[PATCH 4.4 098/137] dma-debug: add a schedule point in debug_dma_dump_mappings()

Greg Kroah-Hartman
2020-01-02T22:41:12Z

From: Eric Dumazet <edumazet@google.com>

[ 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>
---
lib/dma-debug.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 51a76af25c66..173013f5e41b 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -427,6 +427,7 @@ void debug_dma_dump_mappings(struct device *dev)
}

spin_unlock_irqrestore(&bucket->lock, flags);
+ cond_resched();
}
}
EXPORT_SYMBOL(debug_dma_dump_mappings);
--
2.20.1