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[PATCH] wifi: ath12k: mark QMI driver event helpers as noinline

Jeff Johnson posted 1 patch 3 weeks, 6 days ago 
drivers/net/wireless/ath/ath12k/qmi.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)
[PATCH] wifi: ath12k: mark QMI driver event helpers as noinline
Posted by Jeff Johnson 3 weeks, 6 days ago 
As described in [1], compiling the ath12k driver using clang with
KASAN enabled warns about some functions with excessive stack usage,
with the worst case being:

drivers/net/wireless/ath/ath12k/qmi.c:3546:13: warning: stack frame size (2456) exceeds limit (1024) in 'ath12k_qmi_driver_event_work' [-Wframe-larger-than]

Nathan [2] highlighted work done by Arnd [3] to address similar
issues in other portions of the kernel.

ath12k_qmi_driver_event_work() itself is a pretty lightweight
function, but it dispatches to several other functions which do the
real work:
ath12k_qmi_driver_event_work()
	ath12k_qmi_event_server_arrive()
		ath12k_qmi_host_cap_send()
	ath12k_qmi_event_mem_request()
		ath12k_qmi_respond_fw_mem_request()
	ath12k_qmi_event_load_bdf()
		ath12k_qmi_request_target_cap()
		ath12k_qmi_load_bdf_qmi()
		ath12k_qmi_wlanfw_m3_info_send()

Mark all of those underlying functions as 'noinline_for_stack' to
prevent them from being inlined in ath12k_qmi_driver_event_work(),
thereby eliminating the excessive stack usage.

Link: https://msgid.link/bc214795-1c51-4cb7-922f-67d6ef98bff2@quicinc.com # [1]
Link: https://msgid.link/20241025223321.GA3647469@thelio-3990X # [2]
Link: https://lore.kernel.org/all/?q=f:arnd@kernel.org+Wframe-larger-than # [3]
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
---
 drivers/net/wireless/ath/ath12k/qmi.c | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/qmi.c b/drivers/net/wireless/ath/ath12k/qmi.c
index b93ce9f87f61..d2d9d03c7a28 100644
--- a/drivers/net/wireless/ath/ath12k/qmi.c
+++ b/drivers/net/wireless/ath/ath12k/qmi.c
@@ -2066,7 +2066,9 @@ static void ath12k_host_cap_parse_mlo(struct ath12k_base *ab,
 	req->mlo_chip_info_valid = 1;
 }
 
-static int ath12k_qmi_host_cap_send(struct ath12k_base *ab)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_host_cap_send(struct ath12k_base *ab)
 {
 	struct qmi_wlanfw_host_cap_req_msg_v01 req = {};
 	struct qmi_wlanfw_host_cap_resp_msg_v01 resp = {};
@@ -2275,7 +2277,9 @@ static int ath12k_qmi_fw_ind_register_send(struct ath12k_base *ab)
 	return ret;
 }
 
-static int ath12k_qmi_respond_fw_mem_request(struct ath12k_base *ab)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_respond_fw_mem_request(struct ath12k_base *ab)
 {
 	struct qmi_wlanfw_respond_mem_req_msg_v01 *req;
 	struct qmi_wlanfw_respond_mem_resp_msg_v01 resp = {};
@@ -2433,7 +2437,9 @@ static int ath12k_qmi_alloc_target_mem_chunk(struct ath12k_base *ab)
 	return 0;
 }
 
-static int ath12k_qmi_request_target_cap(struct ath12k_base *ab)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_request_target_cap(struct ath12k_base *ab)
 {
 	struct qmi_wlanfw_cap_req_msg_v01 req = {};
 	struct qmi_wlanfw_cap_resp_msg_v01 resp = {};
@@ -2619,8 +2625,10 @@ static int ath12k_qmi_load_file_target_mem(struct ath12k_base *ab,
 	return ret;
 }
 
-static int ath12k_qmi_load_bdf_qmi(struct ath12k_base *ab,
-				   enum ath12k_qmi_bdf_type type)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_load_bdf_qmi(struct ath12k_base *ab,
+			    enum ath12k_qmi_bdf_type type)
 {
 	struct device *dev = ab->dev;
 	char filename[ATH12K_QMI_MAX_BDF_FILE_NAME_SIZE];
@@ -2791,7 +2799,9 @@ static int ath12k_qmi_m3_load(struct ath12k_base *ab)
 	return ret;
 }
 
