[PATCH v2] io_uring: add napi busy settings to the fdinfo output

[Olivier Langlois <olivier@xxxxxxxxxxxxxx>]

this info may be useful when attempting to debug a problem
involving a ring using the feature.

Here is an example of the output:
ip-172-31-39-89 /proc/772/fdinfo # cat 14
pos:	0
flags:	02000002
mnt_id:	16
ino:	10243
SqMask:	0xff
SqHead:	633
SqTail:	633
CachedSqHead:	633
CqMask:	0x3fff
CqHead:	430250
CqTail:	430250
CachedCqTail:	430250
SQEs:	0
CQEs:	0
SqThread:	885
SqThreadCpu:	0
SqTotalTime:	52793826
SqWorkTime:	3590465
UserFiles:	0
UserBufs:	0
PollList:
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=6, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=6, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
CqOverflowList:
NAPI:	enabled
napi_busy_poll_to:	1
napi_prefer_busy_poll:	true

Signed-off-by: Olivier Langlois <olivier@xxxxxxxxxxxxxx>
---
 io_uring/fdinfo.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/io_uring/fdinfo.c b/io_uring/fdinfo.c
index b1e0e0d85349..05f5c8572ba4 100644
--- a/io_uring/fdinfo.c
+++ b/io_uring/fdinfo.c
@@ -221,7 +221,18 @@ __cold void io_uring_show_fdinfo(struct seq_file *m, struct file *file)
 			   cqe->user_data, cqe->res, cqe->flags);
 
 	}
-
 	spin_unlock(&ctx->completion_lock);
+#ifdef CONFIG_NET_RX_BUSY_POLL
+	if (ctx->napi_enabled) {
+		seq_puts(m, "NAPI:\tenabled\n");
+		seq_printf(m, "napi_busy_poll_dt:\t%llu\n", ctx->napi_busy_poll_dt);
+		if (ctx->napi_prefer_busy_poll)
+			seq_puts(m, "napi_prefer_busy_poll:\ttrue\n");
+		else
+			seq_puts(m, "napi_prefer_busy_poll:\tfalse\n");
+	} else {
+		seq_puts(m, "NAPI:\tdisabled\n");
+	}
+#endif
 }
 #endif
-- 
2.45.2