linux-kernel - [PATCH RT 3/5] net: phy: fixed

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Date:   Fri, 21 Aug 2020 14:47:02 -0500
From:   zanussi@...nel.org
To:     LKML <linux-kernel@...r.kernel.org>,
        linux-rt-users <linux-rt-users@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        John Kacur <jkacur@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Daniel Wagner <wagi@...om.org>,
        Clark Williams <williams@...hat.com>,
        Pavel Machek <pavel@...x.de>, Tom Zanussi <zanussi@...nel.org>
Cc:     "Ahmed S. Darwish" <a.darwish@...utronix.de>,
        "David S . Miller" <davem@...emloft.net>
Subject: [PATCH RT 3/5] net: phy: fixed_phy: Remove unused seqcount

From: "Ahmed S. Darwish" <a.darwish@...utronix.de>

v4.19.135-rt61-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


[ Upstream commit 6554eac9ef2bd1c968886b31cc7266b49258a463 ]

Commit bf7afb29d545 ("phy: improve safety of fixed-phy MII register
reading") protected the fixed PHY status with a sequence counter.

Two years later, commit d2b977939b18 ("net: phy: fixed-phy: remove
fixed_phy_update_state()") removed the sequence counter's write side
critical section -- neutralizing its read side retry loop.

Remove the unused seqcount.

Signed-off-by: Ahmed S. Darwish <a.darwish@...utronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: David S. Miller <davem@...emloft.net>
(cherry picked from v5.8-rc1 commit 79cbb6bc3332da7162c2581e151659ab8ebaa528)
Signed-off-by: Ahmed S. Darwish <a.darwish@...utronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Tom Zanussi <zanussi@...nel.org>
---
 drivers/net/phy/fixed_phy.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/net/phy/fixed_phy.c b/drivers/net/phy/fixed_phy.c
index 59820164502e..953ff54dd5df 100644
--- a/drivers/net/phy/fixed_phy.c
+++ b/drivers/net/phy/fixed_phy.c
@@ -23,7 +23,6 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/gpio.h>
-#include <linux/seqlock.h>
 #include <linux/idr.h>
 
 #include "swphy.h"
@@ -36,7 +35,6 @@ struct fixed_mdio_bus {
 struct fixed_phy {
 	int addr;
 	struct phy_device *phydev;
-	seqcount_t seqcount;
 	struct fixed_phy_status status;
 	int (*link_update)(struct net_device *, struct fixed_phy_status *);
 	struct list_head node;
@@ -62,18 +60,15 @@ static int fixed_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
 	list_for_each_entry(fp, &fmb->phys, node) {
 		if (fp->addr == phy_addr) {
 			struct fixed_phy_status state;
-			int s;
-
-			do {
-				s = read_seqcount_begin(&fp->seqcount);
-				/* Issue callback if user registered it. */
-				if (fp->link_update)
-					fp->link_update(fp->phydev->attached_dev,
-							&fp->status);
-				/* Check the GPIO for change in status */
-				fixed_phy_update(fp);
-				state = fp->status;
-			} while (read_seqcount_retry(&fp->seqcount, s));
+
+			/* Issue callback if user registered it. */
+			if (fp->link_update)
+				fp->link_update(fp->phydev->attached_dev,
+						&fp->status);
+
+			/* Check the GPIO for change in status */
+			fixed_phy_update(fp);
+			state = fp->status;
 
 			return swphy_read_reg(reg_num, &state);
 		}
@@ -131,8 +126,6 @@ int fixed_phy_add(unsigned int irq, int phy_addr,
 	if (!fp)
 		return -ENOMEM;
 
-	seqcount_init(&fp->seqcount);
-
 	if (irq != PHY_POLL)
 		fmb->mii_bus->irq[phy_addr] = irq;
 
-- 
2.17.1