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SubjectRe: [PATCH 4.19 540/639] wcn36xx: use dynamic allocation for large variables
Hi!

> From: Arnd Bergmann <arnd@arndb.de>
>
> [ Upstream commit 355cf31912014e6ff1bb1019ae4858cad12c68cf ]
>
> clang triggers a warning about oversized stack frames that gcc does not
> notice because of slightly different inlining decisions:
>
> ath/wcn36xx/smd.c:1409:5: error: stack frame size of 1040 bytes in function 'wcn36xx_smd_config_bss' [-Werror,-Wframe-larger-than=]
> ath/wcn36xx/smd.c:640:5: error: stack frame size of 1032 bytes in function 'wcn36xx_smd_start_hw_scan' [-Werror,-Wframe-larger-than=]
>
> Basically the wcn36xx_hal_start_scan_offload_req_msg,
> wcn36xx_hal_config_bss_req_msg_v1, and wcn36xx_hal_config_bss_req_msg
> structures are too large to be put on the kernel stack, but small
> enough that gcc does not warn about them.
>
> Use kzalloc() to allocate them all. There are similar structures in other
> parts of this driver, but they are all smaller, with the next largest
> stack frame at 480 bytes for wcn36xx_smd_send_beacon.

> int ret, i;
>
> if (req->ie_len > WCN36XX_MAX_SCAN_IE_LEN)
> return -EINVAL;
>
> mutex_lock(&wcn->hal_mutex);
> - INIT_HAL_MSG(msg_body, WCN36XX_HAL_START_SCAN_OFFLOAD_REQ);
> + msg_body = kzalloc(sizeof(*msg_body), GFP_KERNEL);
> + if (!msg_body) {
> + ret = -ENOMEM;
> + goto out;
> + }

The allocation can be done outside the lock.

> @@ -1410,16 +1428,21 @@ int wcn36xx_smd_config_bss(struct wcn36xx *wcn, struct ieee80211_vif *vif,
> struct ieee80211_sta *sta, const u8 *bssid,
> bool update)
> {
> - struct wcn36xx_hal_config_bss_req_msg msg;
> + struct wcn36xx_hal_config_bss_req_msg *msg;
> struct wcn36xx_hal_config_bss_params *bss;
> struct wcn36xx_hal_config_sta_params *sta_params;
> struct wcn36xx_vif *vif_priv = wcn36xx_vif_to_priv(vif);
> int ret;
>
> mutex_lock(&wcn->hal_mutex);
> - INIT_HAL_MSG(msg, WCN36XX_HAL_CONFIG_BSS_REQ);
> + msg = kzalloc(sizeof(*msg), GFP_KERNEL);
> + if (!msg) {
> + ret = -ENOMEM;
> + goto out;
> + }
> + INIT_HAL_MSG((*msg), WCN36XX_HAL_CONFIG_BSS_REQ);

Same here.

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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