Commit 60d75865 authored by Aleksandr Loktionov's avatar Aleksandr Loktionov Committed by David S. Miller
Browse files

igb: fix bit_shift to be in [1..8] range 



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: 9d5c8243 ("igb: PCI-Express 82575 Gigabit Ethernet driver")
Signed-off-by: default avatarAleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: default avatarTony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5ad3bd84

drivers/net/ethernet/intel/igb/e1000_mac.c

+2 −2
Original line number Diff line number Diff line
@@ -426,7 +426,7 @@ 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;
@@ -434,7 +434,7 @@ 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