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93 lines
2.7 KiB
93 lines
2.7 KiB
8 years ago
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From c36739c3cfd277a4cc9820a29dd0f4b7fbac795b Mon Sep 17 00:00:00 2001
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From: Russell King <rmk+kernel@arm.linux.org.uk>
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Date: Sun, 20 Sep 2015 18:31:36 +0100
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Subject: [PATCH 713/744] phy: improve safety of fixed-phy MII register reading
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There is no prevention of a concurrent call to both fixed_mdio_read()
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and fixed_phy_update_state(), which can result in the state being
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modified while it's being inspected. Fix this by using a seqcount
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to detect modifications, and memcpy()ing the state.
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We remain slightly naughty here, calling link_update() and updating
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the link status within the read-side loop - which would need rework
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of the design to change.
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Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
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Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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---
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drivers/net/phy/fixed_phy.c | 28 +++++++++++++++++++++-------
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1 file changed, 21 insertions(+), 7 deletions(-)
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--- a/drivers/net/phy/fixed_phy.c
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+++ b/drivers/net/phy/fixed_phy.c
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@@ -23,6 +23,7 @@
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#include <linux/slab.h>
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#include <linux/of.h>
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#include <linux/gpio.h>
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+#include <linux/seqlock.h>
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#include "swphy.h"
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@@ -35,6 +36,7 @@ struct fixed_mdio_bus {
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struct fixed_phy {
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int addr;
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struct phy_device *phydev;
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+ seqcount_t seqcount;
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struct fixed_phy_status status;
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int (*link_update)(struct net_device *, struct fixed_phy_status *);
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struct list_head node;
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@@ -59,13 +61,21 @@ static int fixed_mdio_read(struct mii_bu
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list_for_each_entry(fp, &fmb->phys, node) {
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if (fp->addr == phy_addr) {
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- /* Issue callback if user registered it. */
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- if (fp->link_update) {
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- fp->link_update(fp->phydev->attached_dev,
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- &fp->status);
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- fixed_phy_update(fp);
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- }
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- return swphy_read_reg(reg_num, &fp->status);
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+ struct fixed_phy_status state;
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+ int s;
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+
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+ do {
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+ s = read_seqcount_begin(&fp->seqcount);
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+ /* Issue callback if user registered it. */
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+ if (fp->link_update) {
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+ fp->link_update(fp->phydev->attached_dev,
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+ &fp->status);
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+ fixed_phy_update(fp);
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+ }
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+ state = fp->status;
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+ } while (read_seqcount_retry(&fp->seqcount, s));
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+
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+ return swphy_read_reg(reg_num, &state);
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}
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}
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@@ -117,6 +127,7 @@ int fixed_phy_update_state(struct phy_de
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list_for_each_entry(fp, &fmb->phys, node) {
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if (fp->addr == phydev->addr) {
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+ write_seqcount_begin(&fp->seqcount);
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#define _UPD(x) if (changed->x) \
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fp->status.x = status->x
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_UPD(link);
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@@ -126,6 +137,7 @@ int fixed_phy_update_state(struct phy_de
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_UPD(asym_pause);
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#undef _UPD
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fixed_phy_update(fp);
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+ write_seqcount_end(&fp->seqcount);
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return 0;
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}
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}
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@@ -150,6 +162,8 @@ int fixed_phy_add(unsigned int irq, int
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if (!fp)
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return -ENOMEM;
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+ seqcount_init(&fp->seqcount);
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+
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fmb->irqs[phy_addr] = irq;
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fp->addr = phy_addr;
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