src/patches/suse-2.6.27.25/patches.fixes/sn-irq-affinity

   1 From: Tony Ernst <tee@sgi.com>
   2 Subject: sn2: preserve irq affinity set in PROM
   3 Patch-mainline: No, this is a one-off from the mainline fix
   4 References: bnc#457679
   5
   6  The latest SLES11 has numerous changes in the
   7  request_irq() path, the one of issue is irq_select_affinity(),
   8  which reassigns an IRQ to a CPU. And, in the case of SN2 Altix,
   9  it assigns every IRQ to the same CPU; CPU0 in most cases, except
  10  on systems like rappel where it's CPU1, due to the Shub1.1 restrictions.
  11
  12  This is a problem. Unlike most platforms, on Altix, the assignment
  13  of an IRQ to a CPU is determined and setup in the PROM, and the kernel
  14  is not expected to change this, except in the case of a manual
  15  redirect/migration.
  16
  17 Acked-by: Jeff Mahoney <jeffm@suse.com>
  18 ---
  19  arch/ia64/sn/kernel/irq.c |    5 +++++
  20  include/linux/irq.h       |    1 +
  21  kernel/irq/manage.c       |   11 +++++++++++
  22  3 files changed, 17 insertions(+)
  23
  24 --- a/arch/ia64/sn/kernel/irq.c 2008-10-09 17:13:53.000000000 -0500
  25 +++ b/arch/ia64/sn/kernel/irq.c 2008-12-18 13:34:46.822283902 -0600
  26 @@ -391,6 +391,11 @@
  27  #ifdef CONFIG_SMP
  28         cpuphys = cpu_physical_id(cpu);
  29         set_irq_affinity_info(sn_irq_info->irq_irq, cpuphys, 0);
  30 +       /*
  31 +        * Affinity was set by the PROM, prevent it from
  32 +        * being reset by the request_irq() path.
  33 +        */
  34 +       irq_desc[sn_irq_info->irq_irq].status |= IRQ_AFFINITY_SET;
  35  #endif
  36  }
  37
  38 --- a/include/linux/irq.h       2008-12-16 11:27:10.000000000 -0600
  39 +++ b/include/linux/irq.h       2008-12-18 13:49:23.519706754 -0600
  40 @@ -63,6 +63,7 @@
  41  #define IRQ_NO_BALANCING       0x00400000      /* IRQ is excluded from balancing */
  42  #define IRQ_SPURIOUS_DISABLED  0x00800000      /* IRQ was disabled by the spurious trap */
  43  #define IRQ_MOVE_PCNTXT        0x01000000      /* IRQ migration from process context */
  44 +#define IRQ_AFFINITY_SET       0x02000000      /* IRQ affinity was previously set */
  45
  46  #ifdef CONFIG_IRQ_PER_CPU
  47  # define CHECK_IRQ_PER_CPU(var) ((var) & IRQ_PER_CPU)
  48 --- a/kernel/irq/manage.c       2008-12-16 11:27:10.000000000 -0600
  49 +++ b/kernel/irq/manage.c       2008-12-18 13:36:15.693395542 -0600
  50 @@ -117,6 +117,17 @@
  51
  52         cpus_and(mask, cpu_online_map, irq_default_affinity);
  53
  54 +       /*
  55 +        * Preserve the affinity that was previously set, but make
  56 +        * sure one of the targets is online.
  57 +        */
  58 +       if (irq_desc[irq].status & IRQ_AFFINITY_SET) {
  59 +               if (cpus_intersects(irq_desc[irq].affinity, cpu_online_map))
  60 +                       mask = irq_desc[irq].affinity;
  61 +               else
  62 +                       irq_desc[irq].status &= ~IRQ_AFFINITY_SET;
  63 +       }
  64 +
  65         irq_desc[irq].affinity = mask;
  66         irq_desc[irq].chip->set_affinity(irq, mask);
  67