From 2d04b9e856125197ec8e967471426d56ab7efcf0 Mon Sep 17 00:00:00 2001 From: Guinan Sun Date: Thu, 9 Jul 2020 08:00:31 +0000 Subject: [PATCH] net/ixgbe/base: fix infinite recursion on PCIe link down In some corner cases the functions ixgbe_clear_rar_generic and ixgbe_clear_vmdq_generic may call one another leading to infinite recursion. When ixgbe_clear_vmdq_generic is called with IXGBE_CLEAR_VMDQ_ALL flag, it's going to clear MPSAR registers, and proceed to call ixgbe_clear_rar_generic, which in turn will clear the RAR registers, and recursively call back ixgbe_clear_vmdq_generic. Normally, the latter would detect that MPSAR registers have already been cleared and terminate the recursion. However, when PCIe link is down, and before the driver has had the opportunity to shut itself down, all register reads return 0xFFFFFFFF, and all register writes fail silently. In such case, because ixgbe_clear_vmdq_generic blindly assumes that clearing MPSAR registers succeeded, it's going to always call ixgbe_clear_rar_generic, which in turn will always call back ixgbe_clear_vmdq_generic, creating infinite recursion. This patch re-reads MPSAR register values after they had been cleared. In case of PCIe link failure, the values read will be non-zero, which will terminate the recursion. On the other hand, under normal circumstances the value read from MPSAR registers is going to be equal to the value previously written, so this patch is expected not to cause any regressions. Fixes: af75078fece3 ("first public release") Cc: stable@dpdk.org Signed-off-by: Robert Konklewski Signed-off-by: Guinan Sun Reviewed-by: Wei Zhao --- drivers/net/ixgbe/base/ixgbe_common.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ixgbe/base/ixgbe_common.c b/drivers/net/ixgbe/base/ixgbe_common.c index fec6241f5b..2d848a02b3 100644 --- a/drivers/net/ixgbe/base/ixgbe_common.c +++ b/drivers/net/ixgbe/base/ixgbe_common.c @@ -3777,11 +3777,11 @@ s32 ixgbe_clear_vmdq_generic(struct ixgbe_hw *hw, u32 rar, u32 vmdq) if (vmdq == IXGBE_CLEAR_VMDQ_ALL) { if (mpsar_lo) { IXGBE_WRITE_REG(hw, IXGBE_MPSAR_LO(rar), 0); - mpsar_lo = 0; + mpsar_lo = IXGBE_READ_REG(hw, IXGBE_MPSAR_LO(rar)); } if (mpsar_hi) { IXGBE_WRITE_REG(hw, IXGBE_MPSAR_HI(rar), 0); - mpsar_hi = 0; + mpsar_hi = IXGBE_READ_REG(hw, IXGBE_MPSAR_HI(rar)); } } else if (vmdq < 32) { mpsar_lo &= ~(1 << vmdq); -- 2.20.1