From e549372b384c06403286c224856d3c7a35e2a078 Mon Sep 17 00:00:00 2001
From: Jimi Xenidis <jimix@pobox.com>
Date: Tue, 28 Feb 2012 13:27:07 +0000
Subject: [PATCH] --- yaml --- r: 292486 b: refs/heads/master c:
 de801de139ba2a2f2c74393ea00a321477ecc0dc h: refs/heads/master v: v3

---
 [refs]                        |  2 +-
 trunk/arch/powerpc/mm/icswx.c | 23 +++++++++++++++++++++--
 trunk/arch/powerpc/mm/icswx.h |  6 ++++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index cd72d1eeb46b..f4c2d762919f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a6cf7ed5119fb22f54584a9f867b638edd3c4384
+refs/heads/master: de801de139ba2a2f2c74393ea00a321477ecc0dc
diff --git a/trunk/arch/powerpc/mm/icswx.c b/trunk/arch/powerpc/mm/icswx.c
index 5d9a59eaad93..8cdbd8634a58 100644
--- a/trunk/arch/powerpc/mm/icswx.c
+++ b/trunk/arch/powerpc/mm/icswx.c
@@ -163,7 +163,7 @@ EXPORT_SYMBOL_GPL(drop_cop);
 
 static int acop_use_cop(int ct)
 {
-	/* todo */
+	/* There is no alternate policy, yet */
 	return -1;
 }
 
@@ -227,11 +227,30 @@ int acop_handle_fault(struct pt_regs *regs, unsigned long address,
 		ct = (ccw >> 16) & 0x3f;
 	}
 
+	/*
+	 * We could be here because another thread has enabled acop
+	 * but the ACOP register has yet to be updated.
+	 *
+	 * This should have been taken care of by the IPI to sync all
+	 * the threads (see smp_call_function(sync_cop, mm, 1)), but
+	 * that could take forever if there are a significant amount
+	 * of threads.
+	 *
+	 * Given the number of threads on some of these systems,
+	 * perhaps this is the best way to sync ACOP rather than whack
+	 * every thread with an IPI.
+	 */
+	if ((acop_copro_type_bit(ct) & current->active_mm->context.acop) != 0) {
+		sync_cop(current->active_mm);
+		return 0;
+	}
+
+	/* check for alternate policy */
 	if (!acop_use_cop(ct))
 		return 0;
 
 	/* at this point the CT is unknown to the system */
-	pr_warn("%s[%d]: Coprocessor %d is unavailable",
+	pr_warn("%s[%d]: Coprocessor %d is unavailable\n",
 		current->comm, current->pid, ct);
 
 	/* get inst if we don't already have it */
diff --git a/trunk/arch/powerpc/mm/icswx.h b/trunk/arch/powerpc/mm/icswx.h
index 42176bd0884c..6dedc08e62c8 100644
--- a/trunk/arch/powerpc/mm/icswx.h
+++ b/trunk/arch/powerpc/mm/icswx.h
@@ -59,4 +59,10 @@ extern void free_cop_pid(int free_pid);
 
 extern int acop_handle_fault(struct pt_regs *regs, unsigned long address,
 			     unsigned long error_code);
+
+static inline u64 acop_copro_type_bit(unsigned int type)
+{
+	return 1ULL << (63 - type);
+}
+
 #endif /* !_ARCH_POWERPC_MM_ICSWX_H_ */