On Thu, 18 Oct 2018, Mayuresh Kulkarni wrote: > > The only way to make the ioctl work properly is to have it do a > > runtime-PM put at the start and then a runtime-PM get before it > > returns. This is true regardless of the reason for returning: normal > > termination, timeout, signal, whatever. Nothing else would be safe. > > > > Will below steps work safely (sometimes pseudo-code/snippets help to align)? - > > "new" ioctl - > > timeout is parameter to ioctl. > > /* attempt suspend of device */ > usb_autosuspend_device(dev); > > usb_unlock_device(dev); > r = wait_event_interruptible_timeout(ps->resume_wait, > (ps->resume_done == true), timeout * HZ); Not exactly. The condition to test here is whether the device has been suspended, so it's more like this: r = wait_event_interruptible_timeout(ps->suspend_wait, (ps->suspend_done == true), timeout * HZ); where ps->suspend_done is set by the runtime_suspend callback. After this we will do: if (r > 0) /* Device suspended before the timeout expired */ r = wait_event_interruptible(ps->resume_wait, (ps->resume_done == true)); > usb_lock_device(dev); > > /* > * There are 3 possibilities here: > * 1. Device did suspend and resume (success) > * 2. Signal was received (failed suspend) > * 3. Time-out happened (failed suspend) 4. Device did suspend but a signal was received before the device resumed. > * In any of above cases, we need to resume device. > */ > usb_autoresume_device(dev); > > ps->resume_done = false; > > "ps->resume_done = true;" will be done by the runtime resume call-back. Exactly. You got it. Will that let you accomplish what you want? Alan Stern
