Re: drivers/net/ethernet/intel/ice/ice_txrx.c:1304 ice_clean_rx_irq() error: uninitialized symbol 'cached_ntu'.

From: Alexander Lobakin
Date: Wed Mar 01 2023 - 07:07:33 EST

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In reply to: Dan Carpenter: "drivers/net/ethernet/intel/ice/ice_txrx.c:1304 ice_clean_rx_irq() error: uninitialized symbol 'cached_ntu'."
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From: Dan Carpenter <error27@xxxxxxxxx>
Date: Wed, 1 Mar 2023 08:00:07 +0300

Hi,

> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: c0927a7a5391f7d8e593e5e50ead7505a23cadf9
> commit: 3246a10752a7120878740f345f3956997777b3d6 ice: Add support for XDP multi-buffer on Tx side
> config: x86_64-randconfig-m001-20230227 (https://download.01.org/0day-ci/archive/20230301/202303011231.SEfXSwLT-lkp@xxxxxxxxx/config)
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> | Link: https://lore.kernel.org/r/202303011231.SEfXSwLT-lkp@xxxxxxxxx/
>
> New smatch warnings:
> drivers/net/ethernet/intel/ice/ice_txrx.c:1304 ice_clean_rx_irq() error: uninitialized symbol 'cached_ntu'.
>
> vim +/cached_ntu +1304 drivers/net/ethernet/intel/ice/ice_txrx.c
>
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1150
> eb087cd828648d Maciej Fijalkowski 2021-08-19 1151 xdp_prog = READ_ONCE(rx_ring->xdp_prog);
> 3246a10752a712 Maciej Fijalkowski 2023-01-31 1152 if (xdp_prog) {
> eb087cd828648d Maciej Fijalkowski 2021-08-19 1153 xdp_ring = rx_ring->xdp_ring;
> 3246a10752a712 Maciej Fijalkowski 2023-01-31 1154 cached_ntu = xdp_ring->next_to_use;
> 3246a10752a712 Maciej Fijalkowski 2023-01-31 1155 }
>
> Uninitialized on else path.
>
> eb087cd828648d Maciej Fijalkowski 2021-08-19 1156
> f9867df6d96593 Anirudh Venkataramanan 2019-02-19 1157 /* start the loop to process Rx packets bounded by 'budget' */
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1158 while (likely(total_rx_pkts < (unsigned int)budget)) {
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1159 union ice_32b_rx_flex_desc *rx_desc;
> 6c869cb7a8f02b Maciej Fijalkowski 2019-02-13 1160 struct ice_rx_buf *rx_buf;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1161 struct sk_buff *skb;
> 6c869cb7a8f02b Maciej Fijalkowski 2019-02-13 1162 unsigned int size;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1163 u16 stat_err_bits;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1164 u16 vlan_tag = 0;
> dda90cb90a5ced Jesse Brandeburg 2021-02-23 1165 u16 rx_ptype;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1166
> f9867df6d96593 Anirudh Venkataramanan 2019-02-19 1167 /* get the Rx desc from Rx ring based on 'next_to_clean' */
> d7956d81f1502d Maciej Fijalkowski 2023-01-31 1168 rx_desc = ICE_RX_DESC(rx_ring, ntc);
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1169
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1170 /* status_error_len will always be zero for unused descriptors
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1171 * because it's cleared in cleanup, and overlaps with hdr_addr
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1172 * which is always zero because packet split isn't used, if the
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1173 * hardware wrote DD then it will be non-zero
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1174 */
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1175 stat_err_bits = BIT(ICE_RX_FLEX_DESC_STATUS0_DD_S);
> 0d54d8f7a16de0 Brett Creeley 2021-12-02 1176 if (!ice_test_staterr(rx_desc->wb.status_error0, stat_err_bits))
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1177 break;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1178
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1179 /* This memory barrier is needed to keep us from reading
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1180 * any other fields out of the rx_desc until we know the
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1181 * DD bit is set.
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1182 */
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1183 dma_rmb();
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1184
> 3089cf6d3caa1e Jesse Brandeburg 2021-06-08 1185 ice_trace(clean_rx_irq, rx_ring, rx_desc);
> 148beb61203125 Henry Tieman 2020-05-11 1186 if (rx_desc->wb.rxdid == FDIR_DESC_RXDID || !rx_ring->netdev) {
> d6218317e2eff8 Qi Zhang 2021-03-09 1187 struct ice_vsi *ctrl_vsi = rx_ring->vsi;
> d6218317e2eff8 Qi Zhang 2021-03-09 1188
> d6218317e2eff8 Qi Zhang 2021-03-09 1189 if (rx_desc->wb.rxdid == FDIR_DESC_RXDID &&
> b03d519d3460f3 Jacob Keller 2022-02-16 1190 ctrl_vsi->vf)
> d6218317e2eff8 Qi Zhang 2021-03-09 1191 ice_vc_fdir_irq_handler(ctrl_vsi, rx_desc);
> d7956d81f1502d Maciej Fijalkowski 2023-01-31 1192 if (++ntc == cnt)
> d7956d81f1502d Maciej Fijalkowski 2023-01-31 1193 ntc = 0;
> 148beb61203125 Henry Tieman 2020-05-11 1194 continue;
> 148beb61203125 Henry Tieman 2020-05-11 1195 }
