| Message ID | 20250313115235.3707600-4-nilay@linux.ibm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | block: protect debugfs attributes using elavtor_lock | expand |
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index 1c958bbaddce..3421b5521fe2 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -347,9 +347,14 @@ static int hctx_busy_show(void *data, struct seq_file *m) { struct blk_mq_hw_ctx *hctx = data; struct show_busy_params params = { .m = m, .hctx = hctx }; + int res; + res = mutex_lock_interruptible(&hctx->queue->elevator_lock); + if (res) + return res; blk_mq_tagset_busy_iter(hctx->queue->tag_set, hctx_show_busy_rq, ¶ms); + mutex_unlock(&hctx->queue->elevator_lock); return 0; }
The hctx_busy_show method in debugfs is currently unprotected. This method iterates over all started requests in a tagset and prints them. However, the tags can be updated concurrently via the sysfs attributes 'nr_requests' or 'scheduler' (elevator switch), leading to potential race conditions. Since sysfs attributes 'nr_requests' and 'scheduler' are already protected using q->elevator_lock, extend this protection to the debugfs 'busy' attribute as well to ensure consistency. Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> --- block/blk-mq-debugfs.c | 5 +++++ 1 file changed, 5 insertions(+)