Received-SPF: pass (google.com: domain of linux-wireless+bounces-749-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Jeff Johnson <quic_jjohnson@quicinc.com>
Date: Wed, 13 Dec 2023 09:06:39 -0800
Subject: [PATCH 1/6] wifi: ath10k: use flexible array in struct
 wmi_host_mem_chunks
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-ID: <20231213-wmi_host_mem_chunks_flexarray-v1-1-92922d92fa2c@quicinc.com>
References: <20231213-wmi_host_mem_chunks_flexarray-v1-0-92922d92fa2c@quicinc.com>
In-Reply-To: <20231213-wmi_host_mem_chunks_flexarray-v1-0-92922d92fa2c@quicinc.com>
To: Kalle Valo <kvalo@kernel.org>, Jeff Johnson <quic_jjohnson@quicinc.com>
CC: Kees Cook <keescook@chromium.org>,
        "Gustavo A. R. Silva"
	<gustavo@embeddedor.com>,
        <ath10k@lists.infradead.org>, <linux-wireless@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>

Currently struct wmi_host_mem_chunks defines:
	struct host_memory_chunk items[1];

Per the guidance in [1] this should be a flexible array. However there
is a documented requirement:
	some fw revisions require at least 1 chunk regardless of count

To satisfy this requirement, follow the guidance from [2] and wrap the
array in a union which contains both the flexible array and a single
instance of the underlying struct. Since the footprint of the struct
is unchanged, no additional driver changes are required.

No functional changes, compile tested only.

[1] https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays
[2] https://lore.kernel.org/linux-wireless/202308301529.AC90A9EF98@keescook/

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
---
 drivers/net/wireless/ath/ath10k/wmi.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/wmi.h b/drivers/net/wireless/ath/ath10k/wmi.h
index 9146df98fcee..833ce0251a2c 100644
--- a/drivers/net/wireless/ath/ath10k/wmi.h
+++ b/drivers/net/wireless/ath/ath10k/wmi.h
@@ -3069,7 +3069,10 @@ struct host_memory_chunk {
 struct wmi_host_mem_chunks {
 	__le32 count;
 	/* some fw revisions require at least 1 chunk regardless of count */
-	struct host_memory_chunk items[1];
+	union {
+		struct host_memory_chunk item;
+		DECLARE_FLEX_ARRAY(struct host_memory_chunk, items);
+	};
 } __packed;
 
 struct wmi_init_cmd {

-- 
2.42.0