diff options
Diffstat (limited to 'features/rt/tty-serial-pl011-Make-the-locking-work-on-RT.patch')
| -rw-r--r-- | features/rt/tty-serial-pl011-Make-the-locking-work-on-RT.patch | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/features/rt/tty-serial-pl011-Make-the-locking-work-on-RT.patch b/features/rt/tty-serial-pl011-Make-the-locking-work-on-RT.patch new file mode 100644 index 00000000..8d9cbe4a --- /dev/null +++ b/features/rt/tty-serial-pl011-Make-the-locking-work-on-RT.patch @@ -0,0 +1,59 @@ +From c93bc4171de555594d642d4f673d68377fbcc274 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Tue, 8 Jan 2013 21:36:51 +0100 +Subject: [PATCH 172/191] tty/serial/pl011: Make the locking work on RT + +The lock is a sleeping lock and local_irq_save() is not the optimsation +we are looking for. Redo it to make it work on -RT and non-RT. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + drivers/tty/serial/amba-pl011.c | 17 +++++++++++------ + 1 file changed, 11 insertions(+), 6 deletions(-) + +diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c +index 4ead0c9048a8..1bbc56263c2d 100644 +--- a/drivers/tty/serial/amba-pl011.c ++++ b/drivers/tty/serial/amba-pl011.c +@@ -2201,18 +2201,24 @@ pl011_console_write(struct console *co, const char *s, unsigned int count) + { + struct uart_amba_port *uap = amba_ports[co->index]; + unsigned int old_cr = 0, new_cr; +- unsigned long flags; ++ unsigned long flags = 0; + int locked = 1; + + clk_enable(uap->clk); + +- local_irq_save(flags); ++ /* ++ * local_irq_save(flags); ++ * ++ * This local_irq_save() is nonsense. If we come in via sysrq ++ * handling then interrupts are already disabled. Aside of ++ * that the port.sysrq check is racy on SMP regardless. ++ */ + if (uap->port.sysrq) + locked = 0; + else if (oops_in_progress) +- locked = spin_trylock(&uap->port.lock); ++ locked = spin_trylock_irqsave(&uap->port.lock, flags); + else +- spin_lock(&uap->port.lock); ++ spin_lock_irqsave(&uap->port.lock, flags); + + /* + * First save the CR then disable the interrupts +@@ -2238,8 +2244,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count) + pl011_write(old_cr, uap, REG_CR); + + if (locked) +- spin_unlock(&uap->port.lock); +- local_irq_restore(flags); ++ spin_unlock_irqrestore(&uap->port.lock, flags); + + clk_disable(uap->clk); + } +-- +2.19.1 + |