If user doesn't ask to pre-allocate 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 pre-allocation.
Fixes the issue by clearing 'first_chunk' in sg_alloc_table_chained() if
'nents_first_chunk' is zero.
Without this patch, the 2nd one can't work.
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Ewan D. Milne <emilne@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
lib/sg_pool.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/lib/sg_pool.c b/lib/sg_pool.c
index 47eecbe094d8..db29e5c1f790 100644
--- a/lib/sg_pool.c
+++ b/lib/sg_pool.c
@@ -103,7 +103,9 @@ 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,
@@ -122,7 +124,7 @@ 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;
}
--
2.20.1
