[PATCH v2 2/3] fs: tftp: print message when stack can't keep us with TFTP windowsize

Ahmad Fatoum a.fatoum at pengutronix.de
Thu Feb 2 05:34:14 PST 2023

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


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 at pengutronix.de>
v1 -> v2:
  - reword commit and warning message to point finger at
    network stack (Michael)
 fs/tftp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/tftp.c b/fs/tftp.c
index 0b0b86a1a07e..a63b133caa25 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. */
+		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.

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