linux-kernel - [PATCH] dma debug: report -EEXIST errors in add_dma

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Date:   Tue, 18 May 2021 08:54:43 -0400
From:   Hamza Mahfooz <someguy@...ective-light.com>
To:     linux-kernel@...r.kernel.org
Cc:     Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org,
        Hamza Mahfooz <someguy@...ective-light.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH] dma debug: report -EEXIST errors in add_dma_entry

Since, overlapping mappings are not supported by the DMA API we should
report an error if active_cacheline_insert returns -EEXIST.

Suggested-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Hamza Mahfooz <someguy@...ective-light.com>
---
 kernel/dma/debug.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 14de1271463f..dadae6255d05 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -566,11 +566,9 @@ static void add_dma_entry(struct dma_debug_entry *entry)
 	if (rc == -ENOMEM) {
 		pr_err("cacheline tracking ENOMEM, dma-debug disabled\n");
 		global_disable = true;
+	} else if (rc == -EEXIST) {
+		pr_err("cacheline tracking EEXIST, overlapping mappings aren't supported\n");
 	}
-
-	/* TODO: report -EEXIST errors here as overlapping mappings are
-	 * not supported by the DMA API
-	 */
 }
 
 static int dma_debug_create_entries(gfp_t gfp)
-- 
2.31.1