percpu: add chunk->base_addr

The only thing percpu allocator wants to know about a vmalloc area is
the base address.  Instead of requiring chunk->vm, add
chunk->base_addr which contains the necessary value.  This simplifies
the code a bit and makes the dummy first_vm unnecessary.  This change
will ease allowing a chunk to be mapped by multiple vms.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 11 insertions, 14 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index 653b02c40200..548624309f83 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -94,10 +94,11 @@ struct pcpu_chunk {
         struct list_head        list;           /* linked to pcpu_slot lists */
         int                     free_size;      /* free bytes in the chunk */
         int                     contig_hint;    /* max contiguous size hint */
-        struct vm_struct        *vm;            /* mapped vmalloc region */
+        void                    *base_addr;     /* base address of this chunk */
         int                     map_used;       /* # of map entries used */
         int                     map_alloc;      /* # of map entries allocated */
         int                     *map;           /* allocation map */
+        struct vm_struct        *vm;            /* mapped vmalloc region */
         bool                    immutable;      /* no [de]population allowed */
         unsigned long           populated[];    /* populated bitmap */
 };
@@ -196,7 +197,7 @@ static int pcpu_page_idx(unsigned int cpu, int page_idx)
 static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
                                      unsigned int cpu, int page_idx)
 {
-        return (unsigned long)chunk->vm->addr + pcpu_unit_offsets[cpu] +
+        return (unsigned long)chunk->base_addr + pcpu_unit_offsets[cpu] +
                 (page_idx << PAGE_SHIFT);
 }
 
@@ -324,7 +325,7 @@ static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
  */
 static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
 {
-        void *first_start = pcpu_first_chunk->vm->addr;
+        void *first_start = pcpu_first_chunk->base_addr;
 
         /* is it in the first chunk? */
         if (addr >= first_start && addr < first_start + pcpu_unit_size) {
@@ -1014,6 +1015,7 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
         INIT_LIST_HEAD(&chunk->list);
         chunk->free_size = pcpu_unit_size;
         chunk->contig_hint = pcpu_unit_size;
+        chunk->base_addr = chunk->vm->addr;
 
         return chunk;
 }
@@ -1103,8 +1105,8 @@ area_found:
 
         mutex_unlock(&pcpu_alloc_mutex);
 
-        /* return address relative to unit0 */
-        return __addr_to_pcpu_ptr(chunk->vm->addr + off);
+        /* return address relative to base address */
+        return __addr_to_pcpu_ptr(chunk->base_addr + off);
 
 fail_unlock:
         spin_unlock_irq(&pcpu_lock);
@@ -1213,7 +1215,7 @@ void free_percpu(void *ptr)
         spin_lock_irqsave(&pcpu_lock, flags);
 
         chunk = pcpu_chunk_addr_search(addr);
-        off = addr - chunk->vm->addr;
+        off = addr - chunk->base_addr;
 
         pcpu_free_area(chunk, off);
 
@@ -1565,7 +1567,6 @@ static void pcpu_dump_alloc_info(const char *lvl,
 int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
                                   void *base_addr)
 {
-        static struct vm_struct first_vm;
         static int smap[2], dmap[2];
         size_t dyn_size = ai->dyn_size;
         size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
@@ -1629,10 +1630,6 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
                 BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
 
-        first_vm.flags = VM_ALLOC;
-        first_vm.size = pcpu_chunk_size;
-        first_vm.addr = base_addr;
-
         /*
          * Allocate chunk slots.  The additional last slot is for
          * empty chunks.
@@ -1651,7 +1648,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
          */
         schunk = alloc_bootmem(pcpu_chunk_struct_size);
         INIT_LIST_HEAD(&schunk->list);
-        schunk->vm = &first_vm;
+        schunk->base_addr = base_addr;
         schunk->map = smap;
         schunk->map_alloc = ARRAY_SIZE(smap);
         schunk->immutable = true;
@@ -1675,7 +1672,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         if (dyn_size) {
                 dchunk = alloc_bootmem(pcpu_chunk_struct_size);
                 INIT_LIST_HEAD(&dchunk->list);
-                dchunk->vm = &first_vm;
+                dchunk->base_addr = base_addr;
                 dchunk->map = dmap;
                 dchunk->map_alloc = ARRAY_SIZE(dmap);
                 dchunk->immutable = true;
@@ -1691,7 +1688,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         pcpu_chunk_relocate(pcpu_first_chunk, -1);
 
         /* we're done */
-        pcpu_base_addr = schunk->vm->addr;
+        pcpu_base_addr = base_addr;
         return 0;
 }