* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-22 13:01 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-01-22 13:01 UTC (permalink / raw)
To: balbi; +Cc: linux-usb, linux-kernel, Roger Quadros
Adding/removing host/gadget controller before .pm_complete()
causes a lock-up. Let's prevent any dual-role state change
between .pm_prepare() and .pm_complete() to fix this.
Signed-off-by: Roger Quadros <rogerq@ti.com>
---
drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
drivers/usb/dwc3/core.h | 5 +++++
drivers/usb/dwc3/drd.c | 10 ++++++----
3 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 42379cc..85388dd 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
#endif /* CONFIG_PM */
#ifdef CONFIG_PM_SLEEP
+static int dwc3_prepare(struct device *dev)
+{
+ struct dwc3 *dwc = dev_get_drvdata(dev);
+ unsigned long flags;
+
+ if (dwc->dr_mode == USB_DR_MODE_OTG) {
+ spin_lock_irqsave(&dwc->lock, flags);
+ dwc->dr_keep_role = true;
+ spin_unlock_irqrestore(&dwc->lock, flags);
+ }
+
+ return 0;
+}
+
+static void dwc3_complete(struct device *dev)
+{
+ struct dwc3 *dwc = dev_get_drvdata(dev);
+ unsigned long flags;
+
+ if (dwc->dr_mode == USB_DR_MODE_OTG) {
+ spin_lock_irqsave(&dwc->lock, flags);
+ dwc->dr_keep_role = false;
+ spin_unlock_irqrestore(&dwc->lock, flags);
+ dwc3_drd_update(dwc);
+ }
+}
+
static int dwc3_suspend(struct device *dev)
{
struct dwc3 *dwc = dev_get_drvdata(dev);
@@ -1451,6 +1478,10 @@ static const struct dev_pm_ops dwc3_dev_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
SET_RUNTIME_PM_OPS(dwc3_runtime_suspend, dwc3_runtime_resume,
dwc3_runtime_idle)
+#ifdef CONFIG_PM_SLEEP
+ .prepare = dwc3_prepare,
+ .complete = dwc3_complete,
+#endif
};
#ifdef CONFIG_OF
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 4a4a4c9..f5eb474 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -786,6 +786,7 @@ struct dwc3_scratchpad_array {
* @dr_mode: requested mode of operation
* @current_dr_role: current role of operation when in dual-role mode
* @desired_dr_role: desired role of operation when in dual-role mode
+ * @dr_keep_role: keep the current dual-role irrespective of ID changes
* @edev: extcon handle
* @edev_nb: extcon notifier
* @hsphy_mode: UTMI phy mode, one of following:
@@ -901,6 +902,7 @@ struct dwc3 {
enum usb_dr_mode dr_mode;
u32 current_dr_role;
u32 desired_dr_role;
+ bool dr_keep_role;
struct extcon_dev *edev;
struct notifier_block edev_nb;
enum usb_phy_interface hsphy_mode;
@@ -1227,11 +1229,14 @@ static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
#if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
int dwc3_drd_init(struct dwc3 *dwc);
void dwc3_drd_exit(struct dwc3 *dwc);
+void dwc3_drd_update(struct dwc3 *dwc);
#else
static inline int dwc3_drd_init(struct dwc3 *dwc)
{ return 0; }
static inline void dwc3_drd_exit(struct dwc3 *dwc)
{ }
+static inline void dwc3_drd_update(struct dwc3 *dwc);
+{ }
#endif
/* power management interface */
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index cc8ab9a..177a8be 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -13,7 +13,7 @@
#include "core.h"
#include "gadget.h"
-static void dwc3_drd_update(struct dwc3 *dwc)
+void dwc3_drd_update(struct dwc3 *dwc)
{
int id;
@@ -31,9 +31,11 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
{
struct dwc3 *dwc = container_of(nb, struct dwc3, edev_nb);
- dwc3_set_mode(dwc, event ?
- DWC3_GCTL_PRTCAP_HOST :
- DWC3_GCTL_PRTCAP_DEVICE);
+ if (!dwc->dr_keep_role) {
+ dwc3_set_mode(dwc, event ?
