Messages in this thread | | | Date | Wed, 28 Jan 2009 18:12:05 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 2/3] work_on_cpu: Use our own workqueue. |
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On Thu, 29 Jan 2009 12:13:32 +1030 Rusty Russell <rusty@rustcorp.com.au> wrote:
> On Thursday 29 January 2009 06:14:40 Andrew Morton wrote: > > It's vulnerable to the same deadlock, I think? Suppose we have: > ... > > - A calls work_on_cpu() and takes woc_mutex. > > > > - Before function_which_takes_L() has started to execute, task B takes L > > then calls work_on_cpu() and task B blocks on woc_mutex. > > > > - Now function_which_takes_L() runs, and blocks on L > > Agreed, but now it's a fairly simple case. Both sides have to take lock L, and both have to call work_on_cpu. > > Workqueues are more generic and widespread, and an amazing amount of stuff gets called from them. That's why I felt uncomfortable with removing the one known problematic caller. >
hm. it's a bit of a timebomb.
y'know, the original way in which acpi-cpufreq did this is starting to look attractive. Migrate self to that CPU then just call the dang function. Slow, but no deadlocks (I think)?
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