This is a note to let you know that I've just added the patch titled
igb: fix bit_shift to be in [1..8] range
to the 4.19-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:
igb-fix-bit_shift-to-be-in-1.8-range.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a87a6184863004c06df64da4f6b5cee006680ec1
Author: Aleksandr Loktionov <aleksandr.loktionov@xxxxxxxxx>
Date: Tue May 16 10:41:46 2023 -0700
igb: fix bit_shift to be in [1..8] range
[ Upstream commit 60d758659f1fb49e0d5b6ac2691ede8c0958795b ]
In igb_hash_mc_addr() the expression:
"mc_addr[4] >> 8 - bit_shift", right shifting "mc_addr[4]"
shift by more than 7 bits always yields zero, so hash becomes not so different.
Add initialization with bit_shift = 1 and add a loop condition to ensure
bit_shift will be always in [1..8] range.
Fixes: 9d5c824399de ("igb: PCI-Express 82575 Gigabit Ethernet driver")
Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@xxxxxxxxx>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@xxxxxxxxx> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/intel/igb/e1000_mac.c b/drivers/net/ethernet/intel/igb/e1000_mac.c
index 79ee0a7472608..4e69cb2c025fd 100644
--- a/drivers/net/ethernet/intel/igb/e1000_mac.c
+++ b/drivers/net/ethernet/intel/igb/e1000_mac.c
@@ -425,7 +425,7 @@ void igb_mta_set(struct e1000_hw *hw, u32 hash_value)
static u32 igb_hash_mc_addr(struct e1000_hw *hw, u8 *mc_addr)
{
u32 hash_value, hash_mask;
- u8 bit_shift = 0;
+ u8 bit_shift = 1;
/* Register count multiplied by bits per register */
hash_mask = (hw->mac.mta_reg_count * 32) - 1;
@@ -433,7 +433,7 @@ static u32 igb_hash_mc_addr(struct e1000_hw *hw, u8 *mc_addr)
/* For a mc_filter_type of 0, bit_shift is the number of left-shifts
* where 0xFF would still fall within the hash mask.
*/
- while (hash_mask >> bit_shift != 0xFF)
+ while (hash_mask >> bit_shift != 0xFF && bit_shift < 4)
bit_shift++;
/* The portion of the address that is used for the hash table
