RE: [PATCH] net: intel: e1000e: fix possible sleep-in-atomic-context bugs in e1000e_get_hw_semaphore()

[Brown, Aaron F]

> From: netdev-owner@xxxxxxxxxxxxxxx <netdev-owner@xxxxxxxxxxxxxxx>
> On Behalf Of Jia-Ju Bai
> Sent: Wednesday, December 18, 2019 6:17 AM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@xxxxxxxxx>; davem@xxxxxxxxxxxxx
> Cc: intel-wired-lan@xxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
> Subject: [PATCH] net: intel: e1000e: fix possible sleep-in-atomic-context bugs
> in e1000e_get_hw_semaphore()
> 
> The driver may sleep while holding a spinlock.
> The function call path (from bottom to top) in Linux 4.19 is:
> 
> drivers/net/ethernet/intel/e1000e/mac.c, 1366:
> 	usleep_range in e1000e_get_hw_semaphore
> drivers/net/ethernet/intel/e1000e/80003es2lan.c, 322:
> 	e1000e_get_hw_semaphore in
> e1000_release_swfw_sync_80003es2lan
> drivers/net/ethernet/intel/e1000e/80003es2lan.c, 197:
> 	e1000_release_swfw_sync_80003es2lan in
> e1000_release_phy_80003es2lan
> drivers/net/ethernet/intel/e1000e/netdev.c, 4883:
> 	(FUNC_PTR) e1000_release_phy_80003es2lan in
> e1000e_update_phy_stats
> drivers/net/ethernet/intel/e1000e/netdev.c, 4917:
> 	e1000e_update_phy_stats in e1000e_update_stats
> drivers/net/ethernet/intel/e1000e/netdev.c, 5945:
> 	e1000e_update_stats in e1000e_get_stats64
> drivers/net/ethernet/intel/e1000e/netdev.c, 5944:
> 	spin_lock in e1000e_get_stats64
> 
> drivers/net/ethernet/intel/e1000e/mac.c, 1384:
> 	usleep_range in e1000e_get_hw_semaphore
> drivers/net/ethernet/intel/e1000e/80003es2lan.c, 322:
> 	e1000e_get_hw_semaphore in
> e1000_release_swfw_sync_80003es2lan
> drivers/net/ethernet/intel/e1000e/80003es2lan.c, 197:
> 	e1000_release_swfw_sync_80003es2lan in
> e1000_release_phy_80003es2lan
> drivers/net/ethernet/intel/e1000e/netdev.c, 4883:
> 	(FUNC_PTR) e1000_release_phy_80003es2lan in
> e1000e_update_phy_stats
> drivers/net/ethernet/intel/e1000e/netdev.c, 4917:
> 	e1000e_update_phy_stats in e1000e_update_stats
> drivers/net/ethernet/intel/e1000e/netdev.c, 5945:
> 	e1000e_update_stats in e1000e_get_stats64
> drivers/net/ethernet/intel/e1000e/netdev.c, 5944:
> 	spin_lock in e1000e_get_stats64
> 
> (FUNC_PTR) means a function pointer is called.
> 
> To fix these bugs, usleep_range() is replaced with udelay().
> 
> These bugs are found by a static analysis tool STCheck written by myself.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/e1000e/mac.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Tested-by: Aaron Brown <aaron.f.brown@xxxxxxxxx>