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author | Steven Whitehouse <swhiteho@redhat.com> | 2006-03-31 15:34:58 -0500 |
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committer | Steven Whitehouse <swhiteho@redhat.com> | 2006-03-31 15:34:58 -0500 |
commit | 86579dd06deecfa6ac88d5e84e4d63c397cd6f6d (patch) | |
tree | b4475d3ccde53015ad84a06e4e55e64591171b75 /arch/ia64/sn/kernel/sn2/sn2_smp.c | |
parent | 7ea9ea832212c4a755650f7c7cc1ff0b63292a41 (diff) | |
parent | a0f067802576d4eb4c65d40b8ee7d6ea3c81dd61 (diff) | |
download | linux-stable-86579dd06deecfa6ac88d5e84e4d63c397cd6f6d.tar.gz linux-stable-86579dd06deecfa6ac88d5e84e4d63c397cd6f6d.tar.bz2 linux-stable-86579dd06deecfa6ac88d5e84e4d63c397cd6f6d.zip |
Merge branch 'master'
Diffstat (limited to 'arch/ia64/sn/kernel/sn2/sn2_smp.c')
-rw-r--r-- | arch/ia64/sn/kernel/sn2/sn2_smp.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c index b2e1e746b47f..d9d306c79f2d 100644 --- a/arch/ia64/sn/kernel/sn2/sn2_smp.c +++ b/arch/ia64/sn/kernel/sn2/sn2_smp.c @@ -93,6 +93,27 @@ static inline unsigned long wait_piowc(void) return (ws & SH_PIO_WRITE_STATUS_WRITE_DEADLOCK_MASK) != 0; } +/** + * 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) { /* flush_tlb_mm is inefficient if more than 1 users of mm */ |