From 9eb447bb0ed08ec749581df90878a994f7a31e28 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Mon, 28 Oct 2019 14:56:46 -0700
Subject: [PATCH] dma-debug: add a schedule point in debug_dma_dump_mappings()

BugLink: https://bugs.launchpad.net/bugs/1860602

[ Upstream commit 9ff6aa027dbb98755f0265695354f2dd07c0d1ce ]

debug_dma_dump_mappings() can take a lot of cpu cycles :

lpk43:/# time wc -l /sys/kernel/debug/dma-api/dump
163435 /sys/kernel/debug/dma-api/dump

real	0m0.463s
user	0m0.003s
sys	0m0.459s

Let's add a cond_resched() to avoid holding cpu for too long.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Corentin Labbe <clabbe@baylibre.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
---
 lib/dma-debug.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 1b34d210452c..35f843d11230 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -437,6 +437,7 @@ void debug_dma_dump_mappings(struct device *dev)
 		}
 
 		spin_unlock_irqrestore(&bucket->lock, flags);
+		cond_resched();
 	}
 }
 EXPORT_SYMBOL(debug_dma_dump_mappings);
-- 
2.39.2