Messages in this thread | | | Date | Sat, 3 Jan 2004 11:00:55 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: [PATCH 1/2] kthread_create |
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On Fri, 2 Jan 2004, Davide Libenzi wrote:
> On Sat, 3 Jan 2004, Rusty Russell wrote: > > > In message <Pine.LNX.4.44.0401020856150.2278-100000@bigblue.dev.mdolabs.com> you write: > > > Rusty, you still have to use global static data when there is no need. > > > > And you're still putting obscure crap in the task struct when there's > > no need. Honestly, I'd be ashamed to post such a patch. > > Ashamed !? Take a look at your original patch and then define shame. You > had a communication mechanism that whilst being a private 1<->1 > communication among two tasks, relied on a single global message > strucure, lock and mutex. Honestly I do not like myself to add stuff > inside a strcture for one-time use. Not because of adding 12 bytes to the > struct, that are laughable. But because it is used by a small piece of > code w/out a re-use ability for other things.
Rusty, I took a better look at the patch and I think we can have per-kthread stuff w/out littering the task_struct and by making the thing more robust. We keep a global list_head protected by a global spinlock. We define a structure that contain all the per-kthread stuff we need (including a task_struct* to the kthread itself). When a kthread starts it will add itself to the list, and when it will die it will remove itself from the list. The start/stop functions will lookup the list (or hash, depending on how much stuff you want to drop in) with the target task_struct*, and if the lookup fails, it means the task already quit (another task already did kthread_stop() ??, natural death ????). This is too bad, but at least there won't be deadlock (or crash) beacause of this. This because currently we keep the kthread task_struct* lingering around w/out a method that willl inform us if the task goes away for some reason (so that we can avoid signaling it and waiting for some interaction). The list/hash will be able to tell us this. What do you think?
- Davide
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