From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Sun, 10 Nov 2019 14:07:14 +0000
Subject: net: sfp: track upstream's attachment state in state machine
Patch-mainline: v5.5-rc1
Git-commit: 6b0da5c9c1a39eeead9c75eef3a0f2f62c375b2f
References: bsc#1154353

Track the upstream's attachment state in the state machine rather than
maintaining a boolean, which ensures that we have a strict order of
ATTACH followed by an UP event - we can never believe that a newly
attached upstream will be anything but down.

Rearrange the order of state machines so we run the module state
machine after the upstream device's state machine, so the module state
machine can check the current state of the device and take action to
e.g. reset back to empty state when the upstream is detached.

This is to allow the module detection to run independently of the
network device becoming available.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/phy/sfp.c |   42 +++++++++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 13 deletions(-)

--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -36,6 +36,8 @@ enum {
 
 	SFP_E_INSERT = 0,
 	SFP_E_REMOVE,
+	SFP_E_DEV_ATTACH,
+	SFP_E_DEV_DETACH,
 	SFP_E_DEV_DOWN,
 	SFP_E_DEV_UP,
 	SFP_E_TX_FAULT,
@@ -50,7 +52,8 @@ enum {
 	SFP_MOD_PRESENT,
 	SFP_MOD_ERROR,
 
-	SFP_DEV_DOWN = 0,
+	SFP_DEV_DETACHED = 0,
+	SFP_DEV_DOWN,
 	SFP_DEV_UP,
 
 	SFP_S_DOWN = 0,
@@ -80,6 +83,7 @@ static const char *mod_state_to_str(unsi
 }
 
 static const char * const dev_state_strings[] = {
+	[SFP_DEV_DETACHED] = "detached",
 	[SFP_DEV_DOWN] = "down",
 	[SFP_DEV_UP] = "up",
 };
@@ -94,6 +98,8 @@ static const char *dev_state_to_str(unsi
 static const char * const event_strings[] = {
 	[SFP_E_INSERT] = "insert",
 	[SFP_E_REMOVE] = "remove",
+	[SFP_E_DEV_ATTACH] = "dev_attach",
+	[SFP_E_DEV_DETACH] = "dev_detach",
 	[SFP_E_DEV_DOWN] = "dev_down",
 	[SFP_E_DEV_UP] = "dev_up",
 	[SFP_E_TX_FAULT] = "tx_fault",
@@ -188,7 +194,6 @@ struct sfp {
 	struct gpio_desc *gpio[GPIO_MAX];
 	int gpio_irq[GPIO_MAX];
 
-	bool attached;
 	struct mutex st_mutex;			/* Protects state */
 	unsigned int state;
 	struct delayed_work poll;
@@ -1496,17 +1501,26 @@ static void sfp_sm_mod_remove(struct sfp
 	dev_info(sfp->dev, "module removed\n");
 }
 
-/* This state machine tracks the netdev up/down state */
+/* This state machine tracks the upstream's state */
 static void sfp_sm_device(struct sfp *sfp, unsigned int event)
 {
 	switch (sfp->sm_dev_state) {
 	default:
-		if (event == SFP_E_DEV_UP)
+		if (event == SFP_E_DEV_ATTACH)
+			sfp->sm_dev_state = SFP_DEV_DOWN;
+		break;
+
+	case SFP_DEV_DOWN:
+		if (event == SFP_E_DEV_DETACH)
+			sfp->sm_dev_state = SFP_DEV_DETACHED;
+		else if (event == SFP_E_DEV_UP)
 			sfp->sm_dev_state = SFP_DEV_UP;
 		break;
 
 	case SFP_DEV_UP:
-		if (event == SFP_E_DEV_DOWN)
+		if (event == SFP_E_DEV_DETACH)
+			sfp->sm_dev_state = SFP_DEV_DETACHED;
+		else if (event == SFP_E_DEV_DOWN)
 			sfp->sm_dev_state = SFP_DEV_DOWN;
 		break;
 	}
@@ -1517,17 +1531,20 @@ static void sfp_sm_device(struct sfp *sf
  */
 static void sfp_sm_module(struct sfp *sfp, unsigned int event)
 {
-	/* Handle remove event globally, it resets this state machine */
-	if (event == SFP_E_REMOVE) {
+	/* Handle remove event globally, it resets this state machine.
+	 * Also deal with upstream detachment.
+	 */
+	if (event == SFP_E_REMOVE || sfp->sm_dev_state < SFP_DEV_DOWN) {
 		if (sfp->sm_mod_state > SFP_MOD_PROBE)
 			sfp_sm_mod_remove(sfp);
-		sfp_sm_mod_next(sfp, SFP_MOD_EMPTY, 0);
+		if (sfp->sm_mod_state != SFP_MOD_EMPTY)
+			sfp_sm_mod_next(sfp, SFP_MOD_EMPTY, 0);
 		return;
 	}
 
 	switch (sfp->sm_mod_state) {
 	default:
-		if (event == SFP_E_INSERT && sfp->attached)
+		if (event == SFP_E_INSERT)
 			sfp_sm_mod_next(sfp, SFP_MOD_PROBE, T_SERIAL);
 		break;
 
@@ -1693,8 +1710,8 @@ static void sfp_sm_event(struct sfp *sfp
 		sm_state_to_str(sfp->sm_state),
 		event_to_str(event));
 
-	sfp_sm_module(sfp, event);
 	sfp_sm_device(sfp, event);
+	sfp_sm_module(sfp, event);
 	sfp_sm_main(sfp, event);
 
 	dev_dbg(sfp->dev, "SM: exit %s:%s:%s\n",
@@ -1707,15 +1724,14 @@ static void sfp_sm_event(struct sfp *sfp
 
 static void sfp_attach(struct sfp *sfp)
 {
-	sfp->attached = true;
+	sfp_sm_event(sfp, SFP_E_DEV_ATTACH);
 	if (sfp->state & SFP_F_PRESENT)
 		sfp_sm_event(sfp, SFP_E_INSERT);
 }
 
 static void sfp_detach(struct sfp *sfp)
 {
-	sfp->attached = false;
-	sfp_sm_event(sfp, SFP_E_REMOVE);
+	sfp_sm_event(sfp, SFP_E_DEV_DETACH);
 }
 
 static void sfp_start(struct sfp *sfp)