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authorAndrew Morton <akpm@osdl.org>2006-06-30 02:29:59 -0700
committerRussell King <rmk+kernel@arm.linux.org.uk>2006-07-09 21:11:10 +0100
commit68aa2c0d4a36b43ea9c6d77134c94b4501fd2eb4 (patch)
tree92d401f58b6b4fdedb86ac973c74c2581b45de2c /drivers/serial
parent3be91ec7388bae3cf1bfb4febcee5ab6c65f409f (diff)
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[SERIAL] 8250: sysrq deadlock fix
Fix http://bugzilla.kernel.org/show_bug.cgi?id=6716 Doing a sysrq over a serial line into an SMP machine presently deadlocks. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'drivers/serial')
-rw-r--r--drivers/serial/8250.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 5443fcd..0ae9ced 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2252,10 +2252,14 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
touch_nmi_watchdog();
- if (oops_in_progress) {
- locked = spin_trylock_irqsave(&up->port.lock, flags);
+ local_irq_save(flags);
+ if (up->port.sysrq) {
+ /* serial8250_handle_port() already took the lock */
+ locked = 0;
+ } else if (oops_in_progress) {
+ locked = spin_trylock(&up->port.lock);
} else
- spin_lock_irqsave(&up->port.lock, flags);
+ spin_lock(&up->port.lock);
/*
* First save the IER then disable the interrupts
@@ -2277,7 +2281,8 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
serial_out(up, UART_IER, ier);
if (locked)
- spin_unlock_irqrestore(&up->port.lock, flags);
+ spin_unlock(&up->port.lock);
+ local_irq_restore(flags);
}
static int serial8250_console_setup(struct console *co, char *options)