Re: [PATCH] HID: usbhid: do not sleep when opening device
On Mon, Jun 1, 2020 at 7:13 PM Jiri Kosina wrote:
>
> On Fri, 29 May 2020, Dmitry Torokhov wrote:
>
> > > > > > > usbhid tries to give the device 50 milliseconds to drain its
> > > > > > > queues
> > > > > > > when opening the device, but does it naively by simply sleeping
> > > > > > > in open
> > > > > > > handler, which slows down device probing (and thus may affect
> > > > > > > overall
> > > > > > > boot time).
> > > > > > >
> > > > > > > However we do not need to sleep as we can instead mark a point of
> > > > > > > time
> > > > > > > in the future when we should start processing the events.
> > > > > > >
> > > > > > > Reported-by: Nicolas Boichat
> > > > > > > Signed-off-by: Dmitry Torokhov
> > > > > > > ---
> > > > > > > drivers/hid/usbhid/hid-core.c | 27 +++
> > > > > > > drivers/hid/usbhid/usbhid.h | 1 +
> > > > > > > 2 files changed, 16 insertions(+), 12 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/hid/usbhid/hid-core.c
> > > > > > > b/drivers/hid/usbhid/hid-core.c
> > > > > > > index c7bc9db5b192..e69992e945b2 100644
> > > > > > > --- a/drivers/hid/usbhid/hid-core.c
> > > > > > > +++ b/drivers/hid/usbhid/hid-core.c
> > > > > > > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > > > > > > set_bit(HID_NO_BANDWIDTH,
> > > > > > > >iofl);
> > > > > > > } else {
> > > > > > > clear_bit(HID_NO_BANDWIDTH,
> > > > > > > >iofl);
> > > > > > > +
> > > > > > > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > > > > > > + >iofl)) {
> > > > > > > + /*
> > > > > > > +* In case events are generated
> > > > > > > while nobody was
> > > > > > > +* listening, some are released
> > > > > > > when the device
> > > > > > > +* is re-opened. Wait 50 msec for
> > > > > > > the queue to
> > > > > > > +* empty before allowing events
> > > > > > > to go through
> > > > > > > +* hid.
> > > > > > > +*/
> > > > > > > + usbhid->input_start_time =
> > > > > > > jiffies +
> > > > > > > +
> > > > > > > msecs_to_jiffies(50);
> > > > > > > + }
> > > > > > > }
> > > > > > > }
> > > > > > > spin_unlock_irqrestore(>lock, flags);
> > > > > > > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > > > > > > if (!test_bit(HID_OPENED, >iofl))
> > > > > > > break;
> > > > > > > usbhid_mark_busy(usbhid);
> > > > > > > - if (!test_bit(HID_RESUME_RUNNING, >iofl))
> > > > > > > {
> > > > > > > + if (!test_bit(HID_RESUME_RUNNING, >iofl)
> > > > > > > &&
> > > > > > > + time_after(jiffies,
> > > > > > > usbhid->input_start_time)) {
> > > > > >
> > > > > > Are we worried about jiffies overflowing (32-bit@1000Hz is "only"
> > > > > > 49.7 days...)
> > > > > >
> > > > >
> > > > > time_after() is overflow-safe. That is why it is used and jiffies is
> > > > > not compared directly.
> > > >
> > > > Well, it is overflow safe, but still can not measure more than 50 days,
> > > > so if you have a device open for 50+ days there will be a 50msec gap
> > > > where it may lose events.
> > > >
> > >
> > > Or you could explicitly use 64-bit jiffies.
> >
> > Indeed.
> >
> > Jiri, Benjamin, do you have preference between jiffies64 and ktime_t? I
> > guess jiffies64 is a tiny bit less expensive.
>
> If I would be writing the code, I'd use ktime_t, because I personally like
> that abstraction more :) But either variant works for me.
I don't have a strong opinion on either variant. Feel free to use
whatever you like the most.
Cheers,
Benjamin
>
> Thanks!
>
> --
> Jiri Kosina
> SUSE Labs
>
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, 29 May 2020, Dmitry Torokhov wrote:
> > > > > > usbhid tries to give the device 50 milliseconds to drain its queues
> > > > > > when opening the device, but does it naively by simply sleeping in
> > > > > > open
> > > > > > handler, which slows down device probing (and thus may affect
> > > > > > overall
> > > > > > boot time).
