Hi, David!
On 04.03.2014 23:10, David Miller wrote:
> From: Kirill Tkhai <tkhai@xxxxxxxxx>
> Date: Fri, 28 Feb 2014 18:51:23 +0400
>
>> This should be fixed like that's done for 8250
>> [patch drivers-serial-cleanup-locking-for-rt.patch]
>
> Like the patch below?
Exactly this.
> Is this transformation legitimate outside of the -rt tree? I wish the commit
> messages for the 8250 change was more verbose, explaining exactly why this
> is needed.
>
> And if it's needed, all the sparc serial/console drivers need this too.
port->lock is mutex, so we should not disable interrupts before we are
doing spin_lock(). In RT spin_trylock_irqsave() does not disable irqs.
The patch is made to be good for both RT and !RT cases, so everything
is ok!
Really I don't know, why the original patch is not in upstream
***shrugging***. It's from 2009, everything is possible.
> diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
> index cf86e72..dc697ce 100644
> --- a/drivers/tty/serial/sunhv.c
> +++ b/drivers/tty/serial/sunhv.c
> @@ -433,13 +433,10 @@ static void sunhv_console_write_paged(struct console *con, const char *s, unsign
> unsigned long flags;
> int locked = 1;
>
> - local_irq_save(flags);
> - if (port->sysrq) {
> - 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);
>
> while (n > 0) {
> unsigned long ra = __pa(con_write_page);
> @@ -470,8 +467,7 @@ static void sunhv_console_write_paged(struct console *con, const char *s, unsign
> }
>
> if (locked)
> - spin_unlock(&port->lock);
> - local_irq_restore(flags);
> + spin_unlock_irqrestore(&port->lock, flags);
> }
>
> static inline void sunhv_console_putchar(struct uart_port *port, char c)
> @@ -492,7 +488,10 @@ static void sunhv_console_write_bychar(struct console *con, const char *s, unsig
> unsigned long flags;
> int i, locked = 1;
>
> - local_irq_save(flags);
> + if (port->sysrq || oops_in_progress)
> + locked = spin_trylock_irqsave(&port->lock, flags);
> + else
> + spin_lock_irqsave(&port->lock, flags);
> if (port->sysrq) {
> locked = 0;
> } else if (oops_in_progress) {
> @@ -507,8 +506,7 @@ static void sunhv_console_write_bychar(struct console *con, const char *s, unsig
> }
>
> if (locked)
> - spin_unlock(&port->lock);
> - local_irq_restore(flags);
> + spin_unlock_irqrestore(&port->lock, flags);
> }
>
> static struct console sunhv_console = {
>
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