From: Tony Luck <tony.luck@intel.com>
Date: Tue, 21 Mar 2006 16:21:26 +0000 (-0800)
Subject: Pull sn2-mmio-writes into release branch
X-Git-Tag: v2.6.17-rc1~1130^2^2~3
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=409761bb6a06bd61e2d8e27a1af534371d9537ed;p=linux-2.6

Pull sn2-mmio-writes into release branch

Hand-fixed conflicts:
	include/asm-ia64/machvec_sn2.h

Signed-off-by: Tony Luck <tony.luck@intel.com>
---

409761bb6a06bd61e2d8e27a1af534371d9537ed
diff --cc arch/ia64/sn/kernel/sn2/sn2_smp.c
index b2e1e746b4,1b33fd5e4e..d9d306c79f
--- a/arch/ia64/sn/kernel/sn2/sn2_smp.c
+++ b/arch/ia64/sn/kernel/sn2/sn2_smp.c
@@@ -90,13 -166,33 +90,34 @@@ static inline unsigned long wait_piowc(
  	do {
  		cpu_relax();
  	} while (((ws = *piows) & SH_PIO_WRITE_STATUS_PENDING_WRITE_COUNT_MASK) != zeroval);
 -	return ws;
 +	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)
  {
 -	if (mm == current->mm)
 +	/* flush_tlb_mm is inefficient if more than 1 users of mm */
 +	if (mm == current->mm && mm && atomic_read(&mm->mm_users) == 1)
  		flush_tlb_mm(mm);
  }