Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'rework/atomic-flush-hardlockup' into for-linus
+44
-5
+44
-5
kernel/printk/nbcon.c
+44
-5
kernel/printk/nbcon.c
···
118
118
* from scratch.
119
119
*/
120
120
121
+
/* Counter of active nbcon emergency contexts. */
122
+
static atomic_t nbcon_cpu_emergency_cnt = ATOMIC_INIT(0);
123
+
121
124
/**
122
125
* nbcon_state_set - Helper function to set the console state
123
126
* @con: Console to update
···
1166
1163
if (kthread_should_stop())
1167
1164
return true;
1168
1165
1166
+
/*
1167
+
* Block the kthread when the system is in an emergency or panic mode.
1168
+
* It increases the chance that these contexts would be able to show
1169
+
* the messages directly. And it reduces the risk of interrupted writes
1170
+
* where the context with a higher priority takes over the nbcon console
1171
+
* ownership in the middle of a message.
1172
+
*/
1173
+
if (unlikely(atomic_read(&nbcon_cpu_emergency_cnt)) ||
1174
+
unlikely(panic_in_progress()))
1175
+
return false;
1176
+
1169
1177
cookie = console_srcu_read_lock();
1170
1178
1171
1179
flags = console_srcu_read_flags(con);
···
1227
1213
do {
1228
1214
if (kthread_should_stop())
1229
1215
return 0;
1216
+
1217
+
/*
1218
+
* Block the kthread when the system is in an emergency or panic
1219
+
* mode. See nbcon_kthread_should_wakeup() for more details.
1220
+
*/
1221
+
if (unlikely(atomic_read(&nbcon_cpu_emergency_cnt)) ||
1222
+
unlikely(panic_in_progress()))
1223
+
goto wait_for_event;
1230
1224
1231
1225
backlog = false;
1232
1226
···
1527
1505
ctxt->prio = nbcon_get_default_prio();
1528
1506
ctxt->allow_unsafe_takeover = allow_unsafe_takeover;
1529
1507
1530
-
if (!nbcon_context_try_acquire(ctxt, false))
1531
-
return -EPERM;
1532
-
1533
1508
while (nbcon_seq_read(con) < stop_seq) {
1509
+
if (!nbcon_context_try_acquire(ctxt, false))
1510
+
return -EPERM;
1511
+
1534
1512
/*
1535
1513
* nbcon_emit_next_record() returns false when the console was
1536
1514
* handed over or taken over. In both cases the context is no
···
1538
1516
*/
1539
1517
if (!nbcon_emit_next_record(&wctxt, true))
1540
1518
return -EAGAIN;
1519
+
1520
+
nbcon_context_release(ctxt);
1541
1521
1542
1522
if (!ctxt->backlog) {
1543
1523
/* Are there reserved but not yet finalized records? */
···
1549
1525
}
1550
1526
}
1551
1527
1552
-
nbcon_context_release(ctxt);
1553
1528
return err;
1554
1529
}
1555
1530
···
1678
1655
1679
1656
preempt_disable();
1680
1657
1658
+
atomic_inc(&nbcon_cpu_emergency_cnt);
1659
+
1681
1660
cpu_emergency_nesting = nbcon_get_cpu_emergency_nesting();
1682
1661
(*cpu_emergency_nesting)++;
1683
1662
}
···
1694
1669
unsigned int *cpu_emergency_nesting;
1695
1670
1696
1671
cpu_emergency_nesting = nbcon_get_cpu_emergency_nesting();
1697
-
1698
1672
if (!WARN_ON_ONCE(*cpu_emergency_nesting == 0))
1699
1673
(*cpu_emergency_nesting)--;
1674
+
1675
+
/*
1676
+
* Wake up kthreads because there might be some pending messages
1677
+
* added by other CPUs with normal priority since the last flush
1678
+
* in the emergency context.
1679
+
*/
1680
+
if (!WARN_ON_ONCE(atomic_read(&nbcon_cpu_emergency_cnt) == 0)) {
1681
+
if (atomic_dec_return(&nbcon_cpu_emergency_cnt) == 0) {
1682
+
struct console_flush_type ft;
1683
+
1684
+
printk_get_console_flush_type(&ft);
1685
+
if (ft.nbcon_offload)
1686
+
nbcon_kthreads_wake();
1687
+
}
1688
+
}
1700
1689
1701
1690
preempt_enable();
1702
1691
}