+ DWC3_GCTL_PRTCAP_HOST :
+ DWC3_GCTL_PRTCAP_DEVICE);
+ }
return NOTIFY_DONE;
}
^ permalink raw reply related [flat|nested] 19+ messages in thread* Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-23 3:45 ` Manu Gautam
0 siblings, 0 replies; 19+ messages in thread
From: Manu Gautam @ 2018-01-23 3:45 UTC (permalink / raw)
To: Roger Quadros, balbi; +Cc: linux-usb, linux-kernel
Hi,
On 1/22/2018 6:31 PM, Roger Quadros wrote:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.
What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
IMO using a freezable_wq for drd_work should address that?
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
> drivers/usb/dwc3/core.h | 5 +++++
> drivers/usb/dwc3/drd.c | 10 ++++++----
> 3 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 42379cc..85388dd 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
> #endif /* CONFIG_PM */
>
> #ifdef CONFIG_PM_SLEEP
> +static int dwc3_prepare(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = true;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + }
> +
> + return 0;
> +}
> +
> +static void dwc3_complete(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = false;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + dwc3_drd_update(dwc);
> + }
> +}
> +
> static int dwc3_suspend(struct device *dev)
> {
> struct dwc3 *dwc = dev_get_drvdata(dev);
> @@ -1451,6 +1478,10 @@ static const struct dev_pm_ops dwc3_dev_pm_ops = {
> SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
> SET_RUNTIME_PM_OPS(dwc3_runtime_suspend, dwc3_runtime_resume,
> dwc3_runtime_idle)
> +#ifdef CONFIG_PM_SLEEP
> + .prepare = dwc3_prepare,
> + .complete = dwc3_complete,
> +#endif
> };
>
> #ifdef CONFIG_OF
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 4a4a4c9..f5eb474 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -786,6 +786,7 @@ struct dwc3_scratchpad_array {
> * @dr_mode: requested mode of operation
> * @current_dr_role: current role of operation when in dual-role mode
> * @desired_dr_role: desired role of operation when in dual-role mode
> + * @dr_keep_role: keep the current dual-role irrespective of ID changes
> * @edev: extcon handle
> * @edev_nb: extcon notifier
> * @hsphy_mode: UTMI phy mode, one of following:
> @@ -901,6 +902,7 @@ struct dwc3 {
> enum usb_dr_mode dr_mode;
> u32 current_dr_role;
> u32 desired_dr_role;
> + bool dr_keep_role;
> struct extcon_dev *edev;
> struct notifier_block edev_nb;
> enum usb_phy_interface hsphy_mode;
> @@ -1227,11 +1229,14 @@ static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
> #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
> int dwc3_drd_init(struct dwc3 *dwc);
> void dwc3_drd_exit(struct dwc3 *dwc);
> +void dwc3_drd_update(struct dwc3 *dwc);
> #else
> static inline int dwc3_drd_init(struct dwc3 *dwc)
> { return 0; }
> static inline void dwc3_drd_exit(struct dwc3 *dwc)
> { }
> +static inline void dwc3_drd_update(struct dwc3 *dwc);
> +{ }
> #endif
>
> /* power management interface */
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index cc8ab9a..177a8be 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -13,7 +13,7 @@
> #include "core.h"
> #include "gadget.h"
>
> -static void dwc3_drd_update(struct dwc3 *dwc)
> +void dwc3_drd_update(struct dwc3 *dwc)
> {
> int id;
>
> @@ -31,9 +31,11 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
> {
> struct dwc3 *dwc = container_of(nb, struct dwc3, edev_nb);
>
> - dwc3_set_mode(dwc, event ?
> - DWC3_GCTL_PRTCAP_HOST :
> - DWC3_GCTL_PRTCAP_DEVICE);
> + if (!dwc->dr_keep_role) {
> + dwc3_set_mode(dwc, event ?
