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Commit 92616b5b authored by Vivek Goyal's avatar Vivek Goyal Committed by Jens Axboe
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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: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7a4dd281

block/blk-cgroup.c

+14 −3
Original line number Diff line number Diff line
@@ -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,