Re: [PATCH net-next v5 3/5] net: dsa: mxl862xx: add devlink flash_update and info_get

The switch leaves MCUboot on its own by booting the new image, but the
driver has no in-place path back, so it reinitialises with a full
device_reprobe() scheduled regardless of the transfer outcome -- after a
failure the switch is still in MCUboot and probe re-detects it. During
the teardown its API reads return -ENODEV and writes fake success, so it
neither stalls on the absent firmware nor consumes buffers it never
filled. The reprobe holds module and device references taken before the
switch was disturbed and runs from a heap work item, not a kernel
thread: remove() frees the devm-managed priv, and kthread_create() in
the devlink caller would return -EINTR on interrupt or trip the
hung-task watchdog while parked across the minute-long flash.

Just for my understanding....

The reprobe causes all the user point netdevs to be destroyed, and are
then recreated?

That seems like a good solution to the issue of all state information
has been lost in the switch.

+static int mxl862xx_sb_pdi_poll_stat(struct mxl862xx_priv *priv, u16 expected,
+				     unsigned long timeout_ms)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);
+	int ret;
+
+	do {
+		ret = mxl862xx_smdio_read(priv, MXL862XX_SB_PDI_STAT);
+		if (ret < 0)
+			return ret;
+		if ((u16)ret == expected)
+			return 0;
+		usleep_range(10000, 11000);
+	} while (time_before(jiffies, timeout));
+
+	return -ETIMEDOUT;

I suggest using iopoll.h. This code has the usual bug when rolling
your own.

+/* Post-flash reprobe. Runs from a self-contained heap work (not a kthread and
+ * not the devlink caller's context): kthread_create() in the caller context
+ * fails -EINTR if the devlink command was Ctrl-C'd, and schedule_work() cannot.

A English sentence should not finish with the word "cannot".

+	/* Failures from here on must go through end_magic so MCUboot
+	 * reboots instead of waiting forever.
+	 */
+	ret = mxl862xx_sb_pdi_poll_stat(priv, MXL862XX_SB_PDI_READY,
+					MXL862XX_FW_READY_TIMEOUT_MS);
+	if (ret) {
+		dev_err(&priv->mdiodev->dev,
+			"flash: bootloader not ready: %pe\n", ERR_PTR(ret));
+		return ret;

What about the comment above? end_magic?

     	   Andrew