1 files changed, 115 insertions, 10 deletions

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index f100ce20b16b..0bfc1ef11259 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -38,6 +38,7 @@
 #include <linux/vmalloc.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
+#include <linux/hardirq.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
@@ -426,10 +427,8 @@ static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
         nflags = *pflags;
         do {
                 flags = nflags;
-                if (flags & (GTF_reading|GTF_writing)) {
-                        printk(KERN_ALERT "WARNING: g.e. still in use!\n");
+                if (flags & (GTF_reading|GTF_writing))
                         return 0;
-                }
         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 
         return 1;
@@ -458,12 +457,103 @@ static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
         return 1;
 }
 
-int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
+static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 {
         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 }
+
+int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
+{
+        if (_gnttab_end_foreign_access_ref(ref, readonly))
+                return 1;
+        pr_warn("WARNING: g.e. %#x still in use!\n", ref);
+        return 0;
+}
 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 
+struct deferred_entry {
+        struct list_head list;
+        grant_ref_t ref;
+        bool ro;
+        uint16_t warn_delay;
+        struct page *page;
+};
+static LIST_HEAD(deferred_list);
+static void gnttab_handle_deferred(unsigned long);
+static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
+
+static void gnttab_handle_deferred(unsigned long unused)
+{
+        unsigned int nr = 10;
+        struct deferred_entry *first = NULL;
+        unsigned long flags;
+
+        spin_lock_irqsave(&gnttab_list_lock, flags);
+        while (nr--) {
+                struct deferred_entry *entry
+                        = list_first_entry(&deferred_list,
+                                           struct deferred_entry, list);
+
+                if (entry == first)
+                        break;
+                list_del(&entry->list);
+                spin_unlock_irqrestore(&gnttab_list_lock, flags);
+                if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
+                        put_free_entry(entry->ref);
+                        if (entry->page) {
+                                pr_debug("freeing g.e. %#x (pfn %#lx)\n",
+                                         entry->ref, page_to_pfn(entry->page));
+                                __free_page(entry->page);
+                        } else
+                                pr_info("freeing g.e. %#x\n", entry->ref);
+                        kfree(entry);
+                        entry = NULL;
+                } else {
+                        if (!--entry->warn_delay)
+                                pr_info("g.e. %#x still pending\n",
+                                        entry->ref);
+                        if (!first)
+                                first = entry;
+                }
+                spin_lock_irqsave(&gnttab_list_lock, flags);
+                if (entry)
+                        list_add_tail(&entry->list, &deferred_list);
+                else if (list_empty(&deferred_list))
+                        break;
+        }
+        if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
+                deferred_timer.expires = jiffies + HZ;
+                add_timer(&deferred_timer);
+        }
+        spin_unlock_irqrestore(&gnttab_list_lock, flags);
+}
+
+static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
+                                struct page *page)
+{
+        struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
+        const char *what = KERN_WARNING "leaking";
+
+        if (entry) {
+                unsigned long flags;
+
+                entry->ref = ref;
+                entry->ro = readonly;
+                entry->page = page;
+                entry->warn_delay = 60;
+                spin_lock_irqsave(&gnttab_list_lock, flags);
+                list_add_tail(&entry->list, &deferred_list);
+                if (!timer_pending(&deferred_timer)) {
+                        deferred_timer.expires = jiffies + HZ;
+                        add_timer(&deferred_timer);
+                }
+                spin_unlock_irqrestore(&gnttab_list_lock, flags);
+                what = KERN_DEBUG "deferring";
+        }
+        printk("%s g.e. %#x (pfn %#lx)\n",
+               what, ref, page ? page_to_pfn(page) : -1);
+}
+
 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
                                unsigned long page)
 {
@@ -471,12 +561,9 @@ void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
                 put_free_entry(ref);
                 if (page != 0)
                         free_page(page);
-        } else {
-                /* XXX This needs to be fixed so that the ref and page are
-                   placed on a list to be freed up later. */
-                printk(KERN_WARNING
-                       "WARNING: leaking g.e. and page still in use!\n");
-        }
+        } else
+                gnttab_add_deferred(ref, readonly,
+                                    page ? virt_to_page(page) : NULL);
 }
 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 
@@ -741,6 +828,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
                     struct page **pages, unsigned int count)
 {
         int i, ret;
+        bool lazy = false;
         pte_t *pte;
         unsigned long mfn;
 
@@ -751,6 +839,11 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
         if (xen_feature(XENFEAT_auto_translated_physmap))
                 return ret;
 
+        if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
+                arch_enter_lazy_mmu_mode();
+                lazy = true;
+        }
+
         for (i = 0; i < count; i++) {
                 /* Do not add to override if the map failed. */
                 if (map_ops[i].status)
@@ -769,6 +862,9 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
                         return ret;
         }
 
+        if (lazy)
+                arch_leave_lazy_mmu_mode();
+
         return ret;
 }
 EXPORT_SYMBOL_GPL(gnttab_map_refs);
@@ -777,6 +873,7 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
                       struct page **pages, unsigned int count, bool clear_pte)
 {
         int i, ret;
+        bool lazy = false;
 
         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
         if (ret)
@@ -785,12 +882,20 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
         if (xen_feature(XENFEAT_auto_translated_physmap))
                 return ret;
 
+        if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
+                arch_enter_lazy_mmu_mode();
+                lazy = true;
+        }
+
         for (i = 0; i < count; i++) {
                 ret = m2p_remove_override(pages[i], clear_pte);
                 if (ret)
                         return ret;
         }
 
+        if (lazy)
+                arch_leave_lazy_mmu_mode();
+
         return ret;
 }
 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);