Merge branch 'introduce-define_flex-macro'

Przemek Kitszel says:

====================
introduce DEFINE_FLEX() macro

Add DEFINE_FLEX() macro, that helps on-stack allocation of structures
with trailing flex array member.
Expose __struct_size() macro which reads size of data allocated
by DEFINE_FLEX().

Accompany new macros introduction with actual usage,
in the ice driver - hence targeting for netdev tree.

Obvious benefits include simpler resulting code, less heap usage,
less error checking. Less obvious is the fact that compiler has
more room to optimize, and as a whole, even with more stuff on the stack,
we end up with overall better (smaller) report from bloat-o-meter:
add/remove: 8/6 grow/shrink: 7/18 up/down: 2211/-2270 (-59)
(individual results in each patch).
====================

Link: https://lore.kernel.org/r/20230912115937.1645707-1-przemyslaw.kitszel@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 5 insertions, 18 deletions

diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
index 1549890a3cbf..aed84d369daf 100644
--- a/drivers/net/ethernet/intel/ice/ice_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_lib.c
@@ -1832,21 +1832,14 @@ int ice_vsi_cfg_single_rxq(struct ice_vsi *vsi, u16 q_idx)
 
 int ice_vsi_cfg_single_txq(struct ice_vsi *vsi, struct ice_tx_ring **tx_rings, u16 q_idx)
 {
-	struct ice_aqc_add_tx_qgrp *qg_buf;
-	int err;
+	DEFINE_FLEX(struct ice_aqc_add_tx_qgrp, qg_buf, txqs, 1);
 
 	if (q_idx >= vsi->alloc_txq || !tx_rings || !tx_rings[q_idx])
 		return -EINVAL;
 
-	qg_buf = kzalloc(struct_size(qg_buf, txqs, 1), GFP_KERNEL);
-	if (!qg_buf)
-		return -ENOMEM;
-
 	qg_buf->num_txqs = 1;
 
-	err = ice_vsi_cfg_txq(vsi, tx_rings[q_idx], qg_buf);
-	kfree(qg_buf);
-	return err;
+	return ice_vsi_cfg_txq(vsi, tx_rings[q_idx], qg_buf);
 }
 
 /**
@@ -1888,24 +1881,18 @@ setup_rings:
 static int
 ice_vsi_cfg_txqs(struct ice_vsi *vsi, struct ice_tx_ring **rings, u16 count)
 {
-	struct ice_aqc_add_tx_qgrp *qg_buf;
-	u16 q_idx = 0;
+	DEFINE_FLEX(struct ice_aqc_add_tx_qgrp, qg_buf, txqs, 1);
 	int err = 0;
-
-	qg_buf = kzalloc(struct_size(qg_buf, txqs, 1), GFP_KERNEL);
-	if (!qg_buf)
-		return -ENOMEM;
+	u16 q_idx;
 
 	qg_buf->num_txqs = 1;
 
 	for (q_idx = 0; q_idx < count; q_idx++) {
 		err = ice_vsi_cfg_txq(vsi, rings[q_idx], qg_buf);
 		if (err)
-			goto err_cfg_txqs;
+			break;
 	}
 
-err_cfg_txqs:
-	kfree(qg_buf);
 	return err;
 }