linux-kernel - [PATCH 4.4 077/105] lib/genalloc.c: make the avail variable an atomic_long

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Message-Id: <20171215092309.889323597@linuxfoundation.org>
Date:   Fri, 15 Dec 2017 10:45:15 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Stephen Bates <sbates@...thlin.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Daniel Mentz <danielmentz@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will.deacon@....com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 077/105] lib/genalloc.c: make the avail variable an atomic_long_t

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

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


[ Upstream commit 36a3d1dd4e16bcd0d2ddfb4a2ec7092f0ae0d931 ]

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.  This is only expected to be an issue on
64 bit systems.

Add the <linux/atomic.h> header to pull in atomic_long* operations.  So
that 32 bit systems continue to use atomic32_t but 64 bit systems can
use atomic64_t.

Link: http://lkml.kernel.org/r/1509033843-25667-1-git-send-email-sbates@raithlin.com
Signed-off-by: Stephen Bates <sbates@...thlin.com>
Reviewed-by: Logan Gunthorpe <logang@...tatee.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Reviewed-by: Daniel Mentz <danielmentz@...gle.com>
Cc: Jonathan Corbet <corbet@....net>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Will Deacon <will.deacon@....com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/linux/genalloc.h |    3 ++-
 lib/genalloc.c           |   10 +++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -31,6 +31,7 @@
 #define __GENALLOC_H__
 
 #include <linux/spinlock_types.h>
+#include <linux/atomic.h>
 
 struct device;
 struct device_node;
@@ -68,7 +69,7 @@ struct gen_pool {
  */
 struct gen_pool_chunk {
 	struct list_head next_chunk;	/* next chunk in pool */
-	atomic_t avail;
+	atomic_long_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) */
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -194,7 +194,7 @@ int gen_pool_add_virt(struct gen_pool *p
 	chunk->phys_addr = phys;
 	chunk->start_addr = virt;
 	chunk->end_addr = virt + size - 1;
-	atomic_set(&chunk->avail, size);
+	atomic_long_set(&chunk->avail, size);
 
 	spin_lock(&pool->lock);
 	list_add_rcu(&chunk->next_chunk, &pool->chunks);
@@ -285,7 +285,7 @@ unsigned long gen_pool_alloc(struct gen_
 	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 > atomic_long_read(&chunk->avail))
 			continue;
 
 		start_bit = 0;
@@ -305,7 +305,7 @@ retry:
 
 		addr = chunk->start_addr + ((unsigned long)start_bit << order);
 		size = nbits << order;
-		atomic_sub(size, &chunk->avail);
+		atomic_long_sub(size, &chunk->avail);
 		break;
 	}
 	rcu_read_unlock();
@@ -371,7 +371,7 @@ void gen_pool_free(struct gen_pool *pool
 			remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 			BUG_ON(remain);
 			size = nbits << order;
-			atomic_add(size, &chunk->avail);
+			atomic_long_add(size, &chunk->avail);
 			rcu_read_unlock();
 			return;
 		}
@@ -445,7 +445,7 @@ size_t gen_pool_avail(struct gen_pool *p
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
-		avail += atomic_read(&chunk->avail);
+		avail += atomic_long_read(&chunk->avail);
 	rcu_read_unlock();
 	return avail;
 }