The patch titled
Subject: dma-debug: fix locking bug in check_unmap()
has been added to the -mm tree. Its filename is
dma-debug-fix-locking-bug-in-check_unmap.patch
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From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
Subject: dma-debug: fix locking bug in check_unmap()
In check_unmap() it is possible to get into a dead-locked state if
dma_mapping_error is called. The problem is that the bucket is locked in
check_unmap, and locked again by debug_dma_mapping_error which is called
by dma_mapping_error. To resolve that we must release the lock on the
bucket before making the call to dma_mapping_error.
Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Shuah Khan <shuah.khan@xxxxxx>
Cc: Jakub Kicinski <kubakici@xxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/dma-debug.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff -puN lib/dma-debug.c~dma-debug-fix-locking-bug-in-check_unmap lib/dma-debug.c
--- a/lib/dma-debug.c~dma-debug-fix-locking-bug-in-check_unmap
+++ a/lib/dma-debug.c
@@ -862,17 +862,18 @@ static void check_unmap(struct dma_debug
entry = bucket_find_exact(bucket, ref);
if (!entry) {
+ /* must drop lock before calling dma_mapping_error */
+ put_hash_bucket(bucket, &flags);
+
if (dma_mapping_error(ref->dev, ref->dev_addr)) {
err_printk(ref->dev, NULL,
- "DMA-API: device driver tries "
- "to free an invalid DMA memory address\n");
- return;
+ "DMA-API: device driver tries to free an invalid DMA memory address\n");
+ } else {
+ err_printk(ref->dev, NULL,
+ "DMA-API: device driver tries to free DMA memory it has not allocated [device address=0x%016llx] [size=%llu bytes]\n",
+ ref->dev_addr, ref->size);
}
- err_printk(ref->dev, NULL, "DMA-API: device driver tries "
- "to free DMA memory it has not allocated "
- "[device address=0x%016llx] [size=%llu bytes]\n",
- ref->dev_addr, ref->size);
- goto out;
+ return;
}
if (ref->size != entry->size) {
@@ -936,7 +937,6 @@ static void check_unmap(struct dma_debug
hash_bucket_del(entry);
dma_entry_free(entry);
-out:
put_hash_bucket(bucket, &flags);
}
_
Patches currently in -mm which might be from alexander.h.duyck@xxxxxxxxx are
linux-next.patch
dma-debug-fix-locking-bug-in-check_unmap.patch
dma-debug-fix-locking-bug-in-check_unmap-fix.patch
dma-debug-update-dma-debug-api-to-better-handle-multiple-mappings-of-a-buffer.patch
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