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Message-ID: <202205100352.IRGYEdGU-lkp@intel.com>
Date: Tue, 10 May 2022 03:22:35 +0800
From: kernel test robot <lkp@...el.com>
To: David Howells <dhowells@...hat.com>
Cc: llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
GNU/Weeb Mailing List <gwml@...r.gnuweeb.org>,
linux-kernel@...r.kernel.org
Subject: [ammarfaizi2-block:dhowells/linux-fs/rxrpc-ringless 30/30]
net/rxrpc/call_event.c:157:6: warning: variable 'oldest' is used
uninitialized whenever 'if' condition is true
tree: https://github.com/ammarfaizi2/linux-block dhowells/linux-fs/rxrpc-ringless
head: 6c602b75eb616db42db08a634ed6e17ecd3a20d0
commit: 6c602b75eb616db42db08a634ed6e17ecd3a20d0 [30/30] rxrpc: Fix Tx resend by saving last ACK packet rather than marking packet ring
config: x86_64-randconfig-a004-20220509 (https://download.01.org/0day-ci/archive/20220510/202205100352.IRGYEdGU-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project a385645b470e2d3a1534aae618ea56b31177639f)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/ammarfaizi2/linux-block/commit/6c602b75eb616db42db08a634ed6e17ecd3a20d0
git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
git fetch --no-tags ammarfaizi2-block dhowells/linux-fs/rxrpc-ringless
git checkout 6c602b75eb616db42db08a634ed6e17ecd3a20d0
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash net/rxrpc/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>
All warnings (new ones prefixed by >>):
>> net/rxrpc/call_event.c:157:6: warning: variable 'oldest' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
if (list_empty(&call->tx_queue))
^~~~~~~~~~~~~~~~~~~~~~~~~~~
net/rxrpc/call_event.c:247:58: note: uninitialized use occurs here
resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
^~~~~~
include/linux/ktime.h:47:39: note: expanded from macro 'ktime_sub'
#define ktime_sub(lhs, rhs) ((lhs) - (rhs))
^~~
net/rxrpc/call_event.c:157:2: note: remove the 'if' if its condition is always false
if (list_empty(&call->tx_queue))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/rxrpc/call_event.c:134:30: note: initialize the variable 'oldest' to silence this warning
ktime_t now, max_age, oldest, ack_ts;
^
= 0
1 warning generated.
vim +157 net/rxrpc/call_event.c
122
123 /*
124 * Perform retransmission of NAK'd and unack'd packets.
125 */
126 static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
127 {
128 struct rxrpc_ackpacket *ack = NULL;
129 struct rxrpc_local *local = call->peer->local;
130 struct rxrpc_txbuf *txb;
131 struct sk_buff *ack_skb = NULL;
132 unsigned long resend_at;
133 rxrpc_seq_t transmitted = READ_ONCE(call->tx_transmitted);
134 ktime_t now, max_age, oldest, ack_ts;
135 bool unacked = false;
136 unsigned int i;
137 LIST_HEAD(retrans_queue);
138
139 _enter("{%d,%d}", call->acks_hard_ack, call->tx_top);
140
141 now = ktime_get_real();
142 max_age = ktime_sub_us(now, jiffies_to_usecs(call->peer->rto_j));
143
144 /* See if there's an ACK saved with a soft-ACK table in it. */
145 if (call->acks_soft_tbl) {
146 spin_lock_bh(&call->acks_ack_lock);
147 ack_skb = call->acks_soft_tbl;
148 if (ack_skb) {
149 rxrpc_get_skb(ack_skb, rxrpc_skb_ack);
150 ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);
151 }
152 spin_unlock_bh(&call->acks_ack_lock);
153 }
154
155 spin_lock(&call->tx_lock);
156
> 157 if (list_empty(&call->tx_queue))
158 goto no_resend;
159
160 trace_rxrpc_resend(call);
161 txb = list_first_entry(&call->tx_queue, struct rxrpc_txbuf, call_link);
162 oldest = now;
163
164 /* Scan the soft ACK table without dropping the lock and resend any
165 * explicitly NAK'd packets.