> + DWC3_GCTL_PRTCAP_HOST :
> + DWC3_GCTL_PRTCAP_DEVICE);
> + }
>
> return NOTIFY_DONE;
> }
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
^ permalink raw reply [flat|nested] 19+ messages in thread* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-23 3:45 ` Manu Gautam
0 siblings, 0 replies; 19+ messages in thread
From: Manu Gautam @ 2018-01-23 3:45 UTC (permalink / raw)
To: Roger Quadros, balbi; +Cc: linux-usb, linux-kernel
Hi,
On 1/22/2018 6:31 PM, Roger Quadros wrote:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.
What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
IMO using a freezable_wq for drd_work should address that?
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
> drivers/usb/dwc3/core.h | 5 +++++
> drivers/usb/dwc3/drd.c | 10 ++++++----
> 3 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 42379cc..85388dd 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
> #endif /* CONFIG_PM */
>
> #ifdef CONFIG_PM_SLEEP
> +static int dwc3_prepare(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = true;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + }
> +
> + return 0;
> +}
> +
> +static void dwc3_complete(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = false;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + dwc3_drd_update(dwc);
> + }
> +}
> +
> static int dwc3_suspend(struct device *dev)
> {
> struct dwc3 *dwc = dev_get_drvdata(dev);
> @@ -1451,6 +1478,10 @@ static const struct dev_pm_ops dwc3_dev_pm_ops = {
> SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
> SET_RUNTIME_PM_OPS(dwc3_runtime_suspend, dwc3_runtime_resume,
> dwc3_runtime_idle)
> +#ifdef CONFIG_PM_SLEEP
> + .prepare = dwc3_prepare,
> + .complete = dwc3_complete,
> +#endif
> };
>
> #ifdef CONFIG_OF
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 4a4a4c9..f5eb474 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -786,6 +786,7 @@ struct dwc3_scratchpad_array {
> * @dr_mode: requested mode of operation
> * @current_dr_role: current role of operation when in dual-role mode
> * @desired_dr_role: desired role of operation when in dual-role mode
> + * @dr_keep_role: keep the current dual-role irrespective of ID changes
> * @edev: extcon handle
> * @edev_nb: extcon notifier
> * @hsphy_mode: UTMI phy mode, one of following:
> @@ -901,6 +902,7 @@ struct dwc3 {
> enum usb_dr_mode dr_mode;
> u32 current_dr_role;
> u32 desired_dr_role;
> + bool dr_keep_role;
> struct extcon_dev *edev;
> struct notifier_block edev_nb;
> enum usb_phy_interface hsphy_mode;
> @@ -1227,11 +1229,14 @@ static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
> #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
> int dwc3_drd_init(struct dwc3 *dwc);
> void dwc3_drd_exit(struct dwc3 *dwc);
> +void dwc3_drd_update(struct dwc3 *dwc);
> #else
> static inline int dwc3_drd_init(struct dwc3 *dwc)
> { return 0; }
> static inline void dwc3_drd_exit(struct dwc3 *dwc)
> { }
> +static inline void dwc3_drd_update(struct dwc3 *dwc);
> +{ }
> #endif
>
> /* power management interface */
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index cc8ab9a..177a8be 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -13,7 +13,7 @@
> #include "core.h"
> #include "gadget.h"
>
> -static void dwc3_drd_update(struct dwc3 *dwc)
> +void dwc3_drd_update(struct dwc3 *dwc)
> {
> int id;
>
> @@ -31,9 +31,11 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
> {
> struct dwc3 *dwc = container_of(nb, struct dwc3, edev_nb);
>
> - dwc3_set_mode(dwc, event ?
> - DWC3_GCTL_PRTCAP_HOST :
> - DWC3_GCTL_PRTCAP_DEVICE);
> + if (!dwc->dr_keep_role) {
> + dwc3_set_mode(dwc, event ?
> + DWC3_GCTL_PRTCAP_HOST :
> + DWC3_GCTL_PRTCAP_DEVICE);
> + }
>
> return NOTIFY_DONE;
> }
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-23 12:41 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-01-23 12:41 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
Hi Manu,
On 23/01/18 05:45, Manu Gautam wrote:
> Hi,
>
>
> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>> Adding/removing host/gadget controller before .pm_complete()
>> causes a lock-up. Let's prevent any dual-role state change
>> between .pm_prepare() and .pm_complete() to fix this.
