| Message ID | 1400838066.29150.69.camel@pasglop (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Fri, 2014-05-23 at 19:41 +1000, Benjamin Herrenschmidt wrote: > Some backends call hvc_kick() to wakeup the HVC thread from its > slumber upon incoming characters. This however doesn't work > properly because it uses msleep_interruptible() which is mostly > immune to wake_up_process(). It will basically go back to sleep > until the timeout is expired (only signals can really wake it). > > Replace it with a simple shedule_timeout_interruptible() instead, > which may wakeup earlier every now and then but we really don't > care in this case. Nobody commented ? :-) Greg, do you want to take this in the tty tree or can I stick it in powerpc ? Cheers, Ben > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> > --- > drivers/tty/hvc/hvc_console.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c > index 94f9e3a..1094265 100644 > --- a/drivers/tty/hvc/hvc_console.c > +++ b/drivers/tty/hvc/hvc_console.c > @@ -760,10 +760,17 @@ static int khvcd(void *unused) > if (poll_mask == 0) > schedule(); > else { > + unsigned long j_timeout; > + > if (timeout < MAX_TIMEOUT) > timeout += (timeout >> 6) + 1; > > - msleep_interruptible(timeout); > + /* > + * We don't use msleep_interruptible otherwise > + * "kick" will fail to wake us up > + */ > + j_timeout = msecs_to_jiffies(timeout) + 1; > + schedule_timeout_interruptible(j_timeout); > } > } > __set_current_state(TASK_RUNNING); >
On Wed, May 28, 2014 at 10:01:30AM +1000, Benjamin Herrenschmidt wrote: > On Fri, 2014-05-23 at 19:41 +1000, Benjamin Herrenschmidt wrote: > > Some backends call hvc_kick() to wakeup the HVC thread from its > > slumber upon incoming characters. This however doesn't work > > properly because it uses msleep_interruptible() which is mostly > > immune to wake_up_process(). It will basically go back to sleep > > until the timeout is expired (only signals can really wake it). > > > > Replace it with a simple shedule_timeout_interruptible() instead, > > which may wakeup earlier every now and then but we really don't > > care in this case. > > Nobody commented ? :-) > > Greg, do you want to take this in the tty tree or can I stick it in > powerpc ? I'll take it, thanks. greg k-h
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index 94f9e3a..1094265 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -760,10 +760,17 @@ static int khvcd(void *unused) if (poll_mask == 0) schedule(); else { + unsigned long j_timeout; + if (timeout < MAX_TIMEOUT) timeout += (timeout >> 6) + 1; - msleep_interruptible(timeout); + /* + * We don't use msleep_interruptible otherwise + * "kick" will fail to wake us up + */ + j_timeout = msecs_to_jiffies(timeout) + 1; + schedule_timeout_interruptible(j_timeout); } } __set_current_state(TASK_RUNNING);
Some backends call hvc_kick() to wakeup the HVC thread from its slumber upon incoming characters. This however doesn't work properly because it uses msleep_interruptible() which is mostly immune to wake_up_process(). It will basically go back to sleep until the timeout is expired (only signals can really wake it). Replace it with a simple shedule_timeout_interruptible() instead, which may wakeup earlier every now and then but we really don't care in this case. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- drivers/tty/hvc/hvc_console.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)