> > > > > >
> > > > > > However we do not need to sleep as we can instead mark a point of
> > > > > > time
> > > > > > in the future when we should start processing the events.
> > > > > >
> > > > > > Reported-by: Nicolas Boichat
> > > > > > Signed-off-by: Dmitry Torokhov
> > > > > > ---
> > > > > > drivers/hid/usbhid/hid-core.c | 27 +++
> > > > > > drivers/hid/usbhid/usbhid.h | 1 +
> > > > > > 2 files changed, 16 insertions(+), 12 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/hid/usbhid/hid-core.c
> > > > > > b/drivers/hid/usbhid/hid-core.c
> > > > > > index c7bc9db5b192..e69992e945b2 100644
> > > > > > --- a/drivers/hid/usbhid/hid-core.c
> > > > > > +++ b/drivers/hid/usbhid/hid-core.c
> > > > > > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > > > > > set_bit(HID_NO_BANDWIDTH,
> > > > > > >iofl);
> > > > > > } else {
> > > > > > clear_bit(HID_NO_BANDWIDTH, >iofl);
> > > > > > +
> > > > > > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > > > > > + >iofl)) {
> > > > > > + /*
> > > > > > +* In case events are generated
> > > > > > while nobody was
> > > > > > +* listening, some are released
> > > > > > when the device
> > > > > > +* is re-opened. Wait 50 msec for
> > > > > > the queue to
> > > > > > +* empty before allowing events to
> > > > > > go through
> > > > > > +* hid.
> > > > > > +*/
> > > > > > + usbhid->input_start_time = jiffies +
> > > > > > +
> > > > > > msecs_to_jiffies(50);
> > > > > > + }
> > > > > > }
> > > > > > }
> > > > > > spin_unlock_irqrestore(>lock, flags);
> > > > > > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > > > > > if (!test_bit(HID_OPENED, >iofl))
> > > > > > break;
> > > > > > usbhid_mark_busy(usbhid);
> > > > > > - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> > > > > > + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> > > > > > + time_after(jiffies, usbhid->input_start_time)) {
> > > > >
> > > > > Are we worried about jiffies overflowing (32-bit@1000Hz is "only"
> > > > > 49.7 days...)
> > > > >
> > > >
> > > > time_after() is overflow-safe. That is why it is used and jiffies is
> > > > not compared directly.
> > >
> > > Well, it is overflow safe, but still can not measure more than 50 days,
> > > so if you have a device open for 50+ days there will be a 50msec gap
> > > where it may lose events.
> > >
> >
> > Or you could explicitly use 64-bit jiffies.
>
> Indeed.
>
> Jiri, Benjamin, do you have preference between jiffies64 and ktime_t? I
> guess jiffies64 is a tiny bit less expensive.
If I would be writing the code, I'd use ktime_t, because I personally like
that abstraction more :) But either variant works for me.
Thanks!
--
Jiri Kosina
SUSE Labs
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, May 29, 2020 at 06:22:49PM -0700, Guenter Roeck wrote:
> On Fri, May 29, 2020 at 6:09 PM Dmitry Torokhov
> wrote:
> >
> > On Fri, May 29, 2020 at 05:48:26PM -0700, Guenter Roeck wrote:
> > > On Fri, May 29, 2020 at 4:50 PM Nicolas Boichat
> > > wrote:
> > > >
> > > > On Sat, May 30, 2020 at 3:59 AM Dmitry Torokhov
> > > > wrote:
> > > > >
> > > > > usbhid tries to give the device 50 milliseconds to drain its queues
> > > > > when opening the device, but does it naively by simply sleeping in
> > > > > open
> > > > > handler, which slows down device probing (and thus may affect overall
> > > > > boot time).
> > > > >
> > > > > However we do not need to sleep as we can instead mark a point of time
> > > > > in the future when we should start processing the events.
