aboutsummaryrefslogtreecommitdiffstats
path: root/block
diff options
context:
space:
mode:
authorVivek Goyal <vgoyal@redhat.com>2012-03-05 13:15:10 -0800
committerJens Axboe <axboe@kernel.dk>2012-03-06 21:27:22 +0100
commit92616b5b3a7c7fa8148df82e7ff6183056f2bfc8 (patch)
treeb204b7df4753e9508cf15d278688dc9c307761fa /block
parentblkcg: kill the mind-bending blkg->dev (diff)
downloadlinux-dev-92616b5b3a7c7fa8148df82e7ff6183056f2bfc8.tar.xz
linux-dev-92616b5b3a7c7fa8148df82e7ff6183056f2bfc8.zip
blkcg: skip blkg printing if q isn't associated with disk
blk-cgroup printing code currently assumes that there is a device/disk associated with every queue in the system, but modules like floppy, can instantiate request queues without registering disk which can lead to oops. Skip the queue/blkg which don't have dev/disk associated with them. -tj: Factored out backing_dev_info check into blkg_dev_name(). Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-cgroup.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 8742af3be84b..76942360872b 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -951,13 +951,24 @@ static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
return ret;
}
+static const char *blkg_dev_name(struct blkio_group *blkg)
+{
+ /* some drivers (floppy) instantiate a queue w/o disk registered */
+ if (blkg->q->backing_dev_info.dev)
+ return dev_name(blkg->q->backing_dev_info.dev);
+ return NULL;
+}
+
static void blkio_print_group_conf(struct cftype *cft, struct blkio_group *blkg,
struct seq_file *m)
{
- const char *dname = dev_name(blkg->q->backing_dev_info.dev);
+ const char *dname = blkg_dev_name(blkg);
int fileid = BLKIOFILE_ATTR(cft->private);
int rw = WRITE;
+ if (!dname)
+ return;
+
switch (blkg->plid) {
case BLKIO_POLICY_PROP:
if (blkg->conf.weight)
@@ -1049,9 +1060,9 @@ static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
rcu_read_lock();
hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
- const char *dname = dev_name(blkg->q->backing_dev_info.dev);
+ const char *dname = blkg_dev_name(blkg);
- if (BLKIOFILE_POLICY(cft->private) != blkg->plid)
+ if (!dname || BLKIOFILE_POLICY(cft->private) != blkg->plid)
continue;
if (pcpu)
cgroup_total += blkio_get_stat_cpu(blkg, cb, dname,