scsi: lib/sg_pool.c: clear 'first_chunk' in case of no preallocation

If user doesn't ask to preallocate by passing zero 'nents_first_chunk' to sg_alloc_table_chained, we need to make sure that 'first_chunk' is cleared. Otherwise, __sg_alloc_table() still may think that the 1st SGL should be from the preallocation. Fixes the issue by clearing 'first_chunk' in sg_alloc_table_chained() if 'nents_first_chunk' is zero. Cc: Christoph Hellwig <[email protected]> Cc: Bart Van Assche <[email protected]> Cc: Ewan D. Milne <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: Guenter Roeck <[email protected]> Reported-by: Guenter Roeck <[email protected]> Tested-by: Guenter Roeck <[email protected]> Signed-off-by: Ming Lei <[email protected]> Signed-off-by: Martin K. Petersen <[email protected]>
govindsi · Jun 20, 2019 · b79d9a0 · b79d9a0
1 parent 3dccdf5
commit b79d9a0
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/lib/sg_pool.c b/lib/sg_pool.c
@@ -102,7 +102,9 @@ EXPORT_SYMBOL_GPL(sg_free_table_chained);
  *
  *  Description:
  *    Allocate and chain SGLs in an sg table. If @nents@ is larger than
- *    @nents_first_chunk a chained sg table will be setup.
+ *    @nents_first_chunk a chained sg table will be setup. @first_chunk is
+ *    ignored if nents_first_chunk <= 1 because user expects the SGL points
+ *    non-chain SGL.
  *
  **/
 int sg_alloc_table_chained(struct sg_table *table, int nents,
@@ -121,7 +123,7 @@ int sg_alloc_table_chained(struct sg_table *table, int nents,
 	}
 
 	/* User supposes that the 1st SGL includes real entry */
-	if (nents_first_chunk == 1) {
+	if (nents_first_chunk <= 1) {
 		first_chunk = NULL;
 		nents_first_chunk = 0;
 	}