> > > > >
> > > > > Reported-by: Nicolas Boichat
> > > > > Signed-off-by: Dmitry Torokhov
> > > > > ---
> > > > > drivers/hid/usbhid/hid-core.c | 27 +++
> > > > > drivers/hid/usbhid/usbhid.h | 1 +
> > > > > 2 files changed, 16 insertions(+), 12 deletions(-)
> > > > >
> > > > > diff --git a/drivers/hid/usbhid/hid-core.c
> > > > > b/drivers/hid/usbhid/hid-core.c
> > > > > index c7bc9db5b192..e69992e945b2 100644
> > > > > --- a/drivers/hid/usbhid/hid-core.c
> > > > > +++ b/drivers/hid/usbhid/hid-core.c
> > > > > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > > > > set_bit(HID_NO_BANDWIDTH,
> > > > > >iofl);
> > > > > } else {
> > > > > clear_bit(HID_NO_BANDWIDTH, >iofl);
> > > > > +
> > > > > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > > > > + >iofl)) {
> > > > > + /*
> > > > > +* In case events are generated while
> > > > > nobody was
> > > > > +* listening, some are released when
> > > > > the device
> > > > > +* is re-opened. Wait 50 msec for the
> > > > > queue to
> > > > > +* empty before allowing events to go
> > > > > through
> > > > > +* hid.
> > > > > +*/
> > > > > + usbhid->input_start_time = jiffies +
> > > > > +
> > > > > msecs_to_jiffies(50);
> > > > > + }
> > > > > }
> > > > > }
> > > > > spin_unlock_irqrestore(>lock, flags);
> > > > > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > > > > if (!test_bit(HID_OPENED, >iofl))
> > > > > break;
> > > > > usbhid_mark_busy(usbhid);
> > > > > - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> > > > > + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> > > > > + time_after(jiffies, usbhid->input_start_time)) {
> > > >
> > > > Are we worried about jiffies overflowing (32-bit@1000Hz is "only" 49.7
> > > > days...)
> > > >
> > >
> > > time_after() is overflow-safe. That is why it is used and jiffies is
> > > not compared directly.
> >
> > Well, it is overflow safe, but still can not measure more than 50 days,
> > so if you have a device open for 50+ days there will be a 50msec gap
> > where it may lose events.
> >
>
> Or you could explicitly use 64-bit jiffies.
Indeed.
Jiri, Benjamin, do you have preference between jiffies64 and ktime_t? I
guess jiffies64 is a tiny bit less expensive.
Thanks.
--
Dmitry
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, May 29, 2020 at 6:09 PM Dmitry Torokhov
wrote:
>
> On Fri, May 29, 2020 at 05:48:26PM -0700, Guenter Roeck wrote:
> > On Fri, May 29, 2020 at 4:50 PM Nicolas Boichat
> > wrote:
> > >
> > > On Sat, May 30, 2020 at 3:59 AM Dmitry Torokhov
> > > wrote:
> > > >
> > > > usbhid tries to give the device 50 milliseconds to drain its queues
> > > > when opening the device, but does it naively by simply sleeping in open
> > > > handler, which slows down device probing (and thus may affect overall
> > > > boot time).
> > > >
> > > > However we do not need to sleep as we can instead mark a point of time
> > > > in the future when we should start processing the events.
> > > >
> > > > Reported-by: Nicolas Boichat
> > > > Signed-off-by: Dmitry Torokhov
> > > > ---
> > > > drivers/hid/usbhid/hid-core.c | 27 +++
> > > > drivers/hid/usbhid/usbhid.h | 1 +
> > > > 2 files changed, 16 insertions(+), 12 deletions(-)
> > > >
> > > > diff --git a/drivers/hid/usbhid/hid-core.c
> > > > b/drivers/hid/usbhid/hid-core.c
> > > > index c7bc9db5b192..e69992e945b2 100644
> > > > --- a/drivers/hid/usbhid/hid-core.c
> > > > +++ b/drivers/hid/usbhid/hid-core.c
> > > > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > > > set_bit(HID_NO_BANDWIDTH,
> > > > >iofl);
> > > > } else {
> > > > clear_bit(HID_NO_BANDWIDTH, >iofl);
> > > > +
> > > > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > > > + >iofl)) {
> > > > + /*
> > > > +* In case events are generated while
> > > > nobody was
> > > > +* listening, some are released when
> > > > the device
> > > > +* is re-opened. Wait 50 msec for the
> > > > queue to
> > > > +* empty before allowing events to go
> > > > through
> > > > +* hid.