>
> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
> IMO using a freezable_wq for drd_work should address that?
>
I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
>
>>
<snip>
--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
^ permalink raw reply [flat|nested] 19+ messages in thread
* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-23 12:41 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-01-23 12:41 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
Hi Manu,
On 23/01/18 05:45, Manu Gautam wrote:
> Hi,
>
>
> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>> Adding/removing host/gadget controller before .pm_complete()
>> causes a lock-up. Let's prevent any dual-role state change
>> between .pm_prepare() and .pm_complete() to fix this.
>
> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
> IMO using a freezable_wq for drd_work should address that?
>
I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
>
>>
<snip>
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-24 12:19 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-01-24 12:19 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
On 23/01/18 14:41, Roger Quadros wrote:
> Hi Manu,
>
> On 23/01/18 05:45, Manu Gautam wrote:
>> Hi,
>>
>>
>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>>> Adding/removing host/gadget controller before .pm_complete()
>>> causes a lock-up. Let's prevent any dual-role state change
>>> between .pm_prepare() and .pm_complete() to fix this.
>>
>> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
>> IMO using a freezable_wq for drd_work should address that?
>>
>
> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
using freezable_wq doesn't get rid of the deadlock.
If I use freezable_wq plus add some delay before I do a dwc3_host_init()
in the work function then it starts to work.
As dependence on delay looks fragile so I'll stick to the current implementation
based on .pm_prepare/complete().
--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
^ permalink raw reply [flat|nested] 19+ messages in thread
* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-24 12:19 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-01-24 12:19 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
On 23/01/18 14:41, Roger Quadros wrote:
> Hi Manu,
>
> On 23/01/18 05:45, Manu Gautam wrote:
>> Hi,
>>
>>
>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>>> Adding/removing host/gadget controller before .pm_complete()
>>> causes a lock-up. Let's prevent any dual-role state change
>>> between .pm_prepare() and .pm_complete() to fix this.
>>
>> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
>> IMO using a freezable_wq for drd_work should address that?
>>
>
> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
using freezable_wq doesn't get rid of the deadlock.
If I use freezable_wq plus add some delay before I do a dwc3_host_init()
in the work function then it starts to work.
As dependence on delay looks fragile so I'll stick to the current implementation
based on .pm_prepare/complete().
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-25 16:11 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-01-25 16:11 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
Hi,
On 24/01/18 14:19, Roger Quadros wrote:
> On 23/01/18 14:41, Roger Quadros wrote:
>> Hi Manu,
>>
>> On 23/01/18 05:45, Manu Gautam wrote:
>>> Hi,
>>>
>>>
>>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>>>> Adding/removing host/gadget controller before .pm_complete()
>>>> causes a lock-up. Let's prevent any dual-role state change
>>>> between .pm_prepare() and .pm_complete() to fix this.
>>>
>>> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
>>> IMO using a freezable_wq for drd_work should address that?
>>>
>>
>> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
>
> using freezable_wq doesn't get rid of the deadlock.
> If I use freezable_wq plus add some delay before I do a dwc3_host_init()
> in the work function then it starts to work.
>
> As dependence on delay looks fragile so I'll stick to the current implementation
> based on .pm_prepare/complete().
>
So I was able to reproduce the lock up with my series as well. On further investigation
this is what I see.
There are 2 different scenarios.
1) controller in host mode prior to system suspend and switches to device mode during resume.
In this case when we call dwc3_host_exit() before tasks are thawed
xhci_plat_remove() seems to lock up at the second usb_remove_hcd() call.
This issue is resolved by using system_freezable_wq for the _dwc3_set_mode() function.
2) controller in device mode prior to system suspend and switches to host mode during resume.
In this case we sleep indefinitely in _dwc3_set_mode due to
dwc3_set_mode()->dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq()
This is not resolved by moving the dwc3_set_mode() call to .pm_complete() nor via the system_freezable_wq.
One way I could fix this is like so.
Felipe, could you please suggest a better way?
