release/5.2.34/dma-debug-add-a-schedule-point-in-debug_dma_dump_map.patch

From b38fac2557a57c5272fb13c873adb92ff2e15de3 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()

commit 9ff6aa027dbb98755f0265695354f2dd07c0d1ce upstream.

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: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 099002d84f46..4ad74f5987ea 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -420,6 +420,7 @@ void debug_dma_dump_mappings(struct device *dev)
 		}
 
 		spin_unlock_irqrestore(&bucket->lock, flags);
+		cond_resched();
 	}
 }
 
-- 
2.7.4