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blkcg: skip blkg printing if q isn't associated with disk

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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>
This commit is contained in:
Vivek Goyal 2012-03-05 13:15:10 -08:00 committed by Jens Axboe
parent 7a4dd281ec
commit 92616b5b3a
1 changed files with 14 additions and 3 deletions
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17
block/blk-cgroup.c
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@ -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,