> 148beb61203125 Henry Tieman 2020-05-11 1196
> 6c869cb7a8f02b Maciej Fijalkowski 2019-02-13 1197 size = le16_to_cpu(rx_desc->wb.pkt_len) &
> 6c869cb7a8f02b Maciej Fijalkowski 2019-02-13 1198 ICE_RX_FLX_DESC_PKT_LEN_M;
> 6c869cb7a8f02b Maciej Fijalkowski 2019-02-13 1199
> ac6f733a7bd5e2 Mitch Williams 2019-07-25 1200 /* retrieve a buffer from the ring */
> d7956d81f1502d Maciej Fijalkowski 2023-01-31 1201 rx_buf = ice_get_rx_buf(rx_ring, size, ntc);
> ac6f733a7bd5e2 Mitch Williams 2019-07-25 1202
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1203 if (!xdp->data) {
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1204 void *hard_start;
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1205
> be9df4aff65f18 Lorenzo Bianconi 2020-12-22 1206 hard_start = page_address(rx_buf->page) + rx_buf->page_offset -
> be9df4aff65f18 Lorenzo Bianconi 2020-12-22 1207 offset;
> cb0473e0e9dcca Maciej Fijalkowski 2023-01-31 1208 xdp_prepare_buff(xdp, hard_start, offset, size, !!offset);
> d4ecdbf7aa2fa4 Jesper Dangaard Brouer 2020-05-14 1209 #if (PAGE_SIZE > 4096)
> d4ecdbf7aa2fa4 Jesper Dangaard Brouer 2020-05-14 1210 /* At larger PAGE_SIZE, frame_sz depend on len size */
> cb0473e0e9dcca Maciej Fijalkowski 2023-01-31 1211 xdp->frame_sz = ice_rx_frame_truesize(rx_ring, size);
> d4ecdbf7aa2fa4 Jesper Dangaard Brouer 2020-05-14 1212 #endif
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1213 xdp_buff_clear_frags_flag(xdp);
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1214 } else if (ice_add_xdp_frag(rx_ring, xdp, rx_buf, size)) {
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1215 break;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1216 }
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1217 if (++ntc == cnt)
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1218 ntc = 0;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1219
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1220 /* skip if it is NOP desc */
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1221 if (ice_is_non_eop(rx_ring, rx_desc))
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1222 continue;
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1223
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1224 ice_run_xdp(rx_ring, xdp, xdp_prog, xdp_ring, rx_buf);
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1225 if (rx_buf->act == ICE_XDP_PASS)
> 59bb0808055758 Maciej Fijalkowski 2019-10-24 1226 goto construct_skb;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1227 total_rx_bytes += xdp_get_buff_len(xdp);
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1228 total_rx_pkts++;
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1229
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1230 xdp->data = NULL;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1231 rx_ring->first_desc = ntc;
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1232 continue;
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1233 construct_skb:
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1234 if (likely(ice_ring_uses_build_skb(rx_ring)))
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1235 skb = ice_build_skb(rx_ring, xdp);
> 712edbbb67d404 Maciej Fijalkowski 2019-02-13 1236 else
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1237 skb = ice_construct_skb(rx_ring, xdp);
> 712edbbb67d404 Maciej Fijalkowski 2019-02-13 1238 /* exit if we failed to retrieve a buffer */
> 712edbbb67d404 Maciej Fijalkowski 2019-02-13 1239 if (!skb) {
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1240 rx_ring->ring_stats->rx_stats.alloc_page_failed++;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1241 rx_buf->act = ICE_XDP_CONSUMED;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1242 if (unlikely(xdp_buff_has_frags(xdp)))
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1243 ice_set_rx_bufs_act(xdp, rx_ring,
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1244 ICE_XDP_CONSUMED);
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1245 xdp->data = NULL;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1246 rx_ring->first_desc = ntc;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1247 break;
> 712edbbb67d404 Maciej Fijalkowski 2019-02-13 1248 }
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1249 xdp->data = NULL;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1250 rx_ring->first_desc = ntc;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1251
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1252 stat_err_bits = BIT(ICE_RX_FLEX_DESC_STATUS0_RXE_S);
> 0d54d8f7a16de0 Brett Creeley 2021-12-02 1253 if (unlikely(ice_test_staterr(rx_desc->wb.status_error0,
> 0d54d8f7a16de0 Brett Creeley 2021-12-02 1254 stat_err_bits))) {
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1255 dev_kfree_skb_any(skb);
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1256 continue;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1257 }
