[PATCH v2] wifi: rtw89: Correct immediate cfg_len calculation for scan_offload_be

[PATCH v2] wifi: rtw89: Correct immediate cfg_len calculation for scan_offload_be

[Liang Jie]

From: Liang Jie <liangjie@lixiang.com>

Ensures the correct calculation of `cfg_len` prior to the allocation of
the skb in the `rtw89_fw_h2c_scan_offload_be` function, particularly when
the `SCAN_OFFLOAD_BE_V0` firmware feature is enabled. It addresses an
issue where an incorrect skb size might be allocated due to a delayed
setting of `cfg_len`, potentially leading to memory inefficiencies.

By moving the conditional check and assignment of `cfg_len` before skb
allocation, the patch guarantees that `len`, which depends on `cfg_len`,
is accurately computed, ensuring proper skb size and preventing any
unnecessary memory reservation for firmware operations not supporting
beyond the `w8` member of the command data structure.

This correction helps to optimize memory usage and maintain consistent
behavior across different firmware versions.

Fixes: 6ca6b918f280 ("wifi: rtw89: 8922a: Add new fields for scan offload H2C command")
Signed-off-by: Liang Jie <liangjie@lixiang.com>
---

Changes in v2:
- Standardized the format of the commit log.
- Optimized the handling logic for cfg_len.
- Link to v1: https://lore.kernel.org/linux-wireless/20250109012356.1015198-1-buaajxlj@163.com/

 drivers/net/wireless/realtek/rtw89/fw.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
index 2191c037d72e..2be1bee724ca 100644
--- a/drivers/net/wireless/realtek/rtw89/fw.c
+++ b/drivers/net/wireless/realtek/rtw89/fw.c
@@ -5170,6 +5170,7 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
 	u8 opch_size = sizeof(*opch) * option->num_opch;
 	u8 probe_id[NUM_NL80211_BANDS];
 	u8 cfg_len = sizeof(*h2c);
+	u8 ver = U8_MAX;
 	unsigned int cond;
 	void *ptr;
 	int ret;
@@ -5178,6 +5179,11 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
 
 	rtw89_scan_get_6g_disabled_chan(rtwdev, option);
 
+	if (RTW89_CHK_FW_FEATURE(SCAN_OFFLOAD_BE_V0, &rtwdev->fw)) {
+		cfg_len = offsetofend(typeof(*h2c), w8);
+		ver = 0;
+	}
+
 	len = cfg_len + macc_role_size + opch_size;
 	skb = rtw89_fw_h2c_alloc_skb_with_hdr(rtwdev, len);
 	if (!skb) {
@@ -5246,10 +5252,8 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
 					   RTW89_H2C_SCANOFLD_BE_W8_PROBE_RATE_6GHZ);
 	}
 
-	if (RTW89_CHK_FW_FEATURE(SCAN_OFFLOAD_BE_V0, &rtwdev->fw)) {
-		cfg_len = offsetofend(typeof(*h2c), w8);
+	if (ver == 0)
 		goto flex_member;
-	}
 
 	h2c->w9 = le32_encode_bits(sizeof(*h2c) / sizeof(h2c->w0),
 				   RTW89_H2C_SCANOFLD_BE_W9_SIZE_CFG) |
-- 
2.25.1

RE: [PATCH v2] wifi: rtw89: Correct immediate cfg_len calculation for scan_offload_be

[Ping-Ke Shih]

Liang Jie <buaajxlj@163.com> wrote: 
> diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
> index 2191c037d72e..2be1bee724ca 100644
> --- a/drivers/net/wireless/realtek/rtw89/fw.c
> +++ b/drivers/net/wireless/realtek/rtw89/fw.c
> @@ -5170,6 +5170,7 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
>         u8 opch_size = sizeof(*opch) * option->num_opch;
>         u8 probe_id[NUM_NL80211_BANDS];
>         u8 cfg_len = sizeof(*h2c);
> +       u8 ver = U8_MAX;
>         unsigned int cond;
>         void *ptr;
>         int ret;

In reverse X'mas tree. Otherwise, looks good to me. 

RE: [PATCH v2] wifi: rtw89: Correct immediate cfg_len calculation for scan_offload_be

[Liang Jie]

On Thu, 9 Jan 2025 01:55:23 +0000, Ping-Ke Shih <pkshih@realtek.com> wrote:
> Liang Jie <buaajxlj@163.com> wrote: 
> > diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
> > index 2191c037d72e..2be1bee724ca 100644
> > --- a/drivers/net/wireless/realtek/rtw89/fw.c
> > +++ b/drivers/net/wireless/realtek/rtw89/fw.c
> > @@ -5170,6 +5170,7 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
> >         u8 opch_size = sizeof(*opch) * option->num_opch;
> >         u8 probe_id[NUM_NL80211_BANDS];
> >         u8 cfg_len = sizeof(*h2c);
> > +       u8 ver = U8_MAX;
> >         unsigned int cond;
> >         void *ptr;
> >         int ret;
> 
> In reverse X'mas tree. Otherwise, looks good to me. 

Thank you for pointing out the "In reverse X'mas tree" issue in the code structure.
I will address this and submit [PATCH v3] with the necessary corrections.

Best regards,
Liang Jie