ice: reduce size of queue context fields

The ice_rlan_ctx and ice_tlan_ctx structures have some fields which are
intentionally sized larger than necessary relative to the packed sizes the
data must fit into. This was done because the original ice_set_ctx()
function and its helpers did not correctly handle packing when the packed
bits straddled a byte. This is no longer the case with the use of the
<linux/packing.h> implementation.

Save some bytes in these structures by sizing the variables to the number
of bytes the actual bitpacked fields fit into.

There are a couple of gaps left in the structure, which is a result of the
fields being in the order they appear in the packed bit layout, but where
alignment forces some extra gaps. We could fix this, saving ~8 bytes from
each structure. However, these structures are not used heavily, and the
resulting savings is minimal:

$ bloat-o-meter ice-before-reorder.ko ice-after-reorder.ko
add/remove: 0/0 grow/shrink: 1/1 up/down: 26/-70 (-44)
Function                                     old     new   delta
ice_vsi_cfg_txq                             1873    1899     +26
ice_setup_rx_ctx.constprop                  1529    1459     -70
Total: Before=1459555, After=1459511, chg -0.00%

Thus, the fields are left in the same order as the packed bit layout,
despite the gaps this causes.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241210-packing-pack-fields-and-ice-implementation-v10-8-ee56a47479ac@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/intel/ice/ice_lan_tx_rx.h b/drivers/net/ethernet/intel/ice/ice_lan_tx_rx.h
index 31d4a445d640df21c2aa007ffbd4f2310da264ad..1479b45738af15bf6e00aed24b2c6a3f91675f4d 100644 (file)
--- a/drivers/net/ethernet/intel/ice/ice_lan_tx_rx.h
+++ b/drivers/net/ethernet/intel/ice/ice_lan_tx_rx.h
@@ -375,23 +375,17 @@ enum ice_rx_flex_desc_status_error_1_bits {
 #define ICE_TX_DRBELL_Q_CTX_SIZE_DWORDS        5
 #define GLTCLAN_CQ_CNTX(i, CQ)         (GLTCLAN_CQ_CNTX0(CQ) + ((i) * 0x0800))
 
-/* RLAN Rx queue context data
- *
- * The sizes of the variables may be larger than needed due to crossing byte
- * boundaries. If we do not have the width of the variable set to the correct
- * size then we could end up shifting bits off the top of the variable when the
- * variable is at the top of a byte and crosses over into the next byte.
- */
+/* RLAN Rx queue context data */
 struct ice_rlan_ctx {
        u16 head;
-       u16 cpuid; /* bigger than needed, see above for reason */
+       u8 cpuid;
 #define ICE_RLAN_BASE_S 7
        u64 base;
        u16 qlen;
 #define ICE_RLAN_CTX_DBUF_S 7
-       u16 dbuf; /* bigger than needed, see above for reason */
+       u8 dbuf;
 #define ICE_RLAN_CTX_HBUF_S 6
-       u16 hbuf; /* bigger than needed, see above for reason */
+       u8 hbuf;
        u8 dtype;
        u8 dsize;
        u8 crcstrip;
@@ -399,12 +393,12 @@ struct ice_rlan_ctx {
        u8 hsplit_0;
        u8 hsplit_1;
        u8 showiv;
-       u32 rxmax; /* bigger than needed, see above for reason */
+       u16 rxmax;
        u8 tphrdesc_ena;
        u8 tphwdesc_ena;
        u8 tphdata_ena;
        u8 tphhead_ena;
-       u16 lrxqthresh; /* bigger than needed, see above for reason */
+       u8 lrxqthresh;
        u8 prefena;     /* NOTE: normally must be set to 1 at init */
 };
 
@@ -535,18 +529,12 @@ enum ice_tx_ctx_desc_eipt_offload {
 #define ICE_LAN_TXQ_MAX_QGRPS  127
 #define ICE_LAN_TXQ_MAX_QDIS   1023
 
-/* Tx queue context data
- *
- * The sizes of the variables may be larger than needed due to crossing byte
- * boundaries. If we do not have the width of the variable set to the correct
- * size then we could end up shifting bits off the top of the variable when the
- * variable is at the top of a byte and crosses over into the next byte.
- */
+/* Tx queue context data */
 struct ice_tlan_ctx {
 #define ICE_TLAN_CTX_BASE_S    7
        u64 base;               /* base is defined in 128-byte units */
        u8 port_num;
-       u16 cgd_num;            /* bigger than needed, see above for reason */
+       u8 cgd_num;
        u8 pf_num;
        u16 vmvf_num;
        u8 vmvf_type;
@@ -557,7 +545,7 @@ struct ice_tlan_ctx {
        u8 tsyn_ena;
        u8 internal_usage_flag;
        u8 alt_vlan;
-       u16 cpuid;              /* bigger than needed, see above for reason */
+       u8 cpuid;
        u8 wb_mode;
        u8 tphrd_desc;
        u8 tphrd;
@@ -566,7 +554,7 @@ struct ice_tlan_ctx {
        u16 qnum_in_func;
        u8 itr_notification_mode;
        u8 adjust_prof_id;
-       u32 qlen;               /* bigger than needed, see above for reason */
+       u16 qlen;
        u8 quanta_prof_idx;
        u8 tso_ena;
        u16 tso_qnum;