-static int ath12k_qmi_wlanfw_m3_info_send(struct ath12k_base *ab)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_wlanfw_m3_info_send(struct ath12k_base *ab)
 {
 	struct m3_mem_region *m3_mem = &ab->qmi.m3_mem;
 	struct qmi_wlanfw_m3_info_req_msg_v01 req = {};
@@ -3079,7 +3089,9 @@ ath12k_qmi_driver_event_post(struct ath12k_qmi *qmi,
 	return 0;
 }
 
-static int ath12k_qmi_event_server_arrive(struct ath12k_qmi *qmi)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_event_server_arrive(struct ath12k_qmi *qmi)
 {
 	struct ath12k_base *ab = qmi->ab;
 	int ret;
@@ -3101,7 +3113,9 @@ static int ath12k_qmi_event_server_arrive(struct ath12k_qmi *qmi)
 	return ret;
 }
 
-static int ath12k_qmi_event_mem_request(struct ath12k_qmi *qmi)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_event_mem_request(struct ath12k_qmi *qmi)
 {
 	struct ath12k_base *ab = qmi->ab;
 	int ret;
@@ -3115,7 +3129,9 @@ static int ath12k_qmi_event_mem_request(struct ath12k_qmi *qmi)
 	return ret;
 }
 
-static int ath12k_qmi_event_load_bdf(struct ath12k_qmi *qmi)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath12k_qmi_event_load_bdf(struct ath12k_qmi *qmi)
 {
 	struct ath12k_base *ab = qmi->ab;
 	int ret;

---
base-commit: 8a58dcd8db9c7af1187f0236d71a99cbbe146f6a
change-id: 20241025-ath12k_qmi_driver_event_work-ea9703c44ad7
Re: [PATCH] wifi: ath12k: mark QMI driver event helpers as noinline
Posted by Jeff Johnson 2 weeks, 6 days ago 
On Mon, 28 Oct 2024 07:08:40 -0700, Jeff Johnson wrote:
> As described in [1], compiling the ath12k driver using clang with
> KASAN enabled warns about some functions with excessive stack usage,
> with the worst case being:
> 
> drivers/net/wireless/ath/ath12k/qmi.c:3546:13: warning: stack frame size (2456) exceeds limit (1024) in 'ath12k_qmi_driver_event_work' [-Wframe-larger-than]
> 
> Nathan [2] highlighted work done by Arnd [3] to address similar
> issues in other portions of the kernel.
> 
> [...]

Applied, thanks!

[1/1] wifi: ath12k: mark QMI driver event helpers as noinline
      commit: 07826419700d4e7429523bbb4e936df6bca19c5e

Best regards,
-- 
Jeff Johnson <quic_jjohnson@quicinc.com>
Re: [PATCH] wifi: ath12k: mark QMI driver event helpers as noinline
Posted by Kalle Valo 3 weeks, 3 days ago 
Jeff Johnson <quic_jjohnson@quicinc.com> writes:

> As described in [1], compiling the ath12k driver using clang with
> KASAN enabled warns about some functions with excessive stack usage,
> with the worst case being:
>
> drivers/net/wireless/ath/ath12k/qmi.c:3546:13: warning: stack frame size (2456) exceeds limit (1024) in 'ath12k_qmi_driver_event_work' [-Wframe-larger-than]
>
> Nathan [2] highlighted work done by Arnd [3] to address similar
> issues in other portions of the kernel.
>
> ath12k_qmi_driver_event_work() itself is a pretty lightweight
> function, but it dispatches to several other functions which do the
> real work:
> ath12k_qmi_driver_event_work()
> 	ath12k_qmi_event_server_arrive()
> 		ath12k_qmi_host_cap_send()
> 	ath12k_qmi_event_mem_request()
> 		ath12k_qmi_respond_fw_mem_request()
> 	ath12k_qmi_event_load_bdf()
> 		ath12k_qmi_request_target_cap()
> 		ath12k_qmi_load_bdf_qmi()
> 		ath12k_qmi_wlanfw_m3_info_send()
>
> Mark all of those underlying functions as 'noinline_for_stack' to
> prevent them from being inlined in ath12k_qmi_driver_event_work(),
> thereby eliminating the excessive stack usage.
>
> Link: https://msgid.link/bc214795-1c51-4cb7-922f-67d6ef98bff2@quicinc.com # [1]
> Link: https://msgid.link/20241025223321.GA3647469@thelio-3990X # [2]
> Link: https://lore.kernel.org/all/?q=f:arnd@kernel.org+Wframe-larger-than # [3]
> Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>

Acked-by: Kalle Valo <kvalo@kernel.org>

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