Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net

1 files changed, 243 insertions, 57 deletions

diff --git a/lib/genalloc.c b/lib/genalloc.c
index 577ddf805975..f352cc42f4f8 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -1,8 +1,26 @@
 /*
- * Basic general purpose allocator for managing special purpose memory
- * not managed by the regular kmalloc/kfree interface.
- * Uses for this includes on-device special memory, uncached memory
- * etc.
+ * Basic general purpose allocator for managing special purpose
+ * memory, for example, memory that is not managed by the regular
+ * kmalloc/kfree interface.  Uses for this includes on-device special
+ * memory, uncached memory etc.
+ *
+ * It is safe to use the allocator in NMI handlers and other special
+ * unblockable contexts that could otherwise deadlock on locks.  This
+ * is implemented by using atomic operations and retries on any
+ * conflicts.  The disadvantage is that there may be livelocks in
+ * extreme cases.  For better scalability, one allocator can be used
+ * for each CPU.
+ *
+ * The lockless operation only works if there is enough memory
+ * available.  If new memory is added to the pool a lock has to be
+ * still taken.  So any user relying on locklessness has to ensure
+ * that sufficient memory is preallocated.
+ *
+ * The basic atomic operation of this allocator is cmpxchg on long.
+ * On architectures that don't have NMI-safe cmpxchg implementation,
+ * the allocator can NOT be used in NMI handler.  So code uses the
+ * allocator in NMI handler should depend on
+ * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
  *
  * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
  *
@@ -13,8 +31,109 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/bitmap.h>
+#include <linux/rculist.h>
+#include <linux/interrupt.h>
 #include <linux/genalloc.h>
 
+static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
+{
+        unsigned long val, nval;
+
+        nval = *addr;
+        do {
+                val = nval;
+                if (val & mask_to_set)
+                        return -EBUSY;
+                cpu_relax();
+        } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
+
+        return 0;
+}
+
+static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
+{
+        unsigned long val, nval;
+
+        nval = *addr;
+        do {
+                val = nval;
+                if ((val & mask_to_clear) != mask_to_clear)
+                        return -EBUSY;
+                cpu_relax();
+        } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
+
+        return 0;
+}
+
+/*
+ * bitmap_set_ll - set the specified number of bits at the specified position
+ * @map: pointer to a bitmap
+ * @start: a bit position in @map
+ * @nr: number of bits to set
+ *
+ * Set @nr bits start from @start in @map lock-lessly. Several users
+ * can set/clear the same bitmap simultaneously without lock. If two
+ * users set the same bit, one user will return remain bits, otherwise
+ * return 0.
+ */
+static int bitmap_set_ll(unsigned long *map, int start, int nr)
+{
+        unsigned long *p = map + BIT_WORD(start);
+        const int size = start + nr;
+        int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
+        unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
+
+        while (nr - bits_to_set >= 0) {
+                if (set_bits_ll(p, mask_to_set))
+                        return nr;
+                nr -= bits_to_set;
+                bits_to_set = BITS_PER_LONG;
+                mask_to_set = ~0UL;
+                p++;
+        }
+        if (nr) {
+                mask_to_set &= BITMAP_LAST_WORD_MASK(size);
+                if (set_bits_ll(p, mask_to_set))
+                        return nr;
+        }
+
+        return 0;
+}
+
+/*
+ * bitmap_clear_ll - clear the specified number of bits at the specified position
+ * @map: pointer to a bitmap
+ * @start: a bit position in @map
+ * @nr: number of bits to set
+ *
+ * Clear @nr bits start from @start in @map lock-lessly. Several users
+ * can set/clear the same bitmap simultaneously without lock. If two
+ * users clear the same bit, one user will return remain bits,
+ * otherwise return 0.
+ */
+static int bitmap_clear_ll(unsigned long *map, int start, int nr)
+{
+        unsigned long *p = map + BIT_WORD(start);
+        const int size = start + nr;
+        int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+        unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+        while (nr - bits_to_clear >= 0) {
+                if (clear_bits_ll(p, mask_to_clear))
+                        return nr;
+                nr -= bits_to_clear;
+                bits_to_clear = BITS_PER_LONG;
+                mask_to_clear = ~0UL;
+                p++;
+        }
+        if (nr) {
+                mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+                if (clear_bits_ll(p, mask_to_clear))
+                        return nr;
+        }
+
+        return 0;
+}
 
