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7a4dd28)
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>
+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)
{
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;
int fileid = BLKIOFILE_ATTR(cft->private);
int rw = WRITE;
+ if (!dname)
+ return;
+
switch (blkg->plid) {
case BLKIO_POLICY_PROP:
if (blkg->conf.weight)
switch (blkg->plid) {
case BLKIO_POLICY_PROP:
if (blkg->conf.weight)
rcu_read_lock();
hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
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,
continue;
if (pcpu)
cgroup_total += blkio_get_stat_cpu(blkg, cb, dname,