Maybe we need to do this in dwc3_gadget_exit() before calling usb_del_gadget_udc() ?
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index b417d9a..0c903c1 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -109,6 +109,7 @@ static void __dwc3_set_mode(struct work_struct *work)
struct dwc3 *dwc = work_to_dwc(work);
unsigned long flags;
int ret;
+ int epnum;
if (!dwc->desired_dr_role)
return;
@@ -124,6 +125,17 @@ static void __dwc3_set_mode(struct work_struct *work)
dwc3_host_exit(dwc);
break;
case DWC3_GCTL_PRTCAP_DEVICE:
+ spin_lock_irqsave(&dwc->lock, flags);
+ for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
+ struct dwc3_ep *dep = dwc->eps[epnum];
+
+ if (!dep)
+ continue;
+
+ dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
+ }
+ spin_unlock_irqrestore(&dwc->lock, flags);
+
dwc3_gadget_exit(dwc);
dwc3_event_buffers_cleanup(dwc);
break;
--
--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
^ permalink raw reply related [flat|nested] 19+ messages in thread* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-01-25 16:11 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-01-25 16:11 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
Hi,
On 24/01/18 14:19, Roger Quadros wrote:
> On 23/01/18 14:41, Roger Quadros wrote:
>> Hi Manu,
>>
>> On 23/01/18 05:45, Manu Gautam wrote:
>>> Hi,
>>>
>>>
>>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>>>> Adding/removing host/gadget controller before .pm_complete()
>>>> causes a lock-up. Let's prevent any dual-role state change
>>>> between .pm_prepare() and .pm_complete() to fix this.
>>>
>>> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
>>> IMO using a freezable_wq for drd_work should address that?
>>>
>>
>> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
>
> using freezable_wq doesn't get rid of the deadlock.
> If I use freezable_wq plus add some delay before I do a dwc3_host_init()
> in the work function then it starts to work.
>
> As dependence on delay looks fragile so I'll stick to the current implementation
> based on .pm_prepare/complete().
>
So I was able to reproduce the lock up with my series as well. On further investigation
this is what I see.
There are 2 different scenarios.
1) controller in host mode prior to system suspend and switches to device mode during resume.
In this case when we call dwc3_host_exit() before tasks are thawed
xhci_plat_remove() seems to lock up at the second usb_remove_hcd() call.
This issue is resolved by using system_freezable_wq for the _dwc3_set_mode() function.
2) controller in device mode prior to system suspend and switches to host mode during resume.
In this case we sleep indefinitely in _dwc3_set_mode due to
dwc3_set_mode()->dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq()
This is not resolved by moving the dwc3_set_mode() call to .pm_complete() nor via the system_freezable_wq.
One way I could fix this is like so.
Felipe, could you please suggest a better way?
Maybe we need to do this in dwc3_gadget_exit() before calling usb_del_gadget_udc() ?
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index b417d9a..0c903c1 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -109,6 +109,7 @@ static void __dwc3_set_mode(struct work_struct *work)
struct dwc3 *dwc = work_to_dwc(work);
unsigned long flags;
int ret;
+ int epnum;
if (!dwc->desired_dr_role)
return;
@@ -124,6 +125,17 @@ static void __dwc3_set_mode(struct work_struct *work)
dwc3_host_exit(dwc);
break;
case DWC3_GCTL_PRTCAP_DEVICE:
+ spin_lock_irqsave(&dwc->lock, flags);
+ for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
+ struct dwc3_ep *dep = dwc->eps[epnum];
+
+ if (!dep)
+ continue;
+
+ dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
+ }
+ spin_unlock_irqrestore(&dwc->lock, flags);
+
dwc3_gadget_exit(dwc);
dwc3_event_buffers_cleanup(dwc);
break;
^ permalink raw reply related [flat|nested] 19+ messages in thread* Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-02-15 7:45 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-02-15 7:45 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
Felipe,
On 25/01/18 18:11, Roger Quadros wrote:
> Hi,
>
> On 24/01/18 14:19, Roger Quadros wrote:
>> On 23/01/18 14:41, Roger Quadros wrote:
>>> Hi Manu,
>>>
>>> On 23/01/18 05:45, Manu Gautam wrote:
>>>> Hi,
>>>>
>>>>
>>>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>>>>> Adding/removing host/gadget controller before .pm_complete()
>>>>> causes a lock-up. Let's prevent any dual-role state change
>>>>> between .pm_prepare() and .pm_complete() to fix this.