 /**
  * gen_pool_create - create a new special memory pool
@@ -30,7 +149,7 @@ struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
 
         pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
         if (pool != NULL) {
-                rwlock_init(&pool->lock);
+                spin_lock_init(&pool->lock);
                 INIT_LIST_HEAD(&pool->chunks);
                 pool->min_alloc_order = min_alloc_order;
         }
@@ -63,14 +182,14 @@ int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phy
         if (unlikely(chunk == NULL))
                 return -ENOMEM;
 
-        spin_lock_init(&chunk->lock);
         chunk->phys_addr = phys;
         chunk->start_addr = virt;
         chunk->end_addr = virt + size;
+        atomic_set(&chunk->avail, size);
 
-        write_lock(&pool->lock);
-        list_add(&chunk->next_chunk, &pool->chunks);
-        write_unlock(&pool->lock);
+        spin_lock(&pool->lock);
+        list_add_rcu(&chunk->next_chunk, &pool->chunks);
+        spin_unlock(&pool->lock);
 
         return 0;
 }
@@ -85,19 +204,19 @@ EXPORT_SYMBOL(gen_pool_add_virt);
  */
 phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
 {
-        struct list_head *_chunk;
         struct gen_pool_chunk *chunk;
+        phys_addr_t paddr = -1;
 
-        read_lock(&pool->lock);
-        list_for_each(_chunk, &pool->chunks) {
-                chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
-
-                if (addr >= chunk->start_addr && addr < chunk->end_addr)
-                        return chunk->phys_addr + addr - chunk->start_addr;
+        rcu_read_lock();
+        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
+                if (addr >= chunk->start_addr && addr < chunk->end_addr) {
+                        paddr = chunk->phys_addr + (addr - chunk->start_addr);
+                        break;
+                }
         }
-        read_unlock(&pool->lock);
+        rcu_read_unlock();
 
-        return -1;
+        return paddr;
 }
 EXPORT_SYMBOL(gen_pool_virt_to_phys);
 
@@ -115,7 +234,6 @@ void gen_pool_destroy(struct gen_pool *pool)
         int order = pool->min_alloc_order;
         int bit, end_bit;
 
-
         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
                 list_del(&chunk->next_chunk);
@@ -137,44 +255,50 @@ EXPORT_SYMBOL(gen_pool_destroy);
  * @size: number of bytes to allocate from the pool
  *
  * Allocate the requested number of bytes from the specified pool.
- * Uses a first-fit algorithm.
+ * Uses a first-fit algorithm. Can not be used in NMI handler on
+ * architectures without NMI-safe cmpxchg implementation.
  */
 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 {
-        struct list_head *_chunk;
         struct gen_pool_chunk *chunk;
-        unsigned long addr, flags;
+        unsigned long addr = 0;
         int order = pool->min_alloc_order;
-        int nbits, start_bit, end_bit;
+        int nbits, start_bit = 0, end_bit, remain;
+
+#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+        BUG_ON(in_nmi());
+#endif
 
         if (size == 0)
                 return 0;
 
         nbits = (size + (1UL << order) - 1) >> order;
-
-        read_lock(&pool->lock);
-        list_for_each(_chunk, &pool->chunks) {
-                chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
+        rcu_read_lock();
+        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
+                if (size > atomic_read(&chunk->avail))
+                        continue;
 
