Patch "dma-debug: add a schedule point in debug_dma_dump_mappings()" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dma-debug-add-a-schedule-point-in-debug_dma_dump_map.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ee27a3bca48b093a1012e9d4d3bc5cf0da43364b
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date:   Mon Oct 28 14:56:46 2019 -0700

    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@xxxxxxxxxx>
    Cc: Corentin Labbe <clabbe@xxxxxxxxxxxx>
    Cc: Christoph Hellwig <hch@xxxxxx>
    Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
    Signed-off-by: Christoph Hellwig <hch@xxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index c007d25bee09..3a2397444076 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();
 	}
 }