Messages in this thread | | | Date | Tue, 24 Mar 1998 11:43:28 -0700 (MST) | From | Colin Plumb <> | Subject | Re: Modified floppies can crash Linux (fwd) |
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Something that might be helpful when fixing this:
A very efficient way to detect loops in a chain is to compare each element chain[i] with chain[j], where j is the largest power of 2 less than i.
E.g.
void traverse_linked_list(struct linked_list *p) { struct linked_list *bookmark = NULL; unsigned counter = 0;
while (p && p != bookmark) { process_node(p); counter++; if (!(counter & (counter-1)) /* Is counter a power of 2? */ bookmark = p; p = p->next; } if (p) { /* We have processed part of the chain twice, but * at least we can escape the loop. */ printk("Bad chain, aborting traversal."); } }
Hacking this into kernel code is left as an exercise for the reader... -- -Colin
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