                 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
-
-                spin_lock_irqsave(&chunk->lock, flags);
-                start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, 0,
-                                                nbits, 0);
-                if (start_bit >= end_bit) {
-                        spin_unlock_irqrestore(&chunk->lock, flags);
+retry:
+                start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit,
+                                                       start_bit, nbits, 0);
+                if (start_bit >= end_bit)
                         continue;
+                remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
+                if (remain) {
+                        remain = bitmap_clear_ll(chunk->bits, start_bit,
+                                                 nbits - remain);
+                        BUG_ON(remain);
+                        goto retry;
                 }
 
                 addr = chunk->start_addr + ((unsigned long)start_bit << order);
-
-                bitmap_set(chunk->bits, start_bit, nbits);
-                spin_unlock_irqrestore(&chunk->lock, flags);
-                read_unlock(&pool->lock);
-                return addr;
+                size = nbits << order;
+                atomic_sub(size, &chunk->avail);
+                break;
         }
-        read_unlock(&pool->lock);
-        return 0;
+        rcu_read_unlock();
+        return addr;
 }
 EXPORT_SYMBOL(gen_pool_alloc);
 
@@ -184,33 +308,95 @@ EXPORT_SYMBOL(gen_pool_alloc);
  * @addr: starting address of memory to free back to pool
  * @size: size in bytes of memory to free
  *
- * Free previously allocated special memory back to the specified pool.
+ * Free previously allocated special memory back to the specified
+ * pool.  Can not be used in NMI handler on architectures without
+ * NMI-safe cmpxchg implementation.
  */
 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 {
-        struct list_head *_chunk;
         struct gen_pool_chunk *chunk;
-        unsigned long flags;
         int order = pool->min_alloc_order;
-        int bit, nbits;
+        int start_bit, nbits, remain;
 
-        nbits = (size + (1UL << order) - 1) >> order;
-
-        read_lock(&pool->lock);
-        list_for_each(_chunk, &pool->chunks) {
-                chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
+#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+        BUG_ON(in_nmi());
+#endif
 
+        nbits = (size + (1UL << order) - 1) >> order;
+        rcu_read_lock();
+        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
                 if (addr >= chunk->start_addr && addr < chunk->end_addr) {
                         BUG_ON(addr + size > chunk->end_addr);
-                        spin_lock_irqsave(&chunk->lock, flags);
-                        bit = (addr - chunk->start_addr) >> order;
-                        while (nbits--)
-                                __clear_bit(bit++, chunk->bits);
-                        spin_unlock_irqrestore(&chunk->lock, flags);
-                        break;
+                        start_bit = (addr - chunk->start_addr) >> order;
+                        remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
+                        BUG_ON(remain);
+                        size = nbits << order;
+                        atomic_add(size, &chunk->avail);
+                        rcu_read_unlock();
+                        return;
                 }
         }
-        BUG_ON(nbits > 0);
-        read_unlock(&pool->lock);
+        rcu_read_unlock();
+        BUG();
 }
 EXPORT_SYMBOL(gen_pool_free);
+
+/**
+ * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
+ * @pool:       the generic memory pool
+ * @func:       func to call
+ * @data:       additional data used by @func
+ *
+ * Call @func for every chunk of generic memory pool.  The @func is
+ * called with rcu_read_lock held.
+ */
+void gen_pool_for_each_chunk(struct gen_pool *pool,
+        void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
+        void *data)
+{
+        struct gen_pool_chunk *chunk;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
+                func(pool, chunk, data);
+        rcu_read_unlock();
+}
+EXPORT_SYMBOL(gen_pool_for_each_chunk);
+
+/**
+ * gen_pool_avail - get available free space of the pool
+ * @pool: pool to get available free space
+ *
+ * Return available free space of the specified pool.
+ */
+size_t gen_pool_avail(struct gen_pool *pool)
+{
+        struct gen_pool_chunk *chunk;
+        size_t avail = 0;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
+                avail += atomic_read(&chunk->avail);
+        rcu_read_unlock();
+        return avail;
+}
+EXPORT_SYMBOL_GPL(gen_pool_avail);
+
+/**
+ * gen_pool_size - get size in bytes of memory managed by the pool
+ * @pool: pool to get size
+ *
+ * Return size in bytes of memory managed by the pool.
+ */
+size_t gen_pool_size(struct gen_pool *pool)
+{
+        struct gen_pool_chunk *chunk;
+        size_t size = 0;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
+                size += chunk->end_addr - chunk->start_addr;
+        rcu_read_unlock();
+        return size;
+}
+EXPORT_SYMBOL_GPL(gen_pool_size);