[PATCH 5.15 029/124] igc: Fix infinite loop in release_swfw_sync

Greg Kroah-Hartman
2022-04-26T08:58:38Z

From: Sasha Neftin <sasha.neftin@intel.com>

[ Upstream commit 907862e9aef75bf89e2b265efcc58870be06081e ]

An infinite loop may occur if we fail to acquire the HW semaphore,
which is needed for resource release.
This will typically happen if the hardware is surprise-removed.
At this stage there is nothing to do, except log an error and quit.

Fixes: c0071c7aa5fe ("igc: Add HW initialization code")
Suggested-by: Dima Ruinskiy <dima.ruinskiy@intel.com>
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/igc/igc_i225.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_i225.c b/drivers/net/ethernet/intel/igc/igc_i225.c
index b6807e16eea9..a0e2a404d535 100644
--- a/drivers/net/ethernet/intel/igc/igc_i225.c
+++ b/drivers/net/ethernet/intel/igc/igc_i225.c
@@ -156,8 +156,15 @@ void igc_release_swfw_sync_i225(struct igc_hw *hw, u16 mask)
{
u32 swfw_sync;

- while (igc_get_hw_semaphore_i225(hw))
- ; /* Empty */
+ /* Releasing the resource requires first getting the HW semaphore.
+ * If we fail to get the semaphore, there is nothing we can do,
+ * except log an error and quit. We are not allowed to hang here
+ * indefinitely, as it may cause denial of service or system crash.
+ */
+ if (igc_get_hw_semaphore_i225(hw)) {
+ hw_dbg("Failed to release SW_FW_SYNC.\n");
+ return;
+ }

swfw_sync = rd32(IGC_SW_FW_SYNC);
swfw_sync &= ~mask;
--
2.35.1