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authorIngo Molnar <mingo@elte.hu>2014-03-07 17:58:39 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-03-09 10:24:53 +0400
commitebade5e833eda30f648d9bf4954f7d47a920b60f (patch)
tree9c767fdb3861ccfdde38564edff76adeef1c1882 /drivers/tty
parent41d3f09913a930369a26616eedc02339d0455498 (diff)
downloadlinux-ebade5e833eda30f648d9bf4954f7d47a920b60f.tar.xz
serial: 8250: Clean up the locking for -rt
In -RT the spin_lock_irqsave() does not spin but sleep if the lock is taken. Before that, local_irq_save() is invoked which disables interrupts even on -RT. Therefore local_irq_save() + spin_lock() does not work. In the ->sysrq and oops_in_progress case it is save to trylock the lock i.e. this is what we do now anyway except for ->sysrq where we assume that the lock is already taken. The spin_lock_irqsave() grabs the lock and disables the interrupts on vanilla (the same behavior) and on -RT it won't disable interrupts. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bigeasy: add a patch description] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/8250/8250_core.c15
1 files changed, 5 insertions, 10 deletions
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 747073b8c38a..81f909c2101f 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -2886,14 +2886,10 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
touch_nmi_watchdog();
- local_irq_save(flags);
- if (port->sysrq) {
- /* serial8250_handle_irq() already took the lock */
- locked = 0;
- } else if (oops_in_progress) {
- locked = spin_trylock(&port->lock);
- } else
- spin_lock(&port->lock);
+ if (port->sysrq || oops_in_progress)
+ locked = spin_trylock_irqsave(&port->lock, flags);
+ else
+ spin_lock_irqsave(&port->lock, flags);
/*
* First save the IER then disable the interrupts
@@ -2925,8 +2921,7 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
serial8250_modem_status(up);
if (locked)
- spin_unlock(&port->lock);
- local_irq_restore(flags);
+ spin_unlock_irqrestore(&port->lock, flags);
}
static int __init serial8250_console_setup(struct console *co, char *options)