Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[karo-tx-linux.git] / arch / powerpc / mm / hash_native_64.c

diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
index 13befa35d8a8ecdd31611aadb42c6be206ba743e..c8822af10a587389999473171db475eb5462714b 100644 (file)
--- a/arch/powerpc/mm/hash_native_64.c
+++ b/arch/powerpc/mm/hash_native_64.c
@@ -582,13 +582,21 @@ static void hpte_decode(struct hash_pte *hpte, unsigned long slot,
  * be when they isi), and we are the only one left.  We rely on our kernel
  * mapping being 0xC0's and the hardware ignoring those two real bits.
  *
+ * This must be called with interrupts disabled.
+ *
+ * Taking the native_tlbie_lock is unsafe here due to the possibility of
+ * lockdep being on. On pre POWER5 hardware, not taking the lock could
+ * cause deadlock. POWER5 and newer not taking the lock is fine. This only
+ * gets called during boot before secondary CPUs have come up and during
+ * crashdump and all bets are off anyway.
+ *
  * TODO: add batching support when enabled.  remember, no dynamic memory here,
  * athough there is the control page available...
  */
 static void native_hpte_clear(void)
 {
        unsigned long vpn = 0;
-       unsigned long slot, slots, flags;
+       unsigned long slot, slots;
        struct hash_pte *hptep = htab_address;
        unsigned long hpte_v;
        unsigned long pteg_count;
@@ -596,13 +604,6 @@ static void native_hpte_clear(void)
 
        pteg_count = htab_hash_mask + 1;
 
-       local_irq_save(flags);
-
-       /* we take the tlbie lock and hold it.  Some hardware will
-        * deadlock if we try to tlbie from two processors at once.
-        */
-       raw_spin_lock(&native_tlbie_lock);
-
        slots = pteg_count * HPTES_PER_GROUP;
 
        for (slot = 0; slot < slots; slot++, hptep++) {
@@ -614,8 +615,8 @@ static void native_hpte_clear(void)
                hpte_v = be64_to_cpu(hptep->v);
 
                /*
-                * Call __tlbie() here rather than tlbie() since we
-                * already hold the native_tlbie_lock.
+                * Call __tlbie() here rather than tlbie() since we can't take the
+                * native_tlbie_lock.
                 */
                if (hpte_v & HPTE_V_VALID) {
                        hpte_decode(hptep, slot, &psize, &apsize, &ssize, &vpn);
@@ -625,8 +626,6 @@ static void native_hpte_clear(void)
        }
 
        asm volatile("eieio; tlbsync; ptesync":::"memory");
-       raw_spin_unlock(&native_tlbie_lock);
-       local_irq_restore(flags);
 }
 
 /*