Date:2010-08-09 13:27:14 (13 years 7 months ago)
Author:kaloz
Commit:6544569ed84b9bac668cb0e99436232aea49472d
Message:[cns3xxx]: workaround serial hang with SMP enabled

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@22557 3c298f89-4303-0410-b956-a3cf2f4a3e73
Files: target/linux/cns3xxx/patches-2.6.31/210-cns3xxx_smp_serial_fix.patch (1 diff)

Change Details

target/linux/cns3xxx/patches-2.6.31/210-cns3xxx_smp_serial_fix.patch
1--- a/drivers/serial/8250.c
2@@ -1743,6 +1743,7 @@ static void serial8250_backup_timeout(un
3     unsigned int iir, ier = 0, lsr;
4     unsigned long flags;
5
6+ spin_lock_irqsave(&up->port.lock, flags);
7     /*
8      * Must disable interrupts or else we risk racing with the interrupt
9      * based handler.
10@@ -1760,10 +1761,8 @@ static void serial8250_backup_timeout(un
11      * the "Diva" UART used on the management processor on many HP
12      * ia64 and parisc boxes.
13      */
14- spin_lock_irqsave(&up->port.lock, flags);
15     lsr = serial_in(up, UART_LSR);
16     up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
17- spin_unlock_irqrestore(&up->port.lock, flags);
18     if ((iir & UART_IIR_NO_INT) && (up->ier & UART_IER_THRI) &&
19         (!uart_circ_empty(&up->port.info->xmit) || up->port.x_char) &&
20         (lsr & UART_LSR_THRE)) {
21@@ -1771,12 +1770,14 @@ static void serial8250_backup_timeout(un
22         iir |= UART_IIR_THRI;
23     }
24
25- if (!(iir & UART_IIR_NO_INT))
26- serial8250_handle_port(up);
27-
28     if (is_real_interrupt(up->port.irq))
29         serial_out(up, UART_IER, ier);
30
31+ spin_unlock_irqrestore(&up->port.lock, flags);
32+
33+ if (!(iir & UART_IIR_NO_INT))
34+ serial8250_handle_port(up);
35+
36     /* Standard timer interval plus 0.2s to keep the port running */
37     mod_timer(&up->timer,
38         jiffies + poll_timeout(up->port.timeout) + HZ / 5);

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