> > > > +*/
> > > > + usbhid->input_start_time = jiffies +
> > > > +
> > > > msecs_to_jiffies(50);
> > > > + }
> > > > }
> > > > }
> > > > spin_unlock_irqrestore(>lock, flags);
> > > > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > > > if (!test_bit(HID_OPENED, >iofl))
> > > > break;
> > > > usbhid_mark_busy(usbhid);
> > > > - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> > > > + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> > > > + time_after(jiffies, usbhid->input_start_time)) {
> > >
> > > Are we worried about jiffies overflowing (32-bit@1000Hz is "only" 49.7
> > > days...)
> > >
> >
> > time_after() is overflow-safe. That is why it is used and jiffies is
> > not compared directly.
>
> Well, it is overflow safe, but still can not measure more than 50 days,
> so if you have a device open for 50+ days there will be a 50msec gap
> where it may lose events.
>
Or you could explicitly use 64-bit jiffies.
Guenter
> I guess we can switch to ktime(). A bit more expensive on 32 bits, but
> in reality I do not think anyone would care.
>
> Thanks.
>
> --
> Dmitry
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, May 29, 2020 at 05:48:26PM -0700, Guenter Roeck wrote:
> On Fri, May 29, 2020 at 4:50 PM Nicolas Boichat wrote:
> >
> > On Sat, May 30, 2020 at 3:59 AM Dmitry Torokhov
> > wrote:
> > >
> > > usbhid tries to give the device 50 milliseconds to drain its queues
> > > when opening the device, but does it naively by simply sleeping in open
> > > handler, which slows down device probing (and thus may affect overall
> > > boot time).
> > >
> > > However we do not need to sleep as we can instead mark a point of time
> > > in the future when we should start processing the events.
> > >
> > > Reported-by: Nicolas Boichat
> > > Signed-off-by: Dmitry Torokhov
> > > ---
> > > drivers/hid/usbhid/hid-core.c | 27 +++
> > > drivers/hid/usbhid/usbhid.h | 1 +
> > > 2 files changed, 16 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> > > index c7bc9db5b192..e69992e945b2 100644
> > > --- a/drivers/hid/usbhid/hid-core.c
> > > +++ b/drivers/hid/usbhid/hid-core.c
> > > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > > set_bit(HID_NO_BANDWIDTH, >iofl);
> > > } else {
> > > clear_bit(HID_NO_BANDWIDTH, >iofl);
> > > +
> > > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > > + >iofl)) {
> > > + /*
> > > +* In case events are generated while
> > > nobody was
> > > +* listening, some are released when the
> > > device
> > > +* is re-opened. Wait 50 msec for the
> > > queue to
> > > +* empty before allowing events to go
> > > through
> > > +* hid.
> > > +*/
> > > + usbhid->input_start_time = jiffies +
> > > +
> > > msecs_to_jiffies(50);
> > > + }
> > > }
> > > }
> > > spin_unlock_irqrestore(>lock, flags);
> > > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > > if (!test_bit(HID_OPENED, >iofl))
> > > break;
> > > usbhid_mark_busy(usbhid);
> > > - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> > > + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> > > + time_after(jiffies, usbhid->input_start_time)) {
> >
> > Are we worried about jiffies overflowing (32-bit@1000Hz is "only" 49.7
> > days...)
> >
>
> time_after() is overflow-safe. That is why it is used and jiffies is
> not compared directly.
Well, it is overflow safe, but still can not measure more than 50 days,
so if you have a device open for 50+ days there will be a 50msec gap
where it may lose events.
I guess we can switch to ktime(). A bit more expensive on 32 bits, but
in reality I do not think anyone would care.
Thanks.
--
Dmitry
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, May 29, 2020 at 4:50 PM Nicolas Boichat wrote:
>
> On Sat, May 30, 2020 at 3:59 AM Dmitry Torokhov
> wrote:
> >
> > usbhid tries to give the device 50 milliseconds to drain its queues
> > when opening the device, but does it naively by simply sleeping in open
> > handler, which slows down device probing (and thus may affect overall
> > boot time).
