diff options
| author | Peter Oberparleiter <oberpar@linux.vnet.ibm.com> | 2013-11-26 14:59:21 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-12-16 14:37:42 +0100 |
| commit | 47d30674d6c79197fa7bfb0d09d5857f61e0277b (patch) | |
| tree | 97e100ae386becbf98bdf892ca1cc137ea90f634 | |
| parent | 175746eb06a8925274558793814d8c802dc48276 (diff) | |
| download | linux-47d30674d6c79197fa7bfb0d09d5857f61e0277b.tar.bz2 | |
s390/css: Prevent unnecessary allocation in subchannel loop
Subchannel looping function for_each_subchannel_staged() allocates a
subchannel-ID-bitmap to efficiently iterate over the list of known
and unknown subchannels. Since this function is also used to iterate
over known-subchannels only, optimize that case by not requiring the
ID-bitmap allocation and falling back to simple bus_for_each_dev()
looping.
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | drivers/s390/cio/css.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 604333ebf01e..0268e5fd59b5 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -69,7 +69,8 @@ static int call_fn_known_sch(struct device *dev, void *data) struct cb_data *cb = data; int rc = 0; - idset_sch_del(cb->set, sch->schid); + if (cb->set) + idset_sch_del(cb->set, sch->schid); if (cb->fn_known_sch) rc = cb->fn_known_sch(sch, cb->data); return rc; @@ -115,6 +116,13 @@ int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *), cb.fn_known_sch = fn_known; cb.fn_unknown_sch = fn_unknown; + if (fn_known && !fn_unknown) { + /* Skip idset allocation in case of known-only loop. */ + cb.set = NULL; + return bus_for_each_dev(&css_bus_type, NULL, &cb, + call_fn_known_sch); + } + cb.set = idset_sch_new(); if (!cb.set) /* fall back to brute force scanning in case of oom */ |