Messages in this thread | | | Date | Sun, 24 Feb 2008 21:21:50 -0500 (EST) | From | Alan Stern <> | Subject | Re: [Bug 10030] Suspend doesn't work when SD card is inserted |
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On Sun, 24 Feb 2008, Rafael J. Wysocki wrote:
> > Very subtly wrong ;-). > > > > imagine suspending_task == 0xabcdef01. Now task "R" with current == > > 0xabcd0000 reads suspending_task while the other cpu is writing to it, > > and sees 0xabcd0000 (0xef01 was not yet written) -- and mistakenly > > believes that "R" == suspending_task. > > > > I agree it is very unlikely, and it will not happen on i386. But what > > about just using atomic_t suspending_task, and store current->pid into > > it? > > I'd rather use a lock, frankly. For example, we can require the readers to > take pm_sleep_rwsem for reading in order to access that.
That certainly won't work. Imagine what would happen when the reader _was_ the suspending task.
But if you really twist my arm, I'll go along with Pavel's suggestion.
Alan Stern
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