>>>>
>>>> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
>>>> IMO using a freezable_wq for drd_work should address that?
>>>>
>>>
>>> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
>>
>> using freezable_wq doesn't get rid of the deadlock.
>> If I use freezable_wq plus add some delay before I do a dwc3_host_init()
>> in the work function then it starts to work.
>>
>> As dependence on delay looks fragile so I'll stick to the current implementation
>> based on .pm_prepare/complete().
>>
>
> So I was able to reproduce the lock up with my series as well. On further investigation
> this is what I see.
>
> There are 2 different scenarios.
>
> 1) controller in host mode prior to system suspend and switches to device mode during resume.
>
> In this case when we call dwc3_host_exit() before tasks are thawed
> xhci_plat_remove() seems to lock up at the second usb_remove_hcd() call.
> This issue is resolved by using system_freezable_wq for the _dwc3_set_mode() function.
>
>
> 2) controller in device mode prior to system suspend and switches to host mode during resume.
>
> In this case we sleep indefinitely in _dwc3_set_mode due to
> dwc3_set_mode()->dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq()
>
> This is not resolved by moving the dwc3_set_mode() call to .pm_complete() nor via the system_freezable_wq.
>
> One way I could fix this is like so.
>
> Felipe, could you please suggest a better way?
> Maybe we need to do this in dwc3_gadget_exit() before calling usb_del_gadget_udc() ?
Once you let me know your opinion I can revise this series. Thanks.
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index b417d9a..0c903c1 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -109,6 +109,7 @@ static void __dwc3_set_mode(struct work_struct *work)
> struct dwc3 *dwc = work_to_dwc(work);
> unsigned long flags;
> int ret;
> + int epnum;
>
> if (!dwc->desired_dr_role)
> return;
> @@ -124,6 +125,17 @@ static void __dwc3_set_mode(struct work_struct *work)
> dwc3_host_exit(dwc);
> break;
> case DWC3_GCTL_PRTCAP_DEVICE:
> + spin_lock_irqsave(&dwc->lock, flags);
> + for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
> + struct dwc3_ep *dep = dwc->eps[epnum];
> +
> + if (!dep)
> + continue;
> +
> + dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
> + }
> + spin_unlock_irqrestore(&dwc->lock, flags);
> +
> dwc3_gadget_exit(dwc);
> dwc3_event_buffers_cleanup(dwc);
> break;
>
--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
^ permalink raw reply [flat|nested] 19+ messages in thread* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-02-15 7:45 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-02-15 7:45 UTC (permalink / raw)
To: Manu Gautam, balbi; +Cc: linux-usb, linux-kernel
Felipe,
On 25/01/18 18:11, Roger Quadros wrote:
> Hi,
>
> On 24/01/18 14:19, Roger Quadros wrote:
>> On 23/01/18 14:41, Roger Quadros wrote:
>>> Hi Manu,
>>>
>>> On 23/01/18 05:45, Manu Gautam wrote:
>>>> Hi,
>>>>
>>>>
>>>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>>>>> Adding/removing host/gadget controller before .pm_complete()
>>>>> causes a lock-up. Let's prevent any dual-role state change
>>>>> between .pm_prepare() and .pm_complete() to fix this.
>>>>
>>>> What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
>>>> IMO using a freezable_wq for drd_work should address that?
>>>>
>>>
>>> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.
>>
>> using freezable_wq doesn't get rid of the deadlock.
>> If I use freezable_wq plus add some delay before I do a dwc3_host_init()
>> in the work function then it starts to work.
>>
>> As dependence on delay looks fragile so I'll stick to the current implementation
>> based on .pm_prepare/complete().
>>
>
> So I was able to reproduce the lock up with my series as well. On further investigation
> this is what I see.
>
> There are 2 different scenarios.
