From: Eric Dumazet <edumazet@google.com>
Date: Mon, 28 Oct 2019 21:56:46 +0000 (-0700)
Subject: dma-debug: add a schedule point in debug_dma_dump_mappings()
X-Git-Tag: v4.19.93~97
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ea44828c4106ec6acb441474f1a99ac5d3911efe;p=thirdparty%2Fkernel%2Fstable.git

dma-debug: add a schedule point in debug_dma_dump_mappings()

[ 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>
---

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index c007d25bee098..3a2397444076e 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -442,6 +442,7 @@ void debug_dma_dump_mappings(struct device *dev)
 		}
 
 		spin_unlock_irqrestore(&bucket->lock, flags);
+		cond_resched();
 	}
 }