soc: qcom: aoss: Format string in qmp_send()

The majority of callers to qmp_send() composes the message dynamically
using some form of sprintf(), resulting in unnecessary complication and
stack usage.

By changing the interface of qmp_send() to take a format string and
arguments, the duplicated composition of the commands can be moved to a
single location.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Link: https://lore.kernel.org/r/20230811205839.727373-4-quic_bjorande@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

Author: quic-bjorande

drivers/soc/qcom/qcom_aoss.c

@@ -205,27 +205,33 @@ static bool qmp_message_empty(struct qmp *qmp)
 /**
  * qmp_send() - send a message to the AOSS
  * @qmp: qmp context
- * @data: message to be sent
+ * @fmt: format string for message to be sent
+ * @...: arguments for the format string
  *
- * Transmit @data to AOSS and wait for the AOSS to acknowledge the message.
+ * Transmit message to AOSS and wait for the AOSS to acknowledge the message.
  * data must not be longer than the mailbox size. Access is synchronized by
  * this implementation.
  *
  * Return: 0 on success, negative errno on failure
  */
-int qmp_send(struct qmp *qmp, const void *data)
+int qmp_send(struct qmp *qmp, const char *fmt, ...)
 {
 	char buf[QMP_MSG_LEN];
 	long time_left;
+	va_list args;
+	int len;
 	int ret;
 
-	if (WARN_ON(IS_ERR_OR_NULL(qmp) || !data))
+	if (WARN_ON(IS_ERR_OR_NULL(qmp) || !fmt))
 		return -EINVAL;
 
-	if (WARN_ON(strlen(data) >= sizeof(buf)))
-		return -EINVAL;
+	memset(buf, 0, sizeof(buf));
+	va_start(args, fmt);
+	len = vsnprintf(buf, sizeof(buf), fmt, args);
+	va_end(args);
 
-	strscpy_pad(buf, data, sizeof(buf));
+	if (WARN_ON(len >= sizeof(buf)))
+		return -EINVAL;
 
 	mutex_lock(&qmp->tx_lock);
 

include/linux/soc/qcom/qcom_aoss.h

@@ -13,13 +13,13 @@ struct qmp;
 
 #if IS_ENABLED(CONFIG_QCOM_AOSS_QMP)
 
-int qmp_send(struct qmp *qmp, const void *data);
+int qmp_send(struct qmp *qmp, const char *fmt, ...);
 struct qmp *qmp_get(struct device *dev);
 void qmp_put(struct qmp *qmp);
 
 #else
 
-static inline int qmp_send(struct qmp *qmp, const void *data)
+static inline int qmp_send(struct qmp *qmp, const char *fmt, ...)
 {
 	return -ENODEV;
 }