[paulmck-rcu:dev.2023.03.30a 28/35] kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
From: Dan Carpenter
Date: Tue Apr 04 2023 - 00:04:23 EST
tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.03.30a
head: e222f9a512539c3f4093a55d16624d9da614800b
commit: a63baab5f60110f3631c98b55d59066f1c68c4f7 [28/35] rcu: Employ jiffies-based backstop to callback time limit
config: openrisc-randconfig-m031-20230403 (https://download.01.org/0day-ci/archive/20230404/202304041113.A5sNFc2y-lkp@xxxxxxxxx/config)
compiler: or1k-linux-gcc (GCC) 12.1.0
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/202304041113.A5sNFc2y-lkp@xxxxxxxxx/
smatch warnings:
kernel/rcu/tree.c:2149 rcu_do_batch() error: uninitialized symbol 'jlimit'.
vim +/jlimit +2149 kernel/rcu/tree.c
5bb5d09cc4f868 kernel/rcu/tree.c Paul E. McKenney 2018-07-03 2065 static void rcu_do_batch(struct rcu_data *rdp)
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2066 {
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2067 long bl;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2068 long count = 0;
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2069 int div;
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2070) bool __maybe_unused empty;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2071 unsigned long flags;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2072 unsigned long jlimit;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2073 bool jlimit_check = false;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2074 long pending;
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2075 struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2076 struct rcu_head *rhp;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2077 long tlimit = 0;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2078
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2079 /* If no callbacks are ready, just return. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2080 if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2081 trace_rcu_batch_start(rcu_state.name,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2082 rcu_segcblist_n_cbs(&rdp->cblist), 0);
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2083 trace_rcu_batch_end(rcu_state.name, 0,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2084 !rcu_segcblist_empty(&rdp->cblist),
4968c300e1fa53 kernel/rcutree.c Paul E. McKenney 2011-12-07 2085 need_resched(), is_idle_task(current),
5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2086 rcu_is_callbacks_kthread(rdp));
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2087 return;
29c00b4a1d9e27 kernel/rcutree.c Paul E. McKenney 2011-06-17 2088 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2089
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2090 /*
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2091 * Extract the list of ready callbacks, disabling IRQs to prevent
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2092 * races with call_rcu() from interrupt handlers. Leave the
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2093 * callback counts, as rcu_barrier() needs to be conservative.
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2094 */
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2095 rcu_nocb_lock_irqsave(rdp, flags);
8146c4e2e2c197 kernel/rcutree.c Paul E. McKenney 2012-01-10 2096 WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
253cbbff621407 kernel/rcu/tree.c Paul E. McKenney 2022-11-14 2097 pending = rcu_segcblist_get_seglen(&rdp->cblist, RCU_DONE_TAIL);
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2098 div = READ_ONCE(rcu_divisor);
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2099 div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
b5374b2df0ac1c kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2100 bl = max(rdp->blimit, pending >> div);
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2101 if ((in_serving_softirq() || rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING) &&
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2102 (IS_ENABLED(CONFIG_RCU_DOUBLE_CHECK_CB_TIME) || unlikely(bl > 100))) {
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
jlimit is only initialized if one of these conditions is met.
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2103 const long npj = NSEC_PER_SEC / HZ;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2104 long rrn = READ_ONCE(rcu_resched_ns);
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2105
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2106 rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2107 tlimit = local_clock() + rrn;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2108 jlimit = jiffies + (rrn + npj + 1) / npj;
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2109 jlimit_check = true;
a2b354b9950bb8 kernel/rcu/tree.c Paul E. McKenney 2020-06-23 2110 }
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2111 trace_rcu_batch_start(rcu_state.name,
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2112 rcu_segcblist_n_cbs(&rdp->cblist), bl);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2113 rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
344e219d7d2b28 kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2114 if (rcu_rdp_is_offloaded(rdp))
7f36ef82e5cf0b kernel/rcu/tree.c Paul E. McKenney 2019-05-28 2115 rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2116)
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2117) trace_rcu_segcb_stats(&rdp->cblist, TPS("SegCbDequeued"));
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2118 rcu_nocb_unlock_irqrestore(rdp, flags);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2119
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2120 /* Invoke callbacks. */
6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2121 tick_dep_set_task(current, TICK_DEP_BIT_RCU);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2122 rhp = rcu_cblist_dequeue(&rcl);
3afe7fa535491e kernel/rcu/tree.c Joel Fernandes (Google 2020-11-14 2123)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2124 for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2125) rcu_callback_t f;
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2126)
6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2127) count++;
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2128 debug_rcu_head_unqueue(rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2129)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2130) rcu_lock_acquire(&rcu_callback_map);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2131) trace_rcu_invoke_callback(rcu_state.name, rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2132)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2133) f = rhp->func;
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2134) WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2135) f(rhp);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2136)
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2137) rcu_lock_release(&rcu_callback_map);
77a40f97030b27 kernel/rcu/tree.c Joel Fernandes (Google 2019-08-30 2138)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2139 /*
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2140 * Stop only if limit reached and CPU has something to do.
