Re: [RFC PATCH v5 2/6] i2c: add helpers to ease DMA handling

quoted

quoted

+/**
+ * i2c_release_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg
+ * @msg: the message to be synced with
+ * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.
+ */
+void i2c_release_dma_safe_msg_buf(struct i2c_msg *msg, u8 *buf)
+{
+	if (!buf || buf == msg->buf)
+		return;
+
+	if (msg->flags & I2C_M_RD)
+		memcpy(msg->buf, buf, msg->len);
+
+	kfree(buf);

Only free when you actually allocated it.  Seems to me like you need
to check if (!(msg->flags & I2C_M_DMA_SAFE)) before kfree.

Otherwise the logic to do this will be needed in every driver
which will get irritating fast.

Well, I return early if (buf == msg->buf) which is only true for
I2C_M_DMA_SAFE. If not, I allocated the buffer. Am I missing something?
It would be very strange to call this function if the caller allocated
the buffer manually.

Thanks for the review!