From 8d640a51ec9e9cdefa680b67ad55f933eefc5923 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Fri, 22 Mar 2013 15:04:48 -0700 Subject: [PATCH] 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. [akpm@linux-foundation.org: restore 80-col trickery to be consistent with the rest of the file] Signed-off-by: Alexander Duyck Cc: Joerg Roedel Reviewed-by: Shuah Khan Tested-by: Shuah Khan Cc: Jakub Kicinski Cc: Konrad Rzeszutek Wilk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/dma-debug.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/lib/dma-debug.c b/lib/dma-debug.c index 5e396accd3d..d3e06a5e981 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -862,17 +862,21 @@ static void check_unmap(struct dma_debug_entry *ref) 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 +940,6 @@ static void check_unmap(struct dma_debug_entry *ref) hash_bucket_del(entry); dma_entry_free(entry); -out: put_hash_bucket(bucket, &flags); } -- 2.11.4.GIT