diff options
| author | Jens Axboe <axboe@fb.com> | 2015-06-19 10:19:36 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-06-19 10:19:36 -0600 |
| commit | 9470e4a693db84bee7becbba8de01af02bb23c9f (patch) | |
| tree | 9267bd9cd8d882e8996ba5b2df80ac4277909519 | |
| parent | 4ceab71b9d84e55b59a76b54b2999dc377aae6e6 (diff) | |
| download | lwn-9470e4a693db84bee7becbba8de01af02bb23c9f.tar.gz lwn-9470e4a693db84bee7becbba8de01af02bb23c9f.zip | |
cfq-iosched: fix sysfs oops when attempting to read unconfigured weights
If none of the devices in the system are using CFQ, then attempting to
read:
/sys/fs/cgroup/blkio/blkio.leaf_weight
will results in a NULL dereference. Check for a valid cfq_group_data
struct before attempting to dereference it.
Reported-by: Andrey Wagin <avagin@gmail.com>
Fixes: e48453c3 ("block, cgroup: implement policy-specific per-blkcg data")
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | block/cfq-iosched.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index dbd0207928fb..ed86fb242cd4 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1714,16 +1714,26 @@ static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v) static int cfq_print_weight(struct seq_file *sf, void *v) { struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); + struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg); + unsigned int val = 0; - seq_printf(sf, "%u\n", blkcg_to_cfqgd(blkcg)->weight); + if (cgd) + val = cgd->weight; + + seq_printf(sf, "%u\n", val); return 0; } static int cfq_print_leaf_weight(struct seq_file *sf, void *v) { struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); + struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg); + unsigned int val = 0; + + if (cgd) + val = cgd->leaf_weight; - seq_printf(sf, "%u\n", blkcg_to_cfqgd(blkcg)->leaf_weight); + seq_printf(sf, "%u\n", val); return 0; } |