> >
> > However we do not need to sleep as we can instead mark a point of time
> > in the future when we should start processing the events.
> >
> > Reported-by: Nicolas Boichat
> > Signed-off-by: Dmitry Torokhov
> > ---
> > drivers/hid/usbhid/hid-core.c | 27 +++
> > drivers/hid/usbhid/usbhid.h | 1 +
> > 2 files changed, 16 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> > index c7bc9db5b192..e69992e945b2 100644
> > --- a/drivers/hid/usbhid/hid-core.c
> > +++ b/drivers/hid/usbhid/hid-core.c
> > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > set_bit(HID_NO_BANDWIDTH, >iofl);
> > } else {
> > clear_bit(HID_NO_BANDWIDTH, >iofl);
> > +
> > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > + >iofl)) {
> > + /*
> > +* In case events are generated while
> > nobody was
> > +* listening, some are released when the
> > device
> > +* is re-opened. Wait 50 msec for the queue
> > to
> > +* empty before allowing events to go
> > through
> > +* hid.
> > +*/
> > + usbhid->input_start_time = jiffies +
> > +
> > msecs_to_jiffies(50);
> > + }
> > }
> > }
> > spin_unlock_irqrestore(>lock, flags);
> > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > if (!test_bit(HID_OPENED, >iofl))
> > break;
> > usbhid_mark_busy(usbhid);
> > - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> > + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> > + time_after(jiffies, usbhid->input_start_time)) {
>
> Are we worried about jiffies overflowing (32-bit@1000Hz is "only" 49.7
> days...)
>
time_after() is overflow-safe. That is why it is used and jiffies is
not compared directly.
Guenter
> > hid_input_report(urb->context, HID_INPUT_REPORT,
> > urb->transfer_buffer,
> > urb->actual_length, 1);
> > @@ -714,17 +728,6 @@ static int usbhid_open(struct hid_device *hid)
> > }
> >
> > usb_autopm_put_interface(usbhid->intf);
> > -
> > - /*
> > -* In case events are generated while nobody was listening,
> > -* some are released when the device is re-opened.
> > -* Wait 50 msec for the queue to empty before allowing events
> > -* to go through hid.
> > -*/
> > - if (res == 0)
> > - msleep(50);
> > -
> > - clear_bit(HID_RESUME_RUNNING, >iofl);
> > return res;
> > }
> >
> > diff --git a/drivers/hid/usbhid/usbhid.h b/drivers/hid/usbhid/usbhid.h
> > index 8620408bd7af..805949671b96 100644
> > --- a/drivers/hid/usbhid/usbhid.h
> > +++ b/drivers/hid/usbhid/usbhid.h
> > @@ -82,6 +82,7 @@ struct usbhid_device {
> >
> > spinlock_t lock;/*
> > fifo spinlock */
> > unsigned long iofl; /*
> > I/O flags (CTRL_RUNNING, OUT_RUNNING) */
> > + unsigned long input_start_time; /*
> > When to start handling input, in jiffies */
> > struct timer_list io_retry; /*
> > Retry timer */
> > unsigned long stop_retry; /*
> > Time to give up, in jiffies */
> > unsigned int retry_delay; /*
> > Delay length in ms */
> > --
> > 2.27.0.rc0.183.gde8f92d652-goog
> >
> >
> > --
> > Dmitry
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Sat, May 30, 2020 at 3:59 AM Dmitry Torokhov
wrote:
>
> usbhid tries to give the device 50 milliseconds to drain its queues
> when opening the device, but does it naively by simply sleeping in open
> handler, which slows down device probing (and thus may affect overall
> boot time).
>
> However we do not need to sleep as we can instead mark a point of time
> in the future when we should start processing the events.
>
> Reported-by: Nicolas Boichat
> Signed-off-by: Dmitry Torokhov
> ---
> drivers/hid/usbhid/hid-core.c | 27 +++
> drivers/hid/usbhid/usbhid.h | 1 +
> 2 files changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> index c7bc9db5b192..e69992e945b2 100644
> --- a/drivers/hid/usbhid/hid-core.c
> +++ b/drivers/hid/usbhid/hid-core.c
> @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> set_bit(HID_NO_BANDWIDTH, >iofl);
> } else {
> clear_bit(HID_NO_BANDWIDTH, >iofl);
> +
> + if (test_and_clear_bit(HID_RESUME_RUNNING,
> + >iofl)) {
> + /*
> +* In case events are generated while nobody
> was
> +* listening, some are released when the
> device
> +* is re-opened. Wait 50 msec for the queue to
> +* empty before allowing events to go through
> +* hid.
