diff options
author | Christian Eggers <ceggers@arri.de> | 2020-10-12 10:39:42 +0200 |
---|---|---|
committer | Jakub Kicinski <kuba@kernel.org> | 2020-10-12 10:00:24 -0700 |
commit | 8098bd69bc4e925070313b1b95d03510f4f24738 (patch) | |
tree | 4e2741d3e0eb26f18a612ba95bab6dbe6d746a51 | |
parent | 874fb9e2ca949b443cc419a4f2227cafd4381d39 (diff) | |
download | linux-8098bd69bc4e925070313b1b95d03510f4f24738.tar.bz2 |
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>
-rw-r--r-- | drivers/net/dsa/microchip/ksz_common.c | 16 |
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); |