166 */
167 if (ack) {
168 for (i = 0; i < ack->nAcks; i++) {
169 rxrpc_seq_t seq;
170
171 if (ack->acks[i] & 1)
172 continue;
173 seq = ntohl(ack->firstPacket) + i;
174 if (after(txb->seq, transmitted))
175 break;
176 if (after(txb->seq, seq))
177 continue; /* A new hard ACK probably came in */
178 if (before(txb->seq, seq)) {
179 list_for_each_entry_continue(txb, &call->tx_queue, call_link) {
180 if (txb->seq == seq)
181 goto found_txb;
182 }
183 goto no_resend;
184 }
185
186 found_txb:
187 if (after(ntohl(txb->wire.serial), call->acks_highest_serial))
188 continue; /* Ack point not yet reached */
189
190 rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);
191
192 if (list_empty(&txb->tx_link)) {
193 rxrpc_get_txbuf(txb, rxrpc_txbuf_get_retrans);
194 rxrpc_get_call(call, rxrpc_call_got_tx);
195 list_add_tail(&txb->tx_link, &retrans_queue);
196 set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
197 }
198
199 trace_rxrpc_retransmit(call, txb->seq,
200 ktime_to_ns(ktime_sub(txb->last_sent,
201 max_age)));
202 }
203 }
204
205 /* Fast-forward through the Tx queue to the point the peer says it has
206 * seen. Anything between the soft-ACK table and that point will get
207 * ACK'd or NACK'd in due course, so don't worry about it here; here we
208 * need to consider retransmitting anything beyond that point.
209 *
210 * Note that ACK for a packet can beat the update of tx_transmitted.
211 */
212 if (after_eq(READ_ONCE(call->acks_prev_seq), READ_ONCE(call->tx_transmitted)))
213 goto no_resend;
214
215 list_for_each_entry_continue(txb, &call->tx_queue, call_link) {
216 if (before_eq(txb->seq, READ_ONCE(call->acks_prev_seq)))
217 continue;
218 if (after(txb->seq, READ_ONCE(call->tx_transmitted)))
219 break; /* Not transmitted yet */
220
221 if (ack && ack->reason == RXRPC_ACK_PING_RESPONSE &&
222 before(htonl(txb->wire.serial), htonl(ack->serial)))
223 goto do_resend; /* Wasn't accounted for by a more recent ping. */
224
225 if (ktime_after(txb->last_sent, max_age)) {
226 if (ktime_before(txb->last_sent, oldest))
227 oldest = txb->last_sent;
228 continue;
229 }
230
231 do_resend:
232 unacked = true;
233 if (list_empty(&txb->tx_link)) {
234 rxrpc_get_txbuf(txb, rxrpc_txbuf_get_retrans);
235 rxrpc_get_call(call, rxrpc_call_got_tx);
236 list_add_tail(&txb->tx_link, &retrans_queue);
237 set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
238 }
239 }
240
241
242
243 no_resend:
244 spin_unlock(&call->tx_lock);
245 rxrpc_free_skb(ack_skb, rxrpc_skb_freed);
246
247 resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
248 resend_at += jiffies + rxrpc_get_rto_backoff(call->peer,
249 !list_empty(&retrans_queue));
250 WRITE_ONCE(call->resend_at, resend_at);
251
252 if (unacked)
253 rxrpc_congestion_timeout(call);
254
255 /* If there was nothing that needed retransmission then it's likely
256 * that an ACK got lost somewhere. Send a ping to find out instead of
257 * retransmitting data.
258 */
259 if (list_empty(&retrans_queue)) {
260 rxrpc_reduce_call_timer(call, resend_at, now_j,
261 rxrpc_timer_set_for_resend);
262 ack_ts = ktime_sub(now, call->acks_latest_ts);
263 if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
264 goto out;
265 rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
266 rxrpc_propose_ack_ping_for_lost_ack);
267 goto out;
268 }
269
270 /* Push the packets to be retransmitted onto the transmission queue and
271 * wake up the transmitter worker. Note that it's possible that an ACK
272 * might come in whilst a packet is on the queue.
273 */
274 spin_lock(&local->tx_lock);
275 if (rxrpc_is_client_call(call))
276 rxrpc_expose_client_call(call);
277 list_splice_tail(&retrans_queue, &local->tx_queue);
278 spin_unlock(&local->tx_lock);
279 rxrpc_wake_up_transmitter(local);
280
281 out:
282 _leave("");
283 }
284
--
0-DAY CI Kernel Test Service
https://01.org/lkp
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