Patch "eth: alx: take rtnl_lock on resume" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    eth: alx: take rtnl_lock on resume

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     eth-alx-take-rtnl_lock-on-resume.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ecaaea6b76fe67db78057166a895c5065d9675dd
Author: Jakub Kicinski <kuba@xxxxxxxxxx>
Date:   Wed Sep 28 11:12:36 2022 -0700

    eth: alx: take rtnl_lock on resume
    
    [ Upstream commit 6ad1c94e1e7e374d88f0cfd77936dddb8339aaba ]
    
    Zbynek reports that alx trips an rtnl assertion on resume:
    
     RTNL: assertion failed at net/core/dev.c (2891)
     RIP: 0010:netif_set_real_num_tx_queues+0x1ac/0x1c0
     Call Trace:
      <TASK>
      __alx_open+0x230/0x570 [alx]
      alx_resume+0x54/0x80 [alx]
      ? pci_legacy_resume+0x80/0x80
      dpm_run_callback+0x4a/0x150
      device_resume+0x8b/0x190
      async_resume+0x19/0x30
      async_run_entry_fn+0x30/0x130
      process_one_work+0x1e5/0x3b0
    
    indeed the driver does not hold rtnl_lock during its internal close
    and re-open functions during suspend/resume. Note that this is not
    a huge bug as the driver implements its own locking, and does not
    implement changing the number of queues, but we need to silence
    the splat.
    
    Fixes: 4a5fe57e7751 ("alx: use fine-grained locking instead of RTNL")
    Reported-and-tested-by: Zbynek Michl <zbynek.michl@xxxxxxxxx>
    Reviewed-by: Niels Dossche <dossche.niels@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20220928181236.1053043-1-kuba@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/atheros/alx/main.c b/drivers/net/ethernet/atheros/alx/main.c
index 98a8698a3201..2ac5253ff89a 100644
--- a/drivers/net/ethernet/atheros/alx/main.c
+++ b/drivers/net/ethernet/atheros/alx/main.c
@@ -1912,11 +1912,14 @@ static int alx_suspend(struct device *dev)
 
 	if (!netif_running(alx->dev))
 		return 0;
+
+	rtnl_lock();
 	netif_device_detach(alx->dev);
 
 	mutex_lock(&alx->mtx);
 	__alx_stop(alx);
 	mutex_unlock(&alx->mtx);
+	rtnl_unlock();
 
 	return 0;
 }
@@ -1927,6 +1930,7 @@ static int alx_resume(struct device *dev)
 	struct alx_hw *hw = &alx->hw;
 	int err;
 
+	rtnl_lock();
 	mutex_lock(&alx->mtx);
 	alx_reset_phy(hw);
 
@@ -1943,6 +1947,7 @@ static int alx_resume(struct device *dev)
 
 unlock:
 	mutex_unlock(&alx->mtx);
+	rtnl_unlock();
 	return err;
 }