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Subject[PATCH] net: stmmac: don't attach interface until resume finishes
Date
Commit 14b41a2959fb ("net: stmmac: Delete txtimer in suspend") was the
first attempt to fix a race between mod_timer() and setup_timer()
during stmmac_resume(). However the issue still exists as the commit
only addressed half of the issue.

Same race can still happen as stmmac_resume() re-attaches interface
way too early - even before hardware is fully initialized. Worse,
doing so allows network traffic to restart and stmmac_tx_timer_arm()
being called in the middle of stmmac_resume(), which re-init tx timers
in stmmac_init_coalesce(). timer_list will be corrupted and system
crashes as a result of race between mod_timer() and setup_timer().

systemd--1995 2.... 552950018us : stmmac_suspend: 4994
ksoftirq-9 0..s2 553123133us : stmmac_tx_timer_arm: 2276
systemd--1995 0.... 553127896us : stmmac_resume: 5101
systemd--320 7...2 553132752us : stmmac_tx_timer_arm: 2276
(sd-exec-1999 5...2 553135204us : stmmac_tx_timer_arm: 2276
---------------------------------
pc : run_timer_softirq+0x468/0x5e0
lr : run_timer_softirq+0x570/0x5e0
Call trace:
run_timer_softirq+0x468/0x5e0
__do_softirq+0x124/0x398
irq_exit+0xd8/0xe0
__handle_domain_irq+0x6c/0xc0
gic_handle_irq+0x60/0xb0
el1_irq+0xb8/0x180
arch_cpu_idle+0x38/0x230
default_idle_call+0x24/0x3c
do_idle+0x1e0/0x2b8
cpu_startup_entry+0x28/0x48
secondary_start_kernel+0x1b4/0x208

Fix this by deferring netif_device_attach() to the end of
stmmac_resume().

Signed-off-by: Leon Yu <leoyu@nvidia.com>
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index a999d6b33a64..1f319c9cee46 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5190,8 +5190,6 @@ int stmmac_resume(struct device *dev)
return ret;
}

- netif_device_attach(ndev);
-
mutex_lock(&priv->lock);

stmmac_reset_queues_param(priv);
@@ -5218,6 +5216,8 @@ int stmmac_resume(struct device *dev)

phylink_mac_change(priv->phylink, true);

+ netif_device_attach(ndev);
+
return 0;
}
EXPORT_SYMBOL_GPL(stmmac_resume);
--
2.7.4
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