linux-kernel - [PATCH 3/3] wifi: ath11k: mark ath11k_wow_convert_8023_to

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Message-ID: <20241119-ath11k-noinline-v1-3-4ec0a8aa30b2@quicinc.com>
Date: Tue, 19 Nov 2024 07:47:40 -0800
From: Jeff Johnson <quic_jjohnson@...cinc.com>
To: Kalle Valo <kvalo@...nel.org>, Jeff Johnson <jjohnson@...nel.org>,
        "Nathan
 Chancellor" <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Bill Wendling <morbo@...gle.com>,
        Justin Stitt <justinstitt@...gle.com>,
        "Arnd Bergmann" <arnd@...nel.org>
CC: <linux-wireless@...r.kernel.org>, <ath11k@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <llvm@...ts.linux.dev>,
        Jeff Johnson
	<quic_jjohnson@...cinc.com>
Subject: [PATCH 3/3] wifi: ath11k: mark ath11k_wow_convert_8023_to_80211()
 as noinline

When compiling the ath11k driver using clang with KASAN enabled, the
following warning is observed:

drivers/net/wireless/ath/ath11k/wow.c:672:5: warning: stack frame size (1336) exceeds limit (1024) in 'ath11k_wow_op_suspend' [-Wframe-larger-than]

This is similar to the issue found in ath12k/qmi.c that was discussed
in [1] and fixed with [2]. The issue is that clang inlining can
explode stack usage.

ath11k_wow_op_suspend() itself is a pretty lightweight function, but
it dispatches to several other functions which do the real work. One
path in particular is:

ath11k_wow_op_suspend()
	ath11k_wow_set_wakeups()
		ath11k_vif_wow_set_wakeups()
			ath11k_wow_convert_8023_to_80211()

Of these, ath11k_wow_convert_8023_to_80211() has non-trivial stack
usage, so mark it as 'noinline_for_stack' to prevent it from being
inlined in ath11k_wow_op_suspend(), thereby eliminating the excessive
stack usage.

Link: https://msgid.link/bc214795-1c51-4cb7-922f-67d6ef98bff2@quicinc.com # [1]
Link: https://patch.msgid.link/20241028-ath12k_qmi_driver_event_work-v1-1-0d532eb593fa@quicinc.com # [2]
Signed-off-by: Jeff Johnson <quic_jjohnson@...cinc.com>
---
 drivers/net/wireless/ath/ath11k/wow.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/wow.c b/drivers/net/wireless/ath/ath11k/wow.c
index 827085a926b2..b6f08755129f 100644
--- a/drivers/net/wireless/ath/ath11k/wow.c
+++ b/drivers/net/wireless/ath/ath11k/wow.c
@@ -148,8 +148,10 @@ static int ath11k_wow_cleanup(struct ath11k *ar)
  * 802.11: |4B|dest mac(6B)| 6B |src mac(6B)|  8B  |type(2B)|  body...  |
  *         +--+------------+----+-----------+---------------+-----------+
  */
-static void ath11k_wow_convert_8023_to_80211(struct cfg80211_pkt_pattern *new,
-					     const struct cfg80211_pkt_pattern *old)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+void ath11k_wow_convert_8023_to_80211(struct cfg80211_pkt_pattern *new,
+				      const struct cfg80211_pkt_pattern *old)
 {
 	u8 hdr_8023_pattern[ETH_HLEN] = {};
 	u8 hdr_8023_bit_mask[ETH_HLEN] = {};

-- 
2.42.0