diff options
| author | Andrew Morton <akpm@osdl.org> | 2006-06-30 02:29:59 -0700 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2006-07-09 21:11:10 +0100 |
| commit | 68aa2c0d4a36b43ea9c6d77134c94b4501fd2eb4 (patch) | |
| tree | 92d401f58b6b4fdedb86ac973c74c2581b45de2c /drivers/serial/8250.c | |
| parent | 3be91ec7388bae3cf1bfb4febcee5ab6c65f409f (diff) | |
| download | lwn-68aa2c0d4a36b43ea9c6d77134c94b4501fd2eb4.tar.gz lwn-68aa2c0d4a36b43ea9c6d77134c94b4501fd2eb4.zip | |
[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/8250.c')
| -rw-r--r-- | drivers/serial/8250.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index 5443fcd38355..0ae9ced00ed4 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) |