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Date:   Tue, 31 May 2022 14:17:44 -0400
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Subject: [PATCH 04/10] dmapool: improve accuracy of debug statistics
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From:   Tony Battersby <tonyb@cybernetics.com>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc:     iommu@lists.linux-foundation.org, kernel-team@fb.com,
        Matthew Wilcox <willy@infradead.org>,
        Keith Busch <kbusch@kernel.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Tony Lindgren <tony@atomide.com>
References: <9b08ab7c-b80b-527d-9adf-7716b0868fbc@cybernetics.com>
In-Reply-To: <9b08ab7c-b80b-527d-9adf-7716b0868fbc@cybernetics.com>
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Precedence: bulk

The "total number of blocks in pool" debug statistic currently does not
take the boundary value into account, so it diverges from the "total
number of blocks in use" statistic when a boundary is in effect.  Add a
calculation for the number of blocks per allocation that takes the
boundary into account, and use it to replace the inaccurate calculation.

This depends on the patch "dmapool: fix boundary comparison" for the
calculated blks_per_alloc value to be correct.

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
---
 mm/dmapool.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/dmapool.c b/mm/dmapool.c
index 782143144a32..9e30f4425dea 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -47,6 +47,7 @@ struct dma_pool {		/* the pool */
 	struct device *dev;
 	unsigned int allocation;
 	unsigned int boundary;
+	unsigned int blks_per_alloc;
 	char name[32];
 	struct list_head pools;
 };
@@ -92,8 +93,7 @@ static ssize_t pools_show(struct device *dev, struct device_attribute *attr, cha
 		/* per-pool info, no real statistics yet */
 		temp = scnprintf(next, size, "%-16s %4zu %4zu %4u %2u\n",
 				 pool->name, blocks,
-				 (size_t) pages *
-				 (pool->allocation / pool->size),
+				 (size_t) pages * pool->blks_per_alloc,
 				 pool->size, pages);
 		size -= temp;
 		next += temp;
@@ -168,6 +168,9 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 	retval->size = size;
 	retval->boundary = boundary;
 	retval->allocation = allocation;
+	retval->blks_per_alloc =
+		(allocation / boundary) * (boundary / size) +
+		(allocation % boundary) / size;
 
 	INIT_LIST_HEAD(&retval->pools);
 
-- 
2.25.1