Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'printk-for-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk fix from Petr Mladek:
- Prevent softlockup by restoring IRQs in atomic flush after each
record
* tag 'printk-for-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk/nbcon: Restore IRQ in atomic flush after each emitted record
+18
-20
+18
-20
kernel/printk/nbcon.c
+18
-20
kernel/printk/nbcon.c
···
1557
1557
ctxt->allow_unsafe_takeover = nbcon_allow_unsafe_takeover();
1558
1558
1559
1559
while (nbcon_seq_read(con) < stop_seq) {
1560
-
if (!nbcon_context_try_acquire(ctxt, false))
1561
-
return -EPERM;
1562
-
1563
1560
/*
1564
-
* nbcon_emit_next_record() returns false when the console was
1565
-
* handed over or taken over. In both cases the context is no
1566
-
* longer valid.
1561
+
* Atomic flushing does not use console driver synchronization
1562
+
* (i.e. it does not hold the port lock for uart consoles).
1563
+
* Therefore IRQs must be disabled to avoid being interrupted
1564
+
* and then calling into a driver that will deadlock trying
1565
+
* to acquire console ownership.
1567
1566
*/
1568
-
if (!nbcon_emit_next_record(&wctxt, true))
1569
-
return -EAGAIN;
1567
+
scoped_guard(irqsave) {
1568
+
if (!nbcon_context_try_acquire(ctxt, false))
1569
+
return -EPERM;
1570
1570
1571
-
nbcon_context_release(ctxt);
1571
+
/*
1572
+
* nbcon_emit_next_record() returns false when
1573
+
* the console was handed over or taken over.
1574
+
* In both cases the context is no longer valid.
1575
+
*/
1576
+
if (!nbcon_emit_next_record(&wctxt, true))
1577
+
return -EAGAIN;
1578
+
1579
+
nbcon_context_release(ctxt);
1580
+
}
1572
1581
1573
1582
if (!ctxt->backlog) {
1574
1583
/* Are there reserved but not yet finalized records? */
···
1604
1595
static void nbcon_atomic_flush_pending_con(struct console *con, u64 stop_seq)
1605
1596
{
1606
1597
struct console_flush_type ft;
1607
-
unsigned long flags;
1608
1598
int err;
1609
1599
1610
1600
again:
1611
-
/*
1612
-
* Atomic flushing does not use console driver synchronization (i.e.
1613
-
* it does not hold the port lock for uart consoles). Therefore IRQs
1614
-
* must be disabled to avoid being interrupted and then calling into
1615
-
* a driver that will deadlock trying to acquire console ownership.
1616
-
*/
1617
-
local_irq_save(flags);
1618
-
1619
1601
err = __nbcon_atomic_flush_pending_con(con, stop_seq);
1620
-
1621
-
local_irq_restore(flags);
1622
1602
1623
1603
/*
1624
1604
* If there was a new owner (-EPERM, -EAGAIN), that context is