linux-kernel - [PATCH] genalloc: Make the avail variable an atomic64

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Message-Id: <1508945574-25984-1-git-send-email-sbates@raithlin.com>
Date:   Wed, 25 Oct 2017 09:32:54 -0600
From:   sbates@...thlin.com
To:     corbet@....net, sbates@...thlin.com,
        mathieu.desnoyers@...icios.com, danielmentz@...gle.com,
        akpm@...ux-foundation.org, will.deacon@....com,
        linux-kernel@...r.kernel.org, logang@...tatee.com
Subject: [PATCH] genalloc: Make the avail variable an atomic64_t

From: Stephen Bates <sbates@...thlin.com>

If the amount of resources allocated to a gen_pool exceeds 2^32 then
the avail atomic overflows and this causes problems when clients try
and borrow resources from the pool.

Add the <linux/atomic.h> header to pull in atomic64 operations on
platforms that do not support them natively.

Signed-off-by: Stephen Bates <sbates@...thlin.com>
---
 include/linux/genalloc.h |  3 ++-
 lib/genalloc.c           | 10 +++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 6dfec4d..b327c31 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -32,6 +32,7 @@
 
 #include <linux/types.h>
 #include <linux/spinlock_types.h>
+#include <linux/atomic.h>
 
 struct device;
 struct device_node;
@@ -71,7 +72,7 @@ struct gen_pool {
  */
 struct gen_pool_chunk {
 	struct list_head next_chunk;	/* next chunk in pool */
-	atomic_t avail;
+	atomic64_t avail;
 	phys_addr_t phys_addr;		/* physical starting address of memory chunk */
 	unsigned long start_addr;	/* start address of memory chunk */
 	unsigned long end_addr;		/* end address of memory chunk (inclusive) */
diff --git a/lib/genalloc.c b/lib/genalloc.c
index 144fe6b..a97df2b 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -194,7 +194,7 @@ int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phy
 	chunk->phys_addr = phys;
 	chunk->start_addr = virt;
 	chunk->end_addr = virt + size - 1;
-	atomic_set(&chunk->avail, size);
+	atomic64_set(&chunk->avail, size);
 
 	spin_lock(&pool->lock);
 	list_add_rcu(&chunk->next_chunk, &pool->chunks);
@@ -304,7 +304,7 @@ unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
 	nbits = (size + (1UL << order) - 1) >> order;
 	rcu_read_lock();
 	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
-		if (size > atomic_read(&chunk->avail))
+		if (size > atomic64_read(&chunk->avail))
 			continue;
 
 		start_bit = 0;
@@ -324,7 +324,7 @@ unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
 
 		addr = chunk->start_addr + ((unsigned long)start_bit << order);
 		size = nbits << order;
-		atomic_sub(size, &chunk->avail);
+		atomic64_sub(size, &chunk->avail);
 		break;
 	}
 	rcu_read_unlock();
@@ -390,7 +390,7 @@ void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 			remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 			BUG_ON(remain);
 			size = nbits << order;
-			atomic_add(size, &chunk->avail);
+			atomic64_add(size, &chunk->avail);
 			rcu_read_unlock();
 			return;
 		}
@@ -464,7 +464,7 @@ size_t gen_pool_avail(struct gen_pool *pool)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
-		avail += atomic_read(&chunk->avail);
+		avail += atomic64_read(&chunk->avail);
 	rcu_read_unlock();
 	return avail;
 }
-- 
2.7.4