1 files changed, 41 insertions, 24 deletions

diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c
index c08a4152ee8f..04ac155d3a07 100644
--- a/drivers/char/mspec.c
+++ b/drivers/char/mspec.c
@@ -67,7 +67,7 @@
 /*
  * Page types allocated by the device.
  */
-enum {
+enum mspec_page_type {
         MSPEC_FETCHOP = 1,
         MSPEC_CACHED,
         MSPEC_UNCACHED
@@ -83,15 +83,25 @@ static int is_sn2;
  * One of these structures is allocated when an mspec region is mmaped. The
  * structure is pointed to by the vma->vm_private_data field in the vma struct.
  * This structure is used to record the addresses of the mspec pages.
+ * This structure is shared by all vma's that are split off from the
+ * original vma when split_vma()'s are done.
+ *
+ * The refcnt is incremented atomically because mm->mmap_sem does not
+ * protect in fork case where multiple tasks share the vma_data.
  */
 struct vma_data {
         atomic_t refcnt;        /* Number of vmas sharing the data. */
-        spinlock_t lock;        /* Serialize access to the vma. */
+        spinlock_t lock;        /* Serialize access to this structure. */
         int count;              /* Number of pages allocated. */
-        int type;               /* Type of pages allocated. */
+        enum mspec_page_type type; /* Type of pages allocated. */
+        int flags;              /* See VMD_xxx below. */
+        unsigned long vm_start; /* Original (unsplit) base. */
+        unsigned long vm_end;   /* Original (unsplit) end. */
         unsigned long maddr[0]; /* Array of MSPEC addresses. */
 };
 
+#define VMD_VMALLOCED 0x1       /* vmalloc'd rather than kmalloc'd */
+
 /* used on shub2 to clear FOP cache in the HUB */
 static unsigned long scratch_page[MAX_NUMNODES];
 #define SH2_AMO_CACHE_ENTRIES   4
@@ -129,8 +139,8 @@ mspec_zero_block(unsigned long addr, int len)
  * mspec_open
  *
  * Called when a device mapping is created by a means other than mmap
- * (via fork, etc.).  Increments the reference count on the underlying
- * mspec data so it is not freed prematurely.
+ * (via fork, munmap, etc.).  Increments the reference count on the
+ * underlying mspec data so it is not freed prematurely.
  */
 static void
 mspec_open(struct vm_area_struct *vma)
@@ -145,43 +155,43 @@ mspec_open(struct vm_area_struct *vma)
  * mspec_close
  *
  * Called when unmapping a device mapping. Frees all mspec pages
- * belonging to the vma.
+ * belonging to all the vma's sharing this vma_data structure.
  */
 static void
 mspec_close(struct vm_area_struct *vma)
 {
         struct vma_data *vdata;
-        int i, pages, result, vdata_size;
+        int index, last_index;
+        unsigned long my_page;
 
         vdata = vma->vm_private_data;
+
         if (!atomic_dec_and_test(&vdata->refcnt))
                 return;
 
-        pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
-        vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
-        for (i = 0; i < pages; i++) {
-                if (vdata->maddr[i] == 0)
+        last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
+        for (index = 0; index < last_index; index++) {
+                if (vdata->maddr[index] == 0)
                         continue;
                 /*
                  * Clear the page before sticking it back
                  * into the pool.
                  */
-                result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
-                if (!result)
-                        uncached_free_page(vdata->maddr[i]);
+                my_page = vdata->maddr[index];
+                vdata->maddr[index] = 0;
+                if (!mspec_zero_block(my_page, PAGE_SIZE))
+                        uncached_free_page(my_page);
                 else
                         printk(KERN_WARNING "mspec_close(): "
-                               "failed to zero page %i\n",
-                               result);
+                               "failed to zero page %ld\n", my_page);
         }
 
-        if (vdata_size <= PAGE_SIZE)
-                kfree(vdata);
-        else
+        if (vdata->flags & VMD_VMALLOCED)
                 vfree(vdata);
+        else
+                kfree(vdata);
 }
 
-
 /*
  * mspec_nopfn
  *
@@ -195,7 +205,8 @@ mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
         int index;
         struct vma_data *vdata = vma->vm_private_data;
 
-        index = (address - vma->vm_start) >> PAGE_SHIFT;
+        BUG_ON(address < vdata->vm_start || address >= vdata->vm_end);
+        index = (address - vdata->vm_start) >> PAGE_SHIFT;
         maddr = (volatile unsigned long) vdata->maddr[index];
         if (maddr == 0) {
                 maddr = uncached_alloc_page(numa_node_id());
@@ -237,10 +248,11 @@ static struct vm_operations_struct mspec_vm_ops = {
  * underlying pages.
  */
 static int
-mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
+mspec_mmap(struct file *file, struct vm_area_struct *vma,
+                                        enum mspec_page_type type)
 {
         struct vma_data *vdata;
-        int pages, vdata_size;
+        int pages, vdata_size, flags = 0;
 
         if (vma->vm_pgoff != 0)
                 return -EINVAL;
@@ -255,12 +267,17 @@ mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
         if (vdata_size <= PAGE_SIZE)
                 vdata = kmalloc(vdata_size, GFP_KERNEL);
-        else
+        else {
                 vdata = vmalloc(vdata_size);
+                flags = VMD_VMALLOCED;
+        }
         if (!vdata)
                 return -ENOMEM;
         memset(vdata, 0, vdata_size);
 
+        vdata->vm_start = vma->vm_start;
+        vdata->vm_end = vma->vm_end;
+        vdata->flags = flags;
         vdata->type = type;
         spin_lock_init(&vdata->lock);
         vdata->refcnt = ATOMIC_INIT(1);