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authorFelix Fietkau <nbd@nbd.name>2017-04-17 08:43:54 +0200
committerFelix Fietkau <nbd@nbd.name>2017-04-17 08:44:37 +0200
commit047695a0294fd7046ba45e5490156c2b8e936a81 (patch)
treede5072e74d685d2b4274b5bfce15d35230b73a05 /target/linux/mvebu/patches-4.4/124-phy-improve-safety-of-fixed-phy-MII-register-reading.patch
parentaefa195749c68aa21bf135a5ec944b91cabc47ca (diff)
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Revert "mvebu: remove linux 4.4 support"
This reverts commit 51397d7d95d9f5e210a5557f65de1fa21e6f5921. There are some unresolved random crashes on WRT1900AC v1 that still need to be sorted out Signed-off-by: Felix Fietkau <nbd@nbd.name>
Diffstat (limited to 'target/linux/mvebu/patches-4.4/124-phy-improve-safety-of-fixed-phy-MII-register-reading.patch')
-rw-r--r--target/linux/mvebu/patches-4.4/124-phy-improve-safety-of-fixed-phy-MII-register-reading.patch92
1 files changed, 92 insertions, 0 deletions
diff --git a/target/linux/mvebu/patches-4.4/124-phy-improve-safety-of-fixed-phy-MII-register-reading.patch b/target/linux/mvebu/patches-4.4/124-phy-improve-safety-of-fixed-phy-MII-register-reading.patch
new file mode 100644
index 0000000000..5167b07101
--- /dev/null
+++ b/target/linux/mvebu/patches-4.4/124-phy-improve-safety-of-fixed-phy-MII-register-reading.patch
@@ -0,0 +1,92 @@
+From c36739c3cfd277a4cc9820a29dd0f4b7fbac795b Mon Sep 17 00:00:00 2001
+From: Russell King <rmk+kernel@arm.linux.org.uk>
+Date: Sun, 20 Sep 2015 18:31:36 +0100
+Subject: [PATCH 713/744] phy: improve safety of fixed-phy MII register reading
+
+There is no prevention of a concurrent call to both fixed_mdio_read()
+and fixed_phy_update_state(), which can result in the state being
+modified while it's being inspected. Fix this by using a seqcount
+to detect modifications, and memcpy()ing the state.
+
+We remain slightly naughty here, calling link_update() and updating
+the link status within the read-side loop - which would need rework
+of the design to change.
+
+Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
+Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
+---
+ drivers/net/phy/fixed_phy.c | 28 +++++++++++++++++++++-------
+ 1 file changed, 21 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/phy/fixed_phy.c
++++ b/drivers/net/phy/fixed_phy.c
+@@ -23,6 +23,7 @@
+ #include <linux/slab.h>
+ #include <linux/of.h>
+ #include <linux/gpio.h>
++#include <linux/seqlock.h>
+
+ #include "swphy.h"
+
+@@ -35,6 +36,7 @@ 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;
+@@ -59,13 +61,21 @@ static int fixed_mdio_read(struct mii_bu
+
+ list_for_each_entry(fp, &fmb->phys, node) {
+ if (fp->addr == phy_addr) {
+- /* Issue callback if user registered it. */
+- if (fp->link_update) {
+- fp->link_update(fp->phydev->attached_dev,
+- &fp->status);
+- fixed_phy_update(fp);
+- }
+- return swphy_read_reg(reg_num, &fp->status);
++ 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);
++ fixed_phy_update(fp);
++ }
++ state = fp->status;
++ } while (read_seqcount_retry(&fp->seqcount, s));
++
++ return swphy_read_reg(reg_num, &state);
+ }
+ }
+
+@@ -117,6 +127,7 @@ int fixed_phy_update_state(struct phy_de
+
+ list_for_each_entry(fp, &fmb->phys, node) {
+ if (fp->addr == phydev->addr) {
++ write_seqcount_begin(&fp->seqcount);
+ #define _UPD(x) if (changed->x) \
+ fp->status.x = status->x
+ _UPD(link);
+@@ -126,6 +137,7 @@ int fixed_phy_update_state(struct phy_de
+ _UPD(asym_pause);
+ #undef _UPD
+ fixed_phy_update(fp);
++ write_seqcount_end(&fp->seqcount);
+ return 0;
+ }
+ }
+@@ -150,6 +162,8 @@ int fixed_phy_add(unsigned int irq, int
+ if (!fp)
+ return -ENOMEM;
+
++ seqcount_init(&fp->seqcount);
++
+ fmb->irqs[phy_addr] = irq;
+
+ fp->addr = phy_addr;