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

* [PATCH] dma-debug: add a schedule point in debug_dma_dump_mappings()
@ 2019-10-28 21:56 Eric Dumazet
  2019-10-30 18:12 ` Christoph Hellwig
  0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2019-10-28 21:56 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: linux-kernel, Eric Dumazet, Eric Dumazet, Corentin Labbe,
	Marek Szyprowski

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

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 099002d84f466af0a8e421d035ac8eb119e08bd8..4ad74f5987ea9e95f9bb5e2d1592254e367d24fb 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();
 	}
 }
 
-- 
2.24.0.rc0.303.g954a862665-goog


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