> +*/
> + usbhid->input_start_time = jiffies +
> +
> msecs_to_jiffies(50);
> + }
> }
> }
> spin_unlock_irqrestore(>lock, flags);
> @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> if (!test_bit(HID_OPENED, >iofl))
> break;
> usbhid_mark_busy(usbhid);
> - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> + time_after(jiffies, usbhid->input_start_time)) {
Are we worried about jiffies overflowing (32-bit@1000Hz is "only" 49.7 days...)
> hid_input_report(urb->context, HID_INPUT_REPORT,
> urb->transfer_buffer,
> urb->actual_length, 1);
> @@ -714,17 +728,6 @@ static int usbhid_open(struct hid_device *hid)
> }
>
> usb_autopm_put_interface(usbhid->intf);
> -
> - /*
> -* In case events are generated while nobody was listening,
> -* some are released when the device is re-opened.
> -* Wait 50 msec for the queue to empty before allowing events
> -* to go through hid.
> -*/
> - if (res == 0)
> - msleep(50);
> -
> - clear_bit(HID_RESUME_RUNNING, >iofl);
> return res;
> }
>
> diff --git a/drivers/hid/usbhid/usbhid.h b/drivers/hid/usbhid/usbhid.h
> index 8620408bd7af..805949671b96 100644
> --- a/drivers/hid/usbhid/usbhid.h
> +++ b/drivers/hid/usbhid/usbhid.h
> @@ -82,6 +82,7 @@ struct usbhid_device {
>
> spinlock_t lock;/*
> fifo spinlock */
> unsigned long iofl; /*
> I/O flags (CTRL_RUNNING, OUT_RUNNING) */
> + unsigned long input_start_time; /*
> When to start handling input, in jiffies */
> struct timer_list io_retry; /*
> Retry timer */
> unsigned long stop_retry; /*
> Time to give up, in jiffies */
> unsigned int retry_delay; /*
> Delay length in ms */
> --
> 2.27.0.rc0.183.gde8f92d652-goog
>
>
> --
> Dmitry
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, May 29, 2020 at 01:33:24PM -0700, Dmitry Torokhov wrote:
> On Fri, May 29, 2020 at 01:14:24PM -0700, Guenter Roeck wrote:
> > On Fri, May 29, 2020 at 12:59:51PM -0700, Dmitry Torokhov wrote:
> > > usbhid tries to give the device 50 milliseconds to drain its queues
> > > when opening the device, but does it naively by simply sleeping in open
> > > handler, which slows down device probing (and thus may affect overall
> > > boot time).
> > >
> > > However we do not need to sleep as we can instead mark a point of time
> > > in the future when we should start processing the events.
> > >
> > > Reported-by: Nicolas Boichat
> > > Signed-off-by: Dmitry Torokhov
> > > ---
> > > drivers/hid/usbhid/hid-core.c | 27 +++
> > > drivers/hid/usbhid/usbhid.h | 1 +
> > > 2 files changed, 16 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> > > index c7bc9db5b192..e69992e945b2 100644
> > > --- a/drivers/hid/usbhid/hid-core.c
> > > +++ b/drivers/hid/usbhid/hid-core.c
> > > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > > set_bit(HID_NO_BANDWIDTH, >iofl);
> > > } else {
> > > clear_bit(HID_NO_BANDWIDTH, >iofl);
> > > +
> > > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > > +>iofl)) {
> > > + /*
> > > + * In case events are generated while nobody was
> > > + * listening, some are released when the device
> > > + * is re-opened. Wait 50 msec for the queue to
> > > + * empty before allowing events to go through
> > > + * hid.
