Re: [PATCH v2] console: allocate ring buffer earlier

[Ian Campbell <Ian.Campbell@eu.citrix.com>]

On Tue, 2014-12-09 at 17:34 +0000, Jan Beulich wrote:
> ... when "conring_size=" was specified on the command line. We can't
> really do this as early as we would want to when the option was not
> specified, as the default depends on knowing the system CPU count. Yet
> the parsing of the ACPI tables is one of the things that generates a
> lot of output especially on large systems.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Ian Campbell <ian.campbell@citrix.com> (ARM  and generic bits)

> ---
> v2: Also adjust ARM (as requested by Julien). Rename new function to
>     console_init_ring().
> 
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -745,6 +745,7 @@ void __init start_xen(unsigned long boot
>  
>      dt_uart_init();
>      console_init_preirq();
> +    console_init_ring();
>  
>      system_state = SYS_STATE_boot;
>  
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1187,6 +1187,7 @@ void __init noreturn __start_xen(unsigne
>      }
>  
>      vm_init();
> +    console_init_ring();
>      vesa_init();
>  
>      softirq_init();
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -744,15 +744,14 @@ void __init console_init_preirq(void)
>      }
>  }
>  
> -void __init console_init_postirq(void)
> +void __init console_init_ring(void)
>  {
>      char *ring;
>      unsigned int i, order, memflags;
> -
> -    serial_init_postirq();
> +    unsigned long flags;
>  
>      if ( !opt_conring_size )
> -        opt_conring_size = num_present_cpus() << (9 + xenlog_lower_thresh);
> +        return;
>  
>      order = get_order_from_bytes(max(opt_conring_size, conring_size));
>      memflags = MEMF_bits(crashinfo_maxaddr_bits);
> @@ -763,17 +762,30 @@ void __init console_init_postirq(void)
>      }
>      opt_conring_size = PAGE_SIZE << order;
>  
> -    spin_lock_irq(&console_lock);
> +    spin_lock_irqsave(&console_lock, flags);
>      for ( i = conringc ; i != conringp; i++ )
>          ring[i & (opt_conring_size - 1)] = conring[i & (conring_size - 1)];
>      conring = ring;
>      smp_wmb(); /* Allow users of console_force_unlock() to see larger buffer. */
>      conring_size = opt_conring_size;
> -    spin_unlock_irq(&console_lock);
> +    spin_unlock_irqrestore(&console_lock, flags);
>  
>      printk("Allocated console ring of %u KiB.\n", opt_conring_size >> 10);
>  }
>  
> +void __init console_init_postirq(void)
> +{
> +    serial_init_postirq();
> +
> +    if ( conring != _conring )
> +        return;
> +
> +    if ( !opt_conring_size )
> +        opt_conring_size = num_present_cpus() << (9 + xenlog_lower_thresh);
> +
> +    console_init_ring();
> +}
> +
>  void __init console_endboot(void)
>  {
>      int i, j;
> --- a/xen/include/xen/console.h
> +++ b/xen/include/xen/console.h
> @@ -14,6 +14,7 @@ struct xen_sysctl_readconsole;
>  long read_console_ring(struct xen_sysctl_readconsole *op);
>  
>  void console_init_preirq(void);
> +void console_init_ring(void);
>  void console_init_postirq(void);
>  void console_endboot(void);
>  int console_has(const char *device);
> 
> 
>