On Mon, Nov 18, 2002 at 05:34:20PM +0300, Samium Gromoff wrote:
> The possible problem is encountered in ehci-q.c and ehci-sched.c
> in 2.4.19-pre9 and in one occurence in ehci-q.c of 2.5.47.
>
> the offending pattern is the same in both files:
>
> if (!list_empty (qtd_list)) {
> -----------------------8<----------------------------------------------
> list_splice (qtd_list, &qh->qtd_list);
> qh_update (qh, list_entry (qtd_list->next, struct ehci_qtd, qtd\_list));
> -----------------------8<----------------------------------------------
> } else {
> qh->hw_qtd_next = qh->hw_alt_next = EHCI_LIST_END;
> }
>
>
> since list_splice() the qtd_list is diposed of its belongings and
> immediately in the next line we rely on qtd_list->next to point
> at an existing list_head.
>
> i haven`t noticed any locking out there, and i`m afraid of what
> could result from a preemption happening between these two lines.
Um, David, any thoughts about this?
thanks,
greg k-h
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This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:31 EST