Messages in this thread | | | From | Christophe Leroy <> | Subject | Re: [PATCH net-next 02/15] net: dsa: sja1105: Remove usage of iterator for list_add() after loop | Date | Fri, 8 Apr 2022 07:47:59 +0000 |
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Le 07/04/2022 à 12:28, Jakob Koschel a écrit : > In preparation to limit the scope of a list iterator to the list > traversal loop, use a dedicated pointer to point to the found element [1]. > > Before, the code implicitly used the head when no element was found > when using &pos->list. Since the new variable is only set if an > element was found, the list_add() is performed within the loop > and only done after the loop if it is done on the list head directly. > > Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] > Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com> > --- > drivers/net/dsa/sja1105/sja1105_vl.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c > index b7e95d60a6e4..cfcae4d19eef 100644 > --- a/drivers/net/dsa/sja1105/sja1105_vl.c > +++ b/drivers/net/dsa/sja1105/sja1105_vl.c > @@ -27,20 +27,24 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg, > if (list_empty(&gating_cfg->entries)) { > list_add(&e->list, &gating_cfg->entries); > } else { > - struct sja1105_gate_entry *p; > + struct sja1105_gate_entry *p = NULL, *iter; > > - list_for_each_entry(p, &gating_cfg->entries, list) { > - if (p->interval == e->interval) { > + list_for_each_entry(iter, &gating_cfg->entries, list) { > + if (iter->interval == e->interval) { > NL_SET_ERR_MSG_MOD(extack, > "Gate conflict"); > rc = -EBUSY; > goto err; > } > > - if (e->interval < p->interval) > + if (e->interval < iter->interval) { > + p = iter; > + list_add(&e->list, iter->list.prev); > break; > + } > } > - list_add(&e->list, p->list.prev); > + if (!p) > + list_add(&e->list, gating_cfg->entries.prev); > } > > gating_cfg->num_entries++;
This change looks ugly, why duplicating the list_add() to do the same ? At the end of the loop the pointer contains gating_cfg->entries, so it was cleaner before.
If you don't want to use the loop index outside the loop, fair enough, all you have to do is:
struct sja1105_gate_entry *p, *iter;
list_for_each_entry(iter, &gating_cfg->entries, list) { if (iter->interval == e->interval) { NL_SET_ERR_MSG_MOD(extack, "Gate conflict"); rc = -EBUSY; goto err; } p = iter;
if (e->interval < iter->interval) break; } list_add(&e->list, p->list.prev);
Christophe
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