[PATCH 3/5] nvme-tcp: fix I/O stalls on congested sockets

[Hannes Reinecke <hare@kernel.org>]

When the socket is busy processing nvme_tcp_try_recv() might
return -EAGAIN, but this doesn't automatically imply that
the sending side is blocked, too.
So check if there are pending requests once nvme_tcp_try_recv()
returns -EAGAIN and continue with the sending loop to avoid
I/O stalls.

Acked-by: Chris Leech <cleech@redhat.com>
Signed-off-by: Hannes Reinecke <hare@kernel.org>
---
 drivers/nvme/host/tcp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 1a319cb86453..87f1d7a4ea06 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1389,9 +1389,12 @@ static void nvme_tcp_io_work(struct work_struct *w)
 		result = nvme_tcp_try_recv(queue);
 		if (result > 0)
 			pending = true;
-		else if (unlikely(result < 0))
+		else if (unlikely(result < 0) && result != -EAGAIN)
 			return;
 
+		if (nvme_tcp_queue_has_pending(queue))
+			pending = true;
+
 		if (!pending || !queue->rd_enabled)
 			return;
 
-- 
2.35.3