Re: [PATCH] PM: Acquire device locks on suspend

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From: Rafael J. Wysocki
Date: Sunday, January 6, 2008 - 3:34 pm

On Sunday, 6 of January 2008, Alan Stern wrote:

Still, if we do that, we won't need to acquire dev->sem in device_pm_remove()
any more.  Apart from this, by acqiring pm_sleep_rwsem for reading in
device_del() we can prevent a suspend from starting while the device is being
removed.

Consider, for example, the scenario possible with the $subject patch:
- device_del() starts and notices pm_sleep_rwsem unlocked, so the warning is
  not printed
- it proceeds and everything before device_pm_remove() succeeds
- now, device_suspend() is called and locks dev->sem
- device_del() calls device_pm_remove() and blocks on that with the device
  partialy removed
I think we should prevent this from happening.

Rafael
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Messages in current thread:
[PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sat Jan 5, 11:36 am)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sat Jan 5, 1:08 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sat Jan 5, 1:19 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sat Jan 5, 1:39 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sat Jan 5, 2:13 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sat Jan 5, 2:41 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sat Jan 5, 2:58 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sat Jan 5, 9:04 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sun Jan 6, 6:19 am)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sun Jan 6, 10:06 am)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sun Jan 6, 12:05 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sun Jan 6, 12:57 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sun Jan 6, 3:11 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sun Jan 6, 3:19 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sun Jan 6, 3:21 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Sun Jan 6, 3:31 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sun Jan 6, 3:34 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Sun Jan 6, 3:47 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Mon Jan 7, 9:16 am)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Mon Jan 7, 9:51 am)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Mon Jan 7, 10:23 am)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Mon Jan 7, 11:01 am)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Mon Jan 7, 12:29 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Mon Jan 7, 1:37 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Mon Jan 7, 2:32 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Mon Jan 7, 5:25 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Wed Jan 9, 2:01 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Wed Jan 9, 3:14 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Wed Jan 9, 3:46 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Wed Jan 9, 4:29 pm)
Re: [PATCH] PM: Acquire device locks on suspend, Rafael J. Wysocki, (Thu Jan 10, 9:59 am)
Re: [PATCH] PM: Acquire device locks on suspend, Alan Stern, (Thu Jan 10, 10:04 am)