From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
The gmap notifier list and the gmap list in the mm_struct change rarely.
Use RCU to optimize the reader of these lists.
Reviewed-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/include/asm/gmap.h | 1 +
arch/s390/include/asm/mmu.h | 11 +++++++----
arch/s390/include/asm/mmu_context.h | 3 ++-
arch/s390/mm/gmap.c | 39 ++++++++++++++++++++++---------------
arch/s390/mm/pgalloc.c | 16 +++++++--------
5 files changed, 41 insertions(+), 29 deletions(-)
diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index bc0eadf..2cf49624 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -39,6 +39,7 @@ struct gmap {
*/
struct gmap_notifier {
struct list_head list;
+ struct rcu_head rcu;
void (*notifier_call)(struct gmap *gmap, unsigned long start,
unsigned long end);
};
diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h
index 081b2ad..b941528 100644
--- a/arch/s390/include/asm/mmu.h
+++ b/arch/s390/include/asm/mmu.h
@@ -8,8 +8,9 @@ typedef struct {
cpumask_t cpu_attach_mask;
atomic_t attach_count;
unsigned int flush_mm;
- spinlock_t list_lock;
+ spinlock_t pgtable_lock;
struct list_head pgtable_list;
+ spinlock_t gmap_lock;
struct list_head gmap_list;
unsigned long asce;
unsigned long asce_limit;
@@ -22,9 +23,11 @@ typedef struct {
unsigned int use_skey:1;
} mm_context_t;
-#define INIT_MM_CONTEXT(name) \
- .context.list_lock = __SPIN_LOCK_UNLOCKED(name.context.list_lock), \
- .context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \
+#define INIT_MM_CONTEXT(name) \
+ .context.pgtable_lock = \
+ __SPIN_LOCK_UNLOCKED(name.context.pgtable_lock), \
+ .context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \
+ .context.gmap_lock = __SPIN_LOCK_UNLOCKED(name.context.gmap_lock), \
.context.gmap_list = LIST_HEAD_INIT(name.context.gmap_list),
static inline int tprot(unsigned long addr)
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index c837b79..3ce3854 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -15,8 +15,9 @@
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
- spin_lock_init(&mm->context.list_lock);
+ spin_lock_init(&mm->context.pgtable_lock);
INIT_LIST_HEAD(&mm->context.pgtable_list);
+ spin_lock_init(&mm->context.gmap_lock);
INIT_LIST_HEAD(&mm->context.gmap_list);
cpumask_clear(&mm->context.cpu_attach_mask);
atomic_set(&mm->context.attach_count, 0);
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index b5820bf..8b56423 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -70,9 +70,9 @@ struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit)
gmap->asce = atype | _ASCE_TABLE_LENGTH |
_ASCE_USER_BITS | __pa(table);
gmap->asce_end = limit;
- down_write(&mm->mmap_sem);
- list_add(&gmap->list, &mm->context.gmap_list);
- up_write(&mm->mmap_sem);
+ spin_lock(&mm->context.gmap_lock);
+ list_add_rcu(&gmap->list, &mm->context.gmap_list);
+ spin_unlock(&mm->context.gmap_lock);
return gmap;
out_free:
@@ -128,14 +128,16 @@ void gmap_free(struct gmap *gmap)
else
__tlb_flush_global();
+ spin_lock(&gmap->mm->context.gmap_lock);
+ list_del_rcu(&gmap->list);
+ spin_unlock(&gmap->mm->context.gmap_lock);
+ synchronize_rcu();
+
/* Free all segment & region tables. */
list_for_each_entry_safe(page, next, &gmap->crst_list, lru)
__free_pages(page, 2);
gmap_radix_tree_free(&gmap->guest_to_host);
gmap_radix_tree_free(&gmap->host_to_guest);
- down_write(&gmap->mm->mmap_sem);
- list_del(&gmap->list);
- up_write(&gmap->mm->mmap_sem);
kfree(gmap);
}
EXPORT_SYMBOL_GPL(gmap_free);
@@ -369,11 +371,13 @@ void gmap_unlink(struct mm_struct *mm, unsigned long *table,
struct gmap *gmap;
int flush;
- list_for_each_entry(gmap, &mm->context.gmap_list, list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
flush = __gmap_unlink_by_vmaddr(gmap, vmaddr);
if (flush)
gmap_flush_tlb(gmap);
}
+ rcu_read_unlock();
}