> > > + */
> > > + usbhid->input_start_time = jiffies +
> > > +msecs_to_jiffies(50);
> > > + }
> > > }
> > > }
> > > spin_unlock_irqrestore(>lock, flags);
> > > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > > if (!test_bit(HID_OPENED, >iofl))
> > > break;
> > > usbhid_mark_busy(usbhid);
> > > - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> > > + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> > > + time_after(jiffies, usbhid->input_start_time)) {
> > > hid_input_report(urb->context, HID_INPUT_REPORT,
> > >urb->transfer_buffer,
> > >urb->actual_length, 1);
> > > @@ -714,17 +728,6 @@ static int usbhid_open(struct hid_device *hid)
> > > }
> > >
> > > usb_autopm_put_interface(usbhid->intf);
> > > -
> > > - /*
> > > - * In case events are generated while nobody was listening,
> > > - * some are released when the device is re-opened.
> > > - * Wait 50 msec for the queue to empty before allowing events
> > > - * to go through hid.
> > > - */
> > > - if (res == 0)
> > > - msleep(50);
> > > -
> > Can you just set usbhid->input_start_time here ?
> > if (res == 0)
> > usbhid->input_start_time = jiffies + msecs_to_jiffies(50);
> > clear_bit(HID_RESUME_RUNNING, >iofl);
> >
> > Then you might not need the added code in hid_start_in().
>
> That was my first version, but if hid_start_in() fails we start a timer
> and try to retry the IO (and the "res" in 0 in this case). And we want
> to mark the time only after we successfully submitted the interrupt URB,
> that is why the code is in hid_start_in().
>
Ah yes, that makes sense.
Reviewed-by: Guenter Roeck
Thanks,
Guenter
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, May 29, 2020 at 01:14:24PM -0700, Guenter Roeck wrote:
> On Fri, May 29, 2020 at 12:59:51PM -0700, Dmitry Torokhov wrote:
> > usbhid tries to give the device 50 milliseconds to drain its queues
> > when opening the device, but does it naively by simply sleeping in open
> > handler, which slows down device probing (and thus may affect overall
> > boot time).
> >
> > However we do not need to sleep as we can instead mark a point of time
> > in the future when we should start processing the events.
> >
> > Reported-by: Nicolas Boichat
> > Signed-off-by: Dmitry Torokhov
> > ---
> > drivers/hid/usbhid/hid-core.c | 27 +++
> > drivers/hid/usbhid/usbhid.h | 1 +
> > 2 files changed, 16 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> > index c7bc9db5b192..e69992e945b2 100644
> > --- a/drivers/hid/usbhid/hid-core.c
> > +++ b/drivers/hid/usbhid/hid-core.c
> > @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> > set_bit(HID_NO_BANDWIDTH, >iofl);
> > } else {
> > clear_bit(HID_NO_BANDWIDTH, >iofl);
> > +
> > + if (test_and_clear_bit(HID_RESUME_RUNNING,
> > + >iofl)) {
> > + /*
> > +* In case events are generated while nobody was
> > +* listening, some are released when the device
> > +* is re-opened. Wait 50 msec for the queue to
> > +* empty before allowing events to go through
> > +* hid.
> > +*/
> > + usbhid->input_start_time = jiffies +
> > + msecs_to_jiffies(50);
> > + }
> > }
> > }
> > spin_unlock_irqrestore(>lock, flags);
> > @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> > if (!test_bit(HID_OPENED, >iofl))
> > break;
> > usbhid_mark_busy(usbhid);
> > - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> > + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> > + time_after(jiffies, usbhid->input_start_time)) {
> > hid_input_report(urb->context, HID_INPUT_REPORT,
> > urb->transfer_buffer,
> > urb->actual_length, 1);
> > @@ -714,17 +728,6 @@ static int usbhid_open(struct hid_device *hid)
> > }
> >
> > usb_autopm_put_interface(usbhid->intf);
> > -
> > - /*
> > -* In case events are generated while nobody was listening,
> > -* some are released when the device is re-opened.
> > -* Wait 50 msec for the queue to empty before allowing events
> > -* to go through hid.
> > -*/
> > - if (res == 0)
> > - msleep(50);
> > -
> Can you just set usbhid->input_start_time here ?
> if (res == 0)
> usbhid->input_start_time = jiffies + msecs_to_jiffies(50);
> clear_bit(HID_RESUME_RUNNING, >iofl);
>
> Then you might not need the added code in hid_start_in().