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1258
> 0d54d8f7a16de0 Brett Creeley 2021-12-02 1259 vlan_tag = ice_get_vlan_tag_from_rx_desc(rx_desc);
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1260
> 133f4883f90668 Krzysztof Kazimierczak 2019-10-09 1261 /* pad the skb if needed, to make a valid ethernet frame */
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1262 if (eth_skb_pad(skb))
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1263 continue;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1264
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1265 /* probably a little skewed due to removing CRC */
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1266 total_rx_bytes += skb->len;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1267
> d76a60ba7afb89 Anirudh Venkataramanan 2018-03-20 1268 /* populate checksum, VLAN, and protocol */
> 6503b659302893 Jesse Brandeburg 2019-08-08 1269 rx_ptype = le16_to_cpu(rx_desc->wb.ptype_flex_flags0) &
> 6503b659302893 Jesse Brandeburg 2019-08-08 1270 ICE_RX_FLEX_DESC_PTYPE_M;
> 6503b659302893 Jesse Brandeburg 2019-08-08 1271
> d76a60ba7afb89 Anirudh Venkataramanan 2018-03-20 1272 ice_process_skb_fields(rx_ring, rx_desc, skb, rx_ptype);
> d76a60ba7afb89 Anirudh Venkataramanan 2018-03-20 1273
> 3089cf6d3caa1e Jesse Brandeburg 2021-06-08 1274 ice_trace(clean_rx_irq_indicate, rx_ring, rx_desc, skb);
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1275 /* send completed skb up the stack */
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1276 ice_receive_skb(rx_ring, skb, vlan_tag);
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1277
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1278 /* update budget accounting */
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1279 total_rx_pkts++;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1280 }
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1281
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1282 first = rx_ring->first_desc;
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1283 while (cached_ntc != first) {
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1284 struct ice_rx_buf *buf = &rx_ring->rx_buf[cached_ntc];
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1285
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1286 if (buf->act & (ICE_XDP_TX | ICE_XDP_REDIR)) {
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1287 ice_rx_buf_adjust_pg_offset(buf, xdp->frame_sz);
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1288 xdp_xmit |= buf->act;
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1289 } else if (buf->act & ICE_XDP_CONSUMED) {
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1290 buf->pagecnt_bias++;
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1291 } else if (buf->act == ICE_XDP_PASS) {
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1292 ice_rx_buf_adjust_pg_offset(buf, xdp->frame_sz);
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1293 }
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1294
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1295 ice_put_rx_buf(rx_ring, buf);
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1296 if (++cached_ntc >= cnt)
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1297 cached_ntc = 0;
> 1dc1a7e7f4108b Maciej Fijalkowski 2023-01-31 1298 }
> d7956d81f1502d Maciej Fijalkowski 2023-01-31 1299 rx_ring->next_to_clean = ntc;
> cb7db35641c9a5 Brett Creeley 2019-06-26 1300 /* return up to cleaned_count buffers to hardware */
> 2fba7dc5157b6f Maciej Fijalkowski 2023-01-31 1301 failure = ice_alloc_rx_bufs(rx_ring, ICE_RX_DESC_UNUSED(rx_ring));
> cb7db35641c9a5 Brett Creeley 2019-06-26 1302
> 9070fe3da0b126 Maciej Fijalkowski 2023-01-31 1303 if (xdp_xmit)
> 3246a10752a712 Maciej Fijalkowski 2023-01-31 @1304 ice_finalize_xdp_rx(xdp_ring, xdp_xmit, cached_ntu);
> ^^^^^^^^^^

It's a false-positive, since @xdp_xmit can be non-zero only if @xdp_prog
is not %NULL. But we could always-initialize @cached_ntu to 0, will send
a fix soon.

>
>
> efc2214b6047b6 Maciej Fijalkowski 2019-11-04 1305
> 288ecf491b1654 Benjamin Mikailenko 2022-11-18 1306 if (rx_ring->ring_stats)
> 288ecf491b1654 Benjamin Mikailenko 2022-11-18 1307 ice_update_rx_ring_stats(rx_ring, total_rx_pkts,
> 288ecf491b1654 Benjamin Mikailenko 2022-11-18 1308 total_rx_bytes);
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1309
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1310 /* guarantee a trip back through this routine if there was a failure */
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1311 return failure ? budget : (int)total_rx_pkts;
> 2b245cb29421ab Anirudh Venkataramanan 2018-03-20 1312 }
>

Thanks,
Olek

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In reply to: Dan Carpenter: "drivers/net/ethernet/intel/ice/ice_txrx.c:1304 ice_clean_rx_irq() error: uninitialized symbol 'cached_ntu'."
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