[PATCH 5.19 278/717] eth: alx: take rtnl_lock on resume

Greg Kroah-Hartman
2022-10-22T08:17:26Z

From: Jakub Kicinski <kuba@kernel.org>

[ 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@gmail.com>
Reviewed-by: Niels Dossche <dossche.niels@gmail.com>
Link: https://lore.kernel.org/r/20220928181236.1053043-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/atheros/alx/main.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/atheros/alx/main.c b/drivers/net/ethernet/atheros/alx/main.c
index a89b93cb4e26..d5939586c82e 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;
}

--
2.35.1