That was my first version, but if hid_start_in() fails we start a timer
and try to retry the IO (and the "res" in 0 in this case). And we want
to mark the time only after we successfully submitted the interrupt URB,
that is why the code is in hid_start_in().
Thanks.
--
Dmitry
Re: [PATCH] HID: usbhid: do not sleep when opening device
On Fri, May 29, 2020 at 12:59:51PM -0700, Dmitry Torokhov wrote:
> usbhid tries to give the device 50 milliseconds to drain its queues
> when opening the device, but does it naively by simply sleeping in open
> handler, which slows down device probing (and thus may affect overall
> boot time).
>
> However we do not need to sleep as we can instead mark a point of time
> in the future when we should start processing the events.
>
> Reported-by: Nicolas Boichat
> Signed-off-by: Dmitry Torokhov
> ---
> drivers/hid/usbhid/hid-core.c | 27 +++
> drivers/hid/usbhid/usbhid.h | 1 +
> 2 files changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> index c7bc9db5b192..e69992e945b2 100644
> --- a/drivers/hid/usbhid/hid-core.c
> +++ b/drivers/hid/usbhid/hid-core.c
> @@ -95,6 +95,19 @@ static int hid_start_in(struct hid_device *hid)
> set_bit(HID_NO_BANDWIDTH, >iofl);
> } else {
> clear_bit(HID_NO_BANDWIDTH, >iofl);
> +
> + if (test_and_clear_bit(HID_RESUME_RUNNING,
> +>iofl)) {
> + /*
> + * In case events are generated while nobody was
> + * listening, some are released when the device
> + * is re-opened. Wait 50 msec for the queue to
> + * empty before allowing events to go through
> + * hid.
> + */
> + usbhid->input_start_time = jiffies +
> +msecs_to_jiffies(50);
> + }
> }
> }
> spin_unlock_irqrestore(>lock, flags);
> @@ -280,7 +293,8 @@ static void hid_irq_in(struct urb *urb)
> if (!test_bit(HID_OPENED, >iofl))
> break;
> usbhid_mark_busy(usbhid);
> - if (!test_bit(HID_RESUME_RUNNING, >iofl)) {
> + if (!test_bit(HID_RESUME_RUNNING, >iofl) &&
> + time_after(jiffies, usbhid->input_start_time)) {
> hid_input_report(urb->context, HID_INPUT_REPORT,
>urb->transfer_buffer,
>urb->actual_length, 1);
> @@ -714,17 +728,6 @@ static int usbhid_open(struct hid_device *hid)
> }
>
> usb_autopm_put_interface(usbhid->intf);
> -
> - /*
> - * In case events are generated while nobody was listening,
> - * some are released when the device is re-opened.
> - * Wait 50 msec for the queue to empty before allowing events
> - * to go through hid.
> - */
> - if (res == 0)
> - msleep(50);
> -
Can you just set usbhid->input_start_time here ?
if (res == 0)
usbhid->input_start_time = jiffies + msecs_to_jiffies(50);
clear_bit(HID_RESUME_RUNNING, >iofl);
Then you might not need the added code in hid_start_in().
Thanks,
Guenter
> - clear_bit(HID_RESUME_RUNNING, >iofl);
> return res;
> }
>
> diff --git a/drivers/hid/usbhid/usbhid.h b/drivers/hid/usbhid/usbhid.h
> index 8620408bd7af..805949671b96 100644
> --- a/drivers/hid/usbhid/usbhid.h
> +++ b/drivers/hid/usbhid/usbhid.h
> @@ -82,6 +82,7 @@ struct usbhid_device {
>
> spinlock_t lock;/* fifo
> spinlock */
> unsigned long iofl; /* I/O
> flags (CTRL_RUNNING, OUT_RUNNING) */
> + unsigned long input_start_time; /* When
> to start handling input, in jiffies */
> struct timer_list io_retry; /*
> Retry timer */
> unsigned long stop_retry; /* Time
> to give up, in jiffies */
> unsigned int retry_delay; /*
> Delay length in ms */
> --
> 2.27.0.rc0.183.gde8f92d652-goog
>
>
> --
> Dmitry
