Re: [PATCH][next] leds: Avoid -Wflex-array-member-not-at-end warning
From: Gustavo A. R. Silva
Date: Fri Mar 28 2025 - 14:51:25 EST
Hi!
On 28/03/25 12:31, Thomas Weißschuh wrote:
Hi Gustavo,
On 2025-03-28 08:33:22-0600, Gustavo A. R. Silva wrote:
-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 warning:
drivers/leds/leds-cros_ec.c:70:40: 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 <gustavoars@xxxxxxxxxx>
---
drivers/leds/leds-cros_ec.c | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)
diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c
index 275522b81ea5..6eab0474f52d 100644
--- a/drivers/leds/leds-cros_ec.c
+++ b/drivers/leds/leds-cros_ec.c
@@ -66,24 +66,20 @@ static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec,
union cros_ec_led_cmd_data *arg)
{
int ret;
- struct {
- struct cros_ec_command msg;
- union cros_ec_led_cmd_data data;
- } __packed buf = {
- .msg = {
- .version = 1,
- .command = EC_CMD_LED_CONTROL,
- .insize = sizeof(arg->resp),
- .outsize = sizeof(arg->req),
- },
- .data.req = arg->req
- };
-
- ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg);
+ DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+ sizeof(union cros_ec_led_cmd_data));
+
+ msg->version = 1;
+ msg->command = EC_CMD_LED_CONTROL;
+ msg->insize = sizeof(arg->resp);
+ msg->outsize = sizeof(arg->req);
+ *(struct ec_params_led_control *)msg->data = arg->req;
To be honest this looks really ugly and it's not at all obvious what is
We can do something like this, instead:
diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c
index 275522b81ea5..c7235f4e577b 100644
--- a/drivers/leds/leds-cros_ec.c
+++ b/drivers/leds/leds-cros_ec.c
@@ -66,24 +66,24 @@ static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec,
union cros_ec_led_cmd_data *arg)
{
int ret;
- struct {
- struct cros_ec_command msg;
- union cros_ec_led_cmd_data data;
- } __packed buf = {
- .msg = {
- .version = 1,
- .command = EC_CMD_LED_CONTROL,
- .insize = sizeof(arg->resp),
- .outsize = sizeof(arg->req),
- },
- .data.req = arg->req
- };
-
- ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg);
+ DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
+ sizeof(union cros_ec_led_cmd_data));
+ struct ec_params_led_control *req =
+ (struct ec_params_led_control *)msg->data;
+ struct ec_response_led_control *resp =
+ (struct ec_response_led_control *)msg->data;
+
+ msg->version = 1;
+ msg->command = EC_CMD_LED_CONTROL;
+ msg->insize = sizeof(arg->resp);
+ msg->outsize = sizeof(arg->req);
+ *req = arg->req;
+
+ ret = cros_ec_cmd_xfer_status(cros_ec, msg);
if (ret < 0)
return ret;
- arg->resp = buf.data.resp;
+ arg->resp = *resp;
return 0;
}
as in other cases:
https://lore.kernel.org/linux-hardening/Z-a4meHAy-t58bcE@kspp/
-Gustavo
going on. We have the utility function cros_ec_cmd() which would be the
nicer alternative. (Without having verified that it avoids the warning).
While it is slightly more expensive, I don't think it matters.
And if it does, the helper can be optimized.
(The same goes for my other cros_ec drivers)
+
+ ret = cros_ec_cmd_xfer_status(cros_ec, msg);
if (ret < 0)
return ret;
- arg->resp = buf.data.resp;
+ arg->resp = *(struct ec_response_led_control *)msg->data;
return 0;
}
Thomas