diff options
| author | Vivek Goyal <vgoyal@redhat.com> | 2012-03-05 13:15:10 -0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-03-06 21:27:22 +0100 |
| commit | 92616b5b3a7c7fa8148df82e7ff6183056f2bfc8 (patch) | |
| tree | b204b7df4753e9508cf15d278688dc9c307761fa | |
| parent | 7a4dd281ec66224f802093962d1d903d86b09560 (diff) | |
| download | linux-92616b5b3a7c7fa8148df82e7ff6183056f2bfc8.tar.gz | |
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>
| -rw-r--r-- | block/blk-cgroup.c | 17 |
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, |