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authorChristian Eggers2020-10-12 10:39:42 +0200
committerJakub Kicinski2020-10-12 10:00:24 -0700
commit8098bd69bc4e925070313b1b95d03510f4f24738 (patch)
tree4e2741d3e0eb26f18a612ba95bab6dbe6d746a51 /drivers
parent874fb9e2ca949b443cc419a4f2227cafd4381d39 (diff)
net: dsa: microchip: fix race condition
Between queuing the delayed work and finishing the setup of the dsa ports, the process may sleep in request_module() (via phy_device_create()) and the queued work may be executed prior to the switch net devices being registered. In ksz_mib_read_work(), a NULL dereference will happen within netof_carrier_ok(dp->slave). Not queuing the delayed work in ksz_init_mib_timer() makes things even worse because the work will now be queued for immediate execution (instead of 2000 ms) in ksz_mac_link_down() via dsa_port_link_register_of(). Call tree: ksz9477_i2c_probe() \--ksz9477_switch_register() \--ksz_switch_register() +--dsa_register_switch() | \--dsa_switch_probe() | \--dsa_tree_setup() | \--dsa_tree_setup_switches() | +--dsa_switch_setup() | | +--ksz9477_setup() | | | \--ksz_init_mib_timer() | | | |--/* Start the timer 2 seconds later. */ | | | \--schedule_delayed_work(&dev->mib_read, msecs_to_jiffies(2000)); | | \--__mdiobus_register() | | \--mdiobus_scan() | | \--get_phy_device() | | +--get_phy_id() | | \--phy_device_create() | | |--/* sleeping, ksz_mib_read_work() can be called meanwhile */ | | \--request_module() | | | \--dsa_port_setup() | +--/* Called for non-CPU ports */ | +--dsa_slave_create() | | +--/* Too late, ksz_mib_read_work() may be called beforehand */ | | \--port->slave = ... | ... | +--Called for CPU port */ | \--dsa_port_link_register_of() | \--ksz_mac_link_down() | +--/* mib_read must be initialized here */ | +--/* work is already scheduled, so it will be executed after 2000 ms */ | \--schedule_delayed_work(&dev->mib_read, 0); \-- /* here port->slave is setup properly, scheduling the delayed work should be safe */ Solution: 1. Do not queue (only initialize) delayed work in ksz_init_mib_timer(). 2. Only queue delayed work in ksz_mac_link_down() if init is completed. 3. Queue work once in ksz_switch_register(), after dsa_register_switch() has completed. Fixes: 7c6ff470aa86 ("net: dsa: microchip: add MIB counter reading support") Signed-off-by: Christian Eggers <ceggers@arri.de> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Vladimir Oltean <olteanv@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/dsa/microchip/ksz_common.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index c796d42730ba..e5f047129b15 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -103,14 +103,8 @@ void ksz_init_mib_timer(struct ksz_device *dev)
INIT_DELAYED_WORK(&dev->mib_read, ksz_mib_read_work);
- /* Read MIB counters every 30 seconds to avoid overflow. */
- dev->mib_read_interval = msecs_to_jiffies(30000);
-
for (i = 0; i < dev->mib_port_cnt; i++)
dev->dev_ops->port_init_cnt(dev, i);
-
- /* Start the timer 2 seconds later. */
- schedule_delayed_work(&dev->mib_read, msecs_to_jiffies(2000));
}
EXPORT_SYMBOL_GPL(ksz_init_mib_timer);
@@ -143,7 +137,9 @@ void ksz_mac_link_down(struct dsa_switch *ds, int port, unsigned int mode,
/* Read all MIB counters when the link is going down. */
p->read = true;
- schedule_delayed_work(&dev->mib_read, 0);
+ /* timer started */
+ if (dev->mib_read_interval)
+ schedule_delayed_work(&dev->mib_read, 0);
}
EXPORT_SYMBOL_GPL(ksz_mac_link_down);
@@ -450,6 +446,12 @@ int ksz_switch_register(struct ksz_device *dev,
return ret;
}
+ /* Read MIB counters every 30 seconds to avoid overflow. */
+ dev->mib_read_interval = msecs_to_jiffies(30000);
+
+ /* Start the MIB timer. */
+ schedule_delayed_work(&dev->mib_read, 0);
+
return 0;
}
EXPORT_SYMBOL(ksz_switch_register);