diff options
Diffstat (limited to 'arch/ia64/sn/kernel/sn2/sn2_smp.c')
| -rw-r--r-- | arch/ia64/sn/kernel/sn2/sn2_smp.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c index 471bbaa65d1b..1b33fd5e4e3a 100644 --- a/arch/ia64/sn/kernel/sn2/sn2_smp.c +++ b/arch/ia64/sn/kernel/sn2/sn2_smp.c @@ -5,7 +5,7 @@ * License. See the file "COPYING" in the main directory of this archive * for more details. * - * Copyright (C) 2000-2005 Silicon Graphics, Inc. All rights reserved. + * Copyright (C) 2000-2006 Silicon Graphics, Inc. All rights reserved. */ #include <linux/init.h> @@ -169,6 +169,27 @@ static inline unsigned long wait_piowc(void) return ws; } +/** + * sn_migrate - SN-specific task migration actions + * @task: Task being migrated to new CPU + * + * SN2 PIO writes from separate CPUs are not guaranteed to arrive in order. + * Context switching user threads which have memory-mapped MMIO may cause + * PIOs to issue from seperate CPUs, thus the PIO writes must be drained + * from the previous CPU's Shub before execution resumes on the new CPU. + */ +void sn_migrate(struct task_struct *task) +{ + pda_t *last_pda = pdacpu(task_thread_info(task)->last_cpu); + volatile unsigned long *adr = last_pda->pio_write_status_addr; + unsigned long val = last_pda->pio_write_status_val; + + /* Drain PIO writes from old CPU's Shub */ + while (unlikely((*adr & SH_PIO_WRITE_STATUS_PENDING_WRITE_COUNT_MASK) + != val)) + cpu_relax(); +} + void sn_tlb_migrate_finish(struct mm_struct *mm) { if (mm == current->mm) |