On Tue, Jan 24, 2017 at 02:25:39PM +0100, Hannes Reinecke wrote:

On 01/23/2017 07:59 PM, Omar Sandoval wrote:

quoted

From: Omar Sandoval <redacted>

hctx->state could come in handy for bugs where the hardware queue gets
stuck in the stopped state, and hctx->flags is just useful to know.

Signed-off-by: Omar Sandoval <redacted>
---
 block/blk-mq-debugfs.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

Hehe. I've found myself adding exactly the same attributes when
debugging mq-deadline :-)

quoted

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 01711bbf5ade..0c14511fa9e0 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c

@@ -29,7 +29,49 @@ struct blk_mq_debugfs_attr {
 
 static struct dentry *block_debugfs_root;
 
+static int hctx_state_show(struct seq_file *m, void *v)
+{
+	struct blk_mq_hw_ctx *hctx = m->private;
+
+	seq_printf(m, "0x%lx\n", hctx->state);
+	return 0;
+}
+

What about decoding it?
Would make life so much easier, and one doesn't have to have a kernel
source tree available when looking things up...

I thought of this, too, but doing that would require setting up a
mapping from flag values to strings and keeping those in sync with the
actual flags, which I don't think is worth the trouble, since I imagine
that most of the time you're going to be consulting the source to debug
this kind of issue, anyways.

Thanks for the review!