backport commit ("c739b17a715c net: stmmac: don't attach interface until resume finishes") to linux-5.4-stable

Hi reviewers,

I suggest to backport 
commit "c739b17a715c net: stmmac: don't attach interface until resume finishes"
to linux-5.4 stable tree.

This patch fix resume issue by deferring netif_device_attach().

However, the patch cannot be cherry-pick directly on to stable-5.4.
A slightly change to the origin patch is required.
I'd like to provide the modification to stable-5.4 if it is needed.

commit: c739b17a715c6a850477189fb7c5f9a6af74f4bb
subject: net: stmmac: don't attach interface until resume finishes
kernel version to apply to: Linux-5.4

Thanks.
Macpaul Lin

On Mon, Sep 27, 2021 at 06:45:00PM +0800, Macpaul Lin wrote:

Hi reviewers,

I suggest to backport 
commit "c739b17a715c net: stmmac: don't attach interface until resume finishes"
to linux-5.4 stable tree.

I see no such commit id in Linus's kernel tree.

Are you sure you got the correct id?

thanks,

greg k-h

Hi reviewers,

I suggest to backport 
commit "31096c3e8b11 net: stmmac: don't attach interface until resume finishes"
to linux-5.4 stable tree.

This patch fix resume issue by deferring netif_device_attach().

However, the patch cannot be cherry-pick directly on to stable-5.4.
A slightly change to the origin patch is required.
I'd like to provide the modification to stable-5.4 if it is needed.

commit: 31096c3e8b1163c6e966bf4d1f36d8b699008f84
subject: net: stmmac: don't attach interface until resume finishes
kernel version to apply to: Linux-5.4

Sorry for that I've send a wrong commit hash which is in my working tree
previously.

Thanks.
Macpaul Lin

On Tue, Sep 28, 2021 at 03:43:49PM +0800, Macpaul Lin wrote:

Hi reviewers,

I suggest to backport 
commit "31096c3e8b11 net: stmmac: don't attach interface until resume finishes"
to linux-5.4 stable tree.

This patch fix resume issue by deferring netif_device_attach().

However, the patch cannot be cherry-pick directly on to stable-5.4.
A slightly change to the origin patch is required.
I'd like to provide the modification to stable-5.4 if it is needed.

Ok, can you please send a properly backported patch so that we can apply
it?

thanks,

greg k-h

From: Leon Yu <redacted>

commit 31096c3e8b1163c6e966bf4d1f36d8b699008f84 upstream.

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 <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 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 10d28be73f45..56d227b31dbd 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -4853,8 +4853,6 @@ int stmmac_resume(struct device *dev)
 			stmmac_mdio_reset(priv->mii);
 	}
 
-	netif_device_attach(ndev);
-
 	mutex_lock(&priv->lock);
 
 	stmmac_reset_queues_param(priv);

@@ -4878,6 +4876,8 @@ int stmmac_resume(struct device *dev)
 
 	phylink_mac_change(priv->phylink, true);
 
+	netif_device_attach(ndev);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(stmmac_resume);

-- 
2.18.0

On Tue, Sep 28, 2021 at 04:36:20PM +0800, Macpaul Lin wrote:

From: Leon Yu <redacted>

commit 31096c3e8b1163c6e966bf4d1f36d8b699008f84 upstream.

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 <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>

Whenever you forward on a patch, you should add yourself to the
signed-off-by chain.

I'll just add you to the cc: to let us know who asked for this patch.

thanks,

greg k-h