fs: tftp: print message when stack can't keep us with TFTP windowsize

When the NIC driver doesn't configure enough buffers to keep up
with a big TFTP windowsize, error reporting is less than optimal,
e.g. on AX88x72A

  T BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBT T BBBBBBBBBBBBT
  BBBBBBBBBBBBBBBBBBBBBBBBBT

or on older DWMAC1000 (non-EQOS):

  WARNING: eth0: Rx error status (8800)
  T BBBBBBWARNING: eth0: Rx error status (8800)

While we probably want to:

  - decrease rate limit in __net_poll()
  - increase ring buffer depth for affected drivers

For now, at least print a helpful warning.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20230202133415.319020-2-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/tftp.c b/fs/tftp.c
index 0b0b86a1a0..a63b133caa 100644
--- a/fs/tftp.c
+++ b/fs/tftp.c
@@ -477,6 +477,8 @@ static void tftp_handle_data(struct file_priv *priv, uint16_t block,
 		/* completely unexpected and unrelated to actual window;
 		   ignore the packet. */
 		printf("B");
+		if (g_tftp_window_size > 1)
+			pr_warn_once("Unexpected packet. global.tftp.windowsize set too high?\n");
 	} else {
 		/* The 'rc < 0' below happens e.g. when datagrams in the first
 		   part of the transfer window are dropped.