a8a7e 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -153,7 +153,6 @@ 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; diff --git a/drivers/base/core.c b/drivers/base/core.c index 67d39a90b45c..35cc9896eb9e 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1323,7 +1323,6 @@ 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); } diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 9a1d940342ac..48ca81cb8ebc 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -164,11 +164,6 @@ 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 -- 2.27.0.212.ge8ba1cc988-goog
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