Messages in this thread | | | Date | Thu, 09 Feb 2006 16:08:04 -0500 | From | martin rogers <> | Subject | Help with 2.6.10 concurrency issue |
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All, I need help with a concurrency issue on 2.6.10. CONFIG_PREEMPT not set, but my code must run on both uni and SMP systems.
I have a function, that runs from a tastlet:
void readlist(unsigned long arg) { int flags; my_type *entry, *n;
if (list_empty(&mylist.list)) return; list_for_each_entry_safe(entry, n, &mylist.list, list) { spin_lock_irqsave(&mylock, flags); // protect against intr list_del(&entry->list); spin_unlock_irqrestore(&mylock, flags); INIT_LIST_HEAD(&entry->list); do_stuff(entry); } }
And the func that puts things on the list:
void writeList(my_type *record) { spin_lock(&mylock); list_add_tail(&record->list, &mylist.list); spin_unlock(&mylock); tasklet_schedule(&mytasklet.tlet); }
Problem is, the function writeList can be called from a H/W intr, and a workqueue (and that intr could of course happen while either the workqueue or the tasklet is running, right?).
If I use spin_lock_irqsave in writeList, it protects against the intr but not the tasklet. If I use spin_lock_bh, I don't get protection from the intr I think; plus, I get :
Badness in local_bh_enable at kernel/softirq.c:142
when the intr runs (what does this mean?).
So, how can I protect my data (my list) from both intrs (calling writeList) and the tasklet (calling readList) while the workqueue is inside of writeList? Combination of spin_lock_irqsave and local_bh_disable inside writeList ?
Thanks to all, Martin Rogers Wind River
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