Patch "igc: fix the validation logic for taprio's gate list" 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

    igc: fix the validation logic for taprio's gate list

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:
     igc-fix-the-validation-logic-for-taprio-s-gate-list.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 66b6f59c46b19faef8b94897fa48ae1a3ba0a218
Author: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
Date:   Tue Mar 7 15:45:31 2023 +0900

    igc: fix the validation logic for taprio's gate list
    
    [ Upstream commit 2b4cc3d3f4d8ec42961e98568a0afeee96a943ab ]
    
    The check introduced in the commit a5fd39464a40 ("igc: Lift TAPRIO schedule
    restriction") can detect a false positive error in some corner case.
    For instance,
        tc qdisc replace ... taprio num_tc 4
            ...
            sched-entry S 0x01 100000       # slot#1
            sched-entry S 0x03 100000       # slot#2
            sched-entry S 0x04 100000       # slot#3
            sched-entry S 0x08 200000       # slot#4
            flags 0x02                      # hardware offload
    
    Here the queue#0 (the first queue) is on at the slot#1 and #2,
    and off at the slot#3 and #4. Under the current logic, when the slot#4
    is examined, validate_schedule() returns *false* since the enablement
    count for the queue#0 is two and it is already off at the previous slot
    (i.e. #3). But this definition is truely correct.
    
    Let's fix the logic to enforce a strict validation for consecutively-opened
    slots.
    
    Fixes: a5fd39464a40 ("igc: Lift TAPRIO schedule restriction")
    Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
    Reviewed-by: Kurt Kanzenbach <kurt@xxxxxxxxxxxxx>
    Acked-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
    Tested-by: Naama Meir <naamax.meir@xxxxxxxxxxxxxxx>
    Signed-off-by: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index bde3fea2c442e..e255b0a004f88 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5951,18 +5951,18 @@ static bool validate_schedule(struct igc_adapter *adapter,
 		if (e->command != TC_TAPRIO_CMD_SET_GATES)
 			return false;
 
-		for (i = 0; i < adapter->num_tx_queues; i++) {
-			if (e->gate_mask & BIT(i))
+		for (i = 0; i < adapter->num_tx_queues; i++)
+			if (e->gate_mask & BIT(i)) {
 				queue_uses[i]++;
 
-			/* There are limitations: A single queue cannot be
-			 * opened and closed multiple times per cycle unless the
-			 * gate stays open. Check for it.
-			 */
-			if (queue_uses[i] > 1 &&
-			    !(prev->gate_mask & BIT(i)))
-				return false;
-		}
+				/* There are limitations: A single queue cannot
+				 * be opened and closed multiple times per cycle
+				 * unless the gate stays open. Check for it.
+				 */
+				if (queue_uses[i] > 1 &&
+				    !(prev->gate_mask & BIT(i)))
+					return false;
+			}
 	}
 
 	return true;