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2141 */
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2142 if (in_serving_softirq()) {
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2143 if (count >= bl && (need_resched() || !is_idle_task(current)))
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2144 break;
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2145 /*
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2146 * Make sure we don't spend too much time here and deprive other
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2147 * softirq vectors of CPU cycles.
3e61e95e2d095e kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2148 */
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 @2149 if (rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit))
^^^^^^
Uninitialized?
cfcdef5e30469f kernel/rcu/tree.c Eric Dumazet 2019-07-24 2150 break;
a554ba288845fd kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2151 } else {
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2152 // In rcuc/rcuoc context, so no worries about
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2153 // depriving other softirq vectors of CPU cycles.
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2154 local_bh_enable();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2155 lockdep_assert_irqs_enabled();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2156 cond_resched_tasks_rcu_qs();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2157 lockdep_assert_irqs_enabled();
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2158 local_bh_disable();
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2159 // But rcuc kthreads can delay quiescent-state
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2160 // reporting, so check time limits for them.
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2161 if (rdp->rcu_cpu_kthread_status == RCU_KTHREAD_RUNNING &&
a63baab5f60110 kernel/rcu/tree.c Paul E. McKenney 2023-03-31 2162 rcu_do_batch_check_time(count, tlimit, jlimit_check, jlimit)) {
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2163 rdp->rcu_cpu_has_work = 1;
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2164 break;
70c461b1465c5e kernel/rcu/tree.c Paul E. McKenney 2023-03-21 2165 }
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2166 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2167 }
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2168
7b65dfa32dca1b kernel/rcu/tree.c Frederic Weisbecker 2021-10-19 2169 rcu_nocb_lock_irqsave(rdp, flags);
e816d56fad57ba kernel/rcu/tree.c Paul E. McKenney 2020-05-01 2170 rdp->n_cbs_invoked += count;
3c779dfef2c452 kernel/rcu/tree.c Paul E. McKenney 2018-07-05 2171 trace_rcu_batch_end(rcu_state.name, count, !!rcl.head, need_resched(),
5103850654fdc6 kernel/rcu/tree.c Zqiang 2022-04-29 2172 is_idle_task(current), rcu_is_callbacks_kthread(rdp));
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2173
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2174 /* Update counts and requeue any remaining callbacks. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2175 rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl);
6bc335828056f3 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-03 2176) rcu_segcblist_add_len(&rdp->cblist, -count);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2177
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2178 /* Reinstate batch limit if we have worked down the excess. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2179 count = rcu_segcblist_n_cbs(&rdp->cblist);
d5a9a8c3bc8068 kernel/rcu/tree.c Paul E. McKenney 2019-04-10 2180 if (rdp->blimit >= DEFAULT_MAX_RCU_BLIMIT && count <= qlowmark)
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2181 rdp->blimit = blimit;
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2182
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2183 /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2184 if (count == 0 && rdp->qlen_last_fqs_check != 0) {
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2185 rdp->qlen_last_fqs_check = 0;
2431774f04d105 kernel/rcu/tree.c Paul E. McKenney 2021-07-20 2186 rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2187 } else if (count < rdp->qlen_last_fqs_check - qhimark)
15fecf89e46a96 kernel/rcu/tree.c Paul E. McKenney 2017-02-08 2188 rdp->qlen_last_fqs_check = count;
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2189
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2190 /*
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2191 * The following usually indicates a double call_rcu(). To track
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2192 * this down, try building with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.
efd88b02bb9e6b kernel/rcu/tree.c Paul E. McKenney 2017-10-19 2193 */
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2194) empty = rcu_segcblist_empty(&rdp->cblist);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2195) WARN_ON_ONCE(count == 0 && !empty);
d1b222c6be1f8b kernel/rcu/tree.c Paul E. McKenney 2019-07-02 2196 WARN_ON_ONCE(!IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2197) count != 0 && empty);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2198) WARN_ON_ONCE(count == 0 && rcu_segcblist_n_segment_cbs(&rdp->cblist) != 0);
b4e6039e8af8c2 kernel/rcu/tree.c Joel Fernandes (Google 2020-11-18 2199) WARN_ON_ONCE(!empty && rcu_segcblist_n_segment_cbs(&rdp->cblist) == 0);
37c72e56f6b234 kernel/rcutree.c Paul E. McKenney 2009-10-14 2200
5d6742b37727e1 kernel/rcu/tree.c Paul E. McKenney 2019-05-15 2201 rcu_nocb_unlock_irqrestore(rdp, flags);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2202
6a949b7af82db7 kernel/rcu/tree.c Paul E. McKenney 2019-07-28 2203 tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
64db4cfff99c04 kernel/rcutree.c Paul E. McKenney 2008-12-18 2204 }
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