/**
@@ -555,7 +559,7 @@ static DEFINE_SPINLOCK(gmap_notifier_lock);
void gmap_register_ipte_notifier(struct gmap_notifier *nb)
{
spin_lock(&gmap_notifier_lock);
- list_add(&nb->list, &gmap_notifier_list);
+ list_add_rcu(&nb->list, &gmap_notifier_list);
spin_unlock(&gmap_notifier_lock);
}
EXPORT_SYMBOL_GPL(gmap_register_ipte_notifier);
@@ -567,8 +571,9 @@ EXPORT_SYMBOL_GPL(gmap_register_ipte_notifier);
void gmap_unregister_ipte_notifier(struct gmap_notifier *nb)
{
spin_lock(&gmap_notifier_lock);
- list_del_init(&nb->list);
+ list_del_rcu(&nb->list);
spin_unlock(&gmap_notifier_lock);
+ synchronize_rcu();
}
EXPORT_SYMBOL_GPL(gmap_unregister_ipte_notifier);
@@ -662,16 +667,18 @@ void ptep_notify(struct mm_struct *mm, unsigned long vmaddr, pte_t *pte)
offset = ((unsigned long) pte) & (255 * sizeof(pte_t));
offset = offset * (4096 / sizeof(pte_t));
- spin_lock(&gmap_notifier_lock);
- list_for_each_entry(gmap, &mm->context.gmap_list, list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
+ spin_lock(&gmap->guest_table_lock);
table = radix_tree_lookup(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
- if (!table)
- continue;
- gaddr = __gmap_segment_gaddr(table) + offset;
- gmap_call_notifier(gmap, gaddr, gaddr + PAGE_SIZE - 1);
+ if (table)
+ gaddr = __gmap_segment_gaddr(table) + offset;
+ spin_unlock(&gmap->guest_table_lock);
+ if (table)
+ gmap_call_notifier(gmap, gaddr, gaddr + PAGE_SIZE - 1);
}
- spin_unlock(&gmap_notifier_lock);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(ptep_notify);
diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
index e8b5962..7be1f94 100644
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -149,7 +149,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
/* Try to get a fragment of a 4K page as a 2K page table */
if (!mm_alloc_pgste(mm)) {
table = NULL;
- spin_lock_bh(&mm->context.list_lock);
+ spin_lock_bh(&mm->context.pgtable_lock);
if (!list_empty(&mm->context.pgtable_list)) {
page = list_first_entry(&mm->context.pgtable_list,
struct page, lru);
@@ -164,7 +164,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
list_del(&page->lru);
}
}
- spin_unlock_bh(&mm->context.list_lock);
+ spin_unlock_bh(&mm->context.pgtable_lock);
if (table)
return table;
}
@@ -187,9 +187,9 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
/* Return the first 2K fragment of the page */
atomic_set(&page->_mapcount, 1);
clear_table(table, _PAGE_INVALID, PAGE_SIZE);
- spin_lock_bh(&mm->context.list_lock);
+ spin_lock_bh(&mm->context.pgtable_lock);
list_add(&page->lru, &mm->context.pgtable_list);
- spin_unlock_bh(&mm->context.list_lock);
+ spin_unlock_bh(&mm->context.pgtable_lock);
}
return table;
}
@@ -203,13 +203,13 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
if (!mm_alloc_pgste(mm)) {
/* Free 2K page table fragment of a 4K page */
bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
- spin_lock_bh(&mm->context.list_lock);
+ spin_lock_bh(&mm->context.pgtable_lock);
mask = atomic_xor_bits(&page->_mapcount, 1U << bit);
if (mask & 3)
list_add(&page->lru, &mm->context.pgtable_list);
else
list_del(&page->lru);
- spin_unlock_bh(&mm->context.list_lock);
+ spin_unlock_bh(&mm->context.pgtable_lock);
if (mask != 0)
return;
}
@@ -235,13 +235,13 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table,
return;
}
bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
- spin_lock_bh(&mm->context.list_lock);
+ spin_lock_bh(&mm->context.pgtable_lock);
mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);
if (mask & 3)
list_add_tail(&page->lru, &mm->context.pgtable_list);
else
list_del(&page->lru);
- spin_unlock_bh(&mm->context.list_lock);
+ spin_unlock_bh(&mm->context.pgtable_lock);
table = (unsigned long *) (__pa(table) | (1U << bit));
tlb_remove_table(tlb, table);
}
--
2.5.5
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