Re: [PATCH] Revert "net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends"

[Eric Dumazet <eric.dumazet@gmail.com>]

On 06/18/2018 11:45 AM, Mathieu Malaterre wrote:

> 
> Here is what I get on my side
> 
> [   53.628847] sungem: sungem wrong csum : 4e04/f97, len 64 bytes
> [   53.667063] sungem: sungem wrong csum : eea8/6eec, len 149 bytes
> [   58.648952] sungem: sungem wrong csum : 2095/3d06, len 64 bytes
> [   58.669414] sungem: sungem wrong csum : 5245/b50, len 149 bytes
> [   63.674451] sungem: sungem wrong csum : 2d8/5abd, len 149 bytes
> [   68.678233] sungem: sungem wrong csum : b8fc/a498, len 149 bytes
> [   73.685771] sungem: sungem wrong csum : 374/5a21, len 149 bytes
> [   78.689089] sungem: sungem wrong csum : d81/5014, len 149 bytes
> [   83.683261] sungem: sungem wrong csum : 4e04/f97, len 64 bytes
> [   83.690193] sungem: sungem wrong csum : c2f7/9a9d, len 149 bytes
> [   88.692511] sungem: sungem wrong csum : f4d8/68bc, len 149 bytes
> [   93.699915] sungem: sungem wrong csum : 1370/4a25, len 149 bytes
> [   98.703136] sungem: sungem wrong csum : e1b5/7bdf, len 149 bytes
> [  103.704230] sungem: sungem wrong csum : 5321/a74, len 149 bytes
> [  108.688912] sungem: sungem wrong csum : 2095/3d06, len 64 bytes
> [  108.706559] sungem: sungem wrong csum : ddbc/7fd8, len 149 bytes
> [  113.713189] sungem: sungem wrong csum : 5a65/330, len 149 bytes
> [  113.891697] sungem: sungem wrong csum : 4e04/f97, len 64 bytes
> [  118.717151] sungem: sungem wrong csum : f7c8/65cc, len 149 bytes
> [  123.722680] sungem: sungem wrong csum : 3d7a/201b, len 149 bytes
> [  128.726524] sungem: sungem wrong csum : c8fd/9497, len 149 bytes
> [  133.732045] sungem: sungem wrong csum : de0d/7f87, len 149 bytes
> [  135.529163] sungem: sungem wrong csum : 3089/b6dd, len 96 bytes
> [  135.529208] eth0: hw csum failure
> [  135.529220] CPU: 0 PID: 0 Comm: swapper Not tainted 4.17.0+ #7
> [  135.529226] Call Trace:
> [  135.529243] [dffedbe0] [c069ddac]
> __skb_checksum_complete+0xf0/0x108 (unreliable)

Thanks, then I guess next step would be to dump the content of the frames
having a wrong checksum, hoping we find an easy way to discard the CHECKSUM_COMPLETE
in a selective way.

Otherwise, we will need to remove CHECKSUM_COMPLETE setting in this driver.

diff --git a/drivers/net/ethernet/sun/sungem.c b/drivers/net/ethernet/sun/sungem.c
index 7a16d40a72d13cf1d522e8a3a396c826fe76f9b9..77a761f95be788bb86c8d917f613c9084818f826 100644
--- a/drivers/net/ethernet/sun/sungem.c
+++ b/drivers/net/ethernet/sun/sungem.c
@@ -857,6 +857,14 @@ static int gem_rx(struct gem *gp, int work_to_do)
 
                csum = (__force __sum16)htons((status & RXDCTRL_TCPCSUM) ^ 0xffff);
                skb->csum = csum_unfold(csum);
+               {
+               __wsum rsum = csum_partial(skb->data + ETH_HLEN, len - ETH_HLEN, 0);
+               if (csum != csum_fold(rsum) && net_ratelimit())
+                       pr_err("sungem wrong csum : %04x/%04x, len %u bytes\n",
+                               csum, csum_fold(rsum), len);
+                       print_hex_dump(KERN_ERR, "raw data: ", DUMP_PREFIX_OFFSET,
+                                           16, 1, skb->data, len, true);
+               }
                skb->ip_summed = CHECKSUM_COMPLETE;
                skb->protocol = eth_type_trans(skb, gp->dev);