On 08/21, Tero Kristo wrote: > In some cases, clocks can switch their parent with clk_set_rate, for > example clk_mux can do this in some cases. Current implementation of > clk_change_rate uses un-safe list iteration on the clock children, which > will cause wrong clocks to be parsed in case any of the clock children > change their parents during the change rate operation. Fixed by using > the safe list iterator instead. > > The problem was detected due to some divide by zero errors generated > by clock init on dra7-evm board, see discussion under > http://article.gmane.org/gmane.linux.ports.arm.kernel/349180 for details. > > Signed-off-by: Tero Kristo <t-kristo@xxxxxx> > To: Mike Turquette <mturquette@xxxxxxxxxx> > Reported-by: Nishanth Menon <nm@xxxxxx> > --- > drivers/clk/clk.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index b76fa69..bacc06f 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -1467,6 +1467,7 @@ static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long even > static void clk_change_rate(struct clk *clk) > { > struct clk *child; > + struct hlist_node *tmp; > unsigned long old_rate; > unsigned long best_parent_rate = 0; > bool skip_set_rate = false; > @@ -1502,7 +1503,11 @@ static void clk_change_rate(struct clk *clk) > if (clk->notifier_count && old_rate != clk->rate) > __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate); > > - hlist_for_each_entry(child, &clk->children, child_node) { > + /* > + * Use safe iteration, as change_rate can actually swap parents > + * for certain clock types. > + */ > + hlist_for_each_entry_safe(child, tmp, &clk->children, child_node) { > /* Skip children who will be reparented to another clock */ > if (child->new_parent && child->new_parent != clk) > continue; Are we not hitting the new_parent check here? I don't understand how we can be changing parents here unless the check is being avoided, in which case I wonder why determine_rate isn't being used. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