>
> 1) controller in host mode prior to system suspend and switches to device mode during resume.
>
> In this case when we call dwc3_host_exit() before tasks are thawed
> xhci_plat_remove() seems to lock up at the second usb_remove_hcd() call.
> This issue is resolved by using system_freezable_wq for the _dwc3_set_mode() function.
>
>
> 2) controller in device mode prior to system suspend and switches to host mode during resume.
>
> In this case we sleep indefinitely in _dwc3_set_mode due to
> dwc3_set_mode()->dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq()
>
> This is not resolved by moving the dwc3_set_mode() call to .pm_complete() nor via the system_freezable_wq.
>
> One way I could fix this is like so.
>
> Felipe, could you please suggest a better way?
> Maybe we need to do this in dwc3_gadget_exit() before calling usb_del_gadget_udc() ?
Once you let me know your opinion I can revise this series. Thanks.
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index b417d9a..0c903c1 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -109,6 +109,7 @@ static void __dwc3_set_mode(struct work_struct *work)
> struct dwc3 *dwc = work_to_dwc(work);
> unsigned long flags;
> int ret;
> + int epnum;
>
> if (!dwc->desired_dr_role)
> return;
> @@ -124,6 +125,17 @@ static void __dwc3_set_mode(struct work_struct *work)
> dwc3_host_exit(dwc);
> break;
> case DWC3_GCTL_PRTCAP_DEVICE:
> + spin_lock_irqsave(&dwc->lock, flags);
> + for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
> + struct dwc3_ep *dep = dwc->eps[epnum];
> +
> + if (!dep)
> + continue;
> +
> + dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
> + }
> + spin_unlock_irqrestore(&dwc->lock, flags);
> +
> dwc3_gadget_exit(dwc);
> dwc3_event_buffers_cleanup(dwc);
> break;
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-02-12 8:54 ` Felipe Balbi
0 siblings, 0 replies; 19+ messages in thread
From: Felipe Balbi @ 2018-02-12 8:54 UTC (permalink / raw)
To: Roger Quadros; +Cc: linux-usb, linux-kernel, Roger Quadros
[-- Attachment #1: Type: text/plain, Size: 1594 bytes --]
Hi,
Roger Quadros <rogerq@ti.com> writes:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
> drivers/usb/dwc3/core.h | 5 +++++
> drivers/usb/dwc3/drd.c | 10 ++++++----
> 3 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 42379cc..85388dd 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
> #endif /* CONFIG_PM */
>
> #ifdef CONFIG_PM_SLEEP
> +static int dwc3_prepare(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = true;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + }
> +
> + return 0;
> +}
> +
> +static void dwc3_complete(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = false;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + dwc3_drd_update(dwc);
> + }
> +}
wouldn't it be far easier to just disable OTG IRQ in prepare? and,
perhaps, also flush_work_sync() ?
--
balbi
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]
^ permalink raw reply [flat|nested] 19+ messages in thread* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-02-12 8:54 ` Felipe Balbi
0 siblings, 0 replies; 19+ messages in thread
From: Felipe Balbi @ 2018-02-12 8:54 UTC (permalink / raw)
To: Roger Quadros; +Cc: linux-usb, linux-kernel
Hi,
Roger Quadros <rogerq@ti.com> writes:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
> drivers/usb/dwc3/core.h | 5 +++++
> drivers/usb/dwc3/drd.c | 10 ++++++----
> 3 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 42379cc..85388dd 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
> #endif /* CONFIG_PM */
>
> #ifdef CONFIG_PM_SLEEP
> +static int dwc3_prepare(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = true;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + }
> +
> + return 0;
> +}
> +
> +static void dwc3_complete(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(&dwc->lock, flags);
> + dwc->dr_keep_role = false;
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + dwc3_drd_update(dwc);
> + }
> +}
wouldn't it be far easier to just disable OTG IRQ in prepare? and,
perhaps, also flush_work_sync() ?
