lib/dma-debug.c: fix __hash_bucket_find()

If there is only one match, the unique matched entry should be returned.

Without the fix, the upcoming dma debug interfaces ("dma-debug: new
interfaces to debug dma mapping errors") can't work reliably because
only device and dma_addr are passed to dma_mapping_error().

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Tested-by: Shuah Khan <shuah.khan@hp.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index b9087bf..d84beb9 100644 (file)
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -264,7 +264,7 @@ static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
                                                  match_fn match)
 {
        struct dma_debug_entry *entry, *ret = NULL;
-       int matches = 0, match_lvl, last_lvl = 0;
+       int matches = 0, match_lvl, last_lvl = -1;
 
        list_for_each_entry(entry, &bucket->list, list) {
                if (!match(ref, entry))
@@ -293,7 +293,7 @@ static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
                } else if (match_lvl > last_lvl) {
                        /*
                         * We found an entry that fits better then the
-                        * previous one
+                        * previous one or it is the 1st match.
                         */
                        last_lvl = match_lvl;
                        ret      = entry;