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rtc: Avoid a couple of -Wflex-array-member-not-at-end warnings

PATCH Superseded Gustavo A. R. Silva 3 participants 3 messages Mar 14, 2025

Subsystems (2)
Real time clock (RTC) ChromeOS EC subdrivers

v1 of 2 Superseded Latest is v2 →

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Gustavo A. R. Silva

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#0 lore raw

PATCH 1/1 rtc: Avoid a couple of -Wflex-array-member-not-at-end warnings

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are getting ready to enable it, globally.

Use the DEFINE_RAW_FLEX() helper for an on-stack definition of a flexible structure where the size of the flexible-array member is known at compile-time, and refactor the rest of the code, accordingly.

So, with these changes, fix the following warnings:

drivers/rtc/rtc-cros-ec.c:62:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] drivers/rtc/rtc-cros-ec.c:40:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/rtc/rtc-cros-ec.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)
drivers/rtc/rtc-cros-ec.c +12 -18
index 865c2e82c7a5..9144bc12e0b7 100644
@@ -35,21 +35,18 @@ struct cros_ec_rtc {
 static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
 			   u32 *response)
 {
+	DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+			sizeof(struct ec_response_rtc));
 	int ret;
-	struct {
-		struct cros_ec_command msg;
-		struct ec_response_rtc data;
-	} __packed msg;
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg.command = command;
-	msg.msg.insize = sizeof(msg.data);
+	msg->command = command;
+	msg->insize = sizeof(struct ec_response_rtc);
 
-	ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
+	ret = cros_ec_cmd_xfer_status(cros_ec, msg);
 	if (ret < 0)
 		return ret;
 
-	*response = msg.data.time;
+	memcpy(response, msg->data, sizeof(*response));
 
 	return 0;
 }

@@ -57,18 +54,15 @@ static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
 static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
 			   u32 param)
 {
+	DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+			sizeof(struct ec_response_rtc));
 	int ret;
-	struct {
-		struct cros_ec_command msg;
-		struct ec_response_rtc data;
-	} __packed msg;
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg.command = command;
-	msg.msg.outsize = sizeof(msg.data);
-	msg.data.time = param;
+	msg->command = command;
+	msg->outsize = sizeof(struct ec_response_rtc);
+	memcpy(msg->data, &param, sizeof(param));
 
-	ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
+	ret = cros_ec_cmd_xfer_status(cros_ec, msg);
 	if (ret < 0)
 		return ret;
 	return 0;
Signature · 1 line
2.43.0
#1 lore raw
Quoted 14 lines · Gustavo A. R. Silva

static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,

drivers/rtc/rtc-cros-ec.c +2 -7
 			   u32 *response)
 {
+	DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+			sizeof(struct ec_response_rtc));
 	int ret;
-	struct {
-		struct cros_ec_command msg;
-		struct ec_response_rtc data;
-	} __packed msg;
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg.command = command;
-	msg.msg.insize = sizeof(msg.data);

drivers/rtc/rtc-cros-ec.c struct cros_ec_rtc { · line 49

Quoted 10 lines
drivers/rtc/rtc-cros-ec.c +4 -2
+	msg->command = command;
+	msg->insize = sizeof(struct ec_response_rtc);
 
-	ret = cros_ec_cmd_xfer_status(cros_ec, &msg.msg);
+	ret = cros_ec_cmd_xfer_status(cros_ec, msg);
 	if (ret < 0)
 		return ret;
 
-	*response = msg.data.time;
+	memcpy(response, msg->data, sizeof(*response));

Technically they are the same as struct ec_response_rtc only has an u32 member. Any reason to not translate it something similar to:

*response = ((struct ec_response_rtc *)msg->data)->time;

Quoted 12 lines
drivers/rtc/rtc-cros-ec.c +2 -2
 	return 0;
 }

@@ -57,18 +54,15 @@ static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
 static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
 			   u32 param)
 {
+	DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+			sizeof(struct ec_response_rtc));
 	int ret;
-	struct {
-		struct cros_ec_command msg;

drivers/rtc/rtc-cros-ec.c static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command, · line 63

Quoted 10 lines
drivers/rtc/rtc-cros-ec.c +3 -6
-		struct ec_response_rtc data;
-	} __packed msg;
 
-	memset(&msg, 0, sizeof(msg));
-	msg.msg.command = command;
-	msg.msg.outsize = sizeof(msg.data);
-	msg.data.time = param;
+	msg->command = command;
+	msg->outsize = sizeof(struct ec_response_rtc);
+	memcpy(msg->data, &param, sizeof(param));

Same here, how about:

((struct ec_response_rtc *)msg->data)->time = param;