linux-kernel - Re: [net] Revert "net: wwan: mhi_wwan_mbim: Avoid -Wflex-array-member-not-at-end warning"

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Message-ID: <1228d107-4a60-4c33-a763-1a199c0b0961@embeddedor.com>
Date: Tue, 20 Jan 2026 16:51:57 +0900
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Slark Xiao <slark_xiao@....com>, loic.poulain@....qualcomm.com,
 ryazanov.s.a@...il.com, johannes@...solutions.net, andrew+netdev@...n.ch,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, gustavoars@...nel.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [net] Revert "net: wwan: mhi_wwan_mbim: Avoid
 -Wflex-array-member-not-at-end warning"

Hi Slark,

On 1/20/26 16:20, Slark Xiao wrote:
> This reverts commit eeecf5d3a3a484cedfa3f2f87e6d51a7390ed960.
> 
> This change lead to MHI WWAN device can't connect to internet.
> I found a netwrok issue with kernel 6.19-rc4, but network works
> well with kernel 6.18-rc1. After checking, this commit is the
> root cause.

Thanks for the report.

Could you please apply the following patch on top of this revert,
and let us know if the problem still manifests? Thank you!

diff --git a/drivers/net/wwan/mhi_wwan_mbim.c b/drivers/net/wwan/mhi_wwan_mbim.c
index 1d7e3ad900c1..a271a72fed63 100644
--- a/drivers/net/wwan/mhi_wwan_mbim.c
+++ b/drivers/net/wwan/mhi_wwan_mbim.c
@@ -78,9 +78,12 @@ struct mhi_mbim_context {

  struct mbim_tx_hdr {
         struct usb_cdc_ncm_nth16 nth16;
-       struct usb_cdc_ncm_ndp16 ndp16;
-       struct usb_cdc_ncm_dpe16 dpe16[2];
+       __TRAILING_OVERLAP(struct usb_cdc_ncm_ndp16, ndp16, dpe16, __packed,
+               struct usb_cdc_ncm_dpe16 dpe16[2];
+       );
  } __packed;
+static_assert(offsetof(struct mbim_tx_hdr, ndp16.dpe16) ==
+             offsetof(struct mbim_tx_hdr, dpe16));

  static struct mhi_mbim_link *mhi_mbim_get_link_rcu(struct mhi_mbim_context *mbim,
                                                    unsigned int session)