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-02-12 10:48 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-02-12 10:48 UTC (permalink / raw)
To: Felipe Balbi; +Cc: linux-usb, linux-kernel
Felipe,
On 12/02/18 10:54, Felipe Balbi wrote:
>
> Hi,
>
> Roger Quadros <rogerq@ti.com> writes:
>> Adding/removing host/gadget controller before .pm_complete()
>> causes a lock-up. Let's prevent any dual-role state change
>> between .pm_prepare() and .pm_complete() to fix this.
>>
>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>> ---
>> drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
>> drivers/usb/dwc3/core.h | 5 +++++
>> drivers/usb/dwc3/drd.c | 10 ++++++----
>> 3 files changed, 42 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index 42379cc..85388dd 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
>> #endif /* CONFIG_PM */
>>
>> #ifdef CONFIG_PM_SLEEP
>> +static int dwc3_prepare(struct device *dev)
>> +{
>> + struct dwc3 *dwc = dev_get_drvdata(dev);
>> + unsigned long flags;
>> +
>> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
>> + spin_lock_irqsave(&dwc->lock, flags);
>> + dwc->dr_keep_role = true;
>> + spin_unlock_irqrestore(&dwc->lock, flags);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void dwc3_complete(struct device *dev)
>> +{
>> + struct dwc3 *dwc = dev_get_drvdata(dev);
>> + unsigned long flags;
>> +
>> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
>> + spin_lock_irqsave(&dwc->lock, flags);
>> + dwc->dr_keep_role = false;
>> + spin_unlock_irqrestore(&dwc->lock, flags);
>> + dwc3_drd_update(dwc);
>> + }
>> +}
>
> wouldn't it be far easier to just disable OTG IRQ in prepare? and,
> perhaps, also flush_work_sync() ?
>
There was some more discussion on this here [1]. Apparently using system_freezable_wq
and a patch mentioned at end of [1] is sufficient as well
[1] https://lkml.org/lkml/2018/1/25/384
Could you please share your view there?
--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
^ permalink raw reply [flat|nested] 19+ messages in thread* [2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume
@ 2018-02-12 10:48 ` Roger Quadros
0 siblings, 0 replies; 19+ messages in thread
From: Roger Quadros @ 2018-02-12 10:48 UTC (permalink / raw)
To: Felipe Balbi; +Cc: linux-usb, linux-kernel
Felipe,
On 12/02/18 10:54, Felipe Balbi wrote:
>
> Hi,
>
> Roger Quadros <rogerq@ti.com> writes:
>> Adding/removing host/gadget controller before .pm_complete()
>> causes a lock-up. Let's prevent any dual-role state change
>> between .pm_prepare() and .pm_complete() to fix this.
>>
>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>> ---
>> drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
>> drivers/usb/dwc3/core.h | 5 +++++
>> drivers/usb/dwc3/drd.c | 10 ++++++----
>> 3 files changed, 42 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index 42379cc..85388dd 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
>> #endif /* CONFIG_PM */
>>
>> #ifdef CONFIG_PM_SLEEP
>> +static int dwc3_prepare(struct device *dev)
>> +{
>> + struct dwc3 *dwc = dev_get_drvdata(dev);
>> + unsigned long flags;
>> +
>> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
>> + spin_lock_irqsave(&dwc->lock, flags);
>> + dwc->dr_keep_role = true;
>> + spin_unlock_irqrestore(&dwc->lock, flags);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void dwc3_complete(struct device *dev)
>> +{
>> + struct dwc3 *dwc = dev_get_drvdata(dev);
>> + unsigned long flags;
>> +
>> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
>> + spin_lock_irqsave(&dwc->lock, flags);
>> + dwc->dr_keep_role = false;
>> + spin_unlock_irqrestore(&dwc->lock, flags);
>> + dwc3_drd_update(dwc);
>> + }
>> +}
>
> wouldn't it be far easier to just disable OTG IRQ in prepare? and,
> perhaps, also flush_work_sync() ?
>
There was some more discussion on this here [1]. Apparently using system_freezable_wq
and a patch mentioned at end of [1] is sufficient as well
[1] https://lkml.org/lkml/2018/1/25/384
Could you please share your view there?
^ permalink raw reply [flat|nested] 19+ messages in thread