From: Ming Lei <ming.lei@redhat.com>
Date: Thu, 6 Jun 2019 16:34:08 +0800
Subject: [PATCH] scsi: lib/sg_pool.c: clear 'first_chunk' in case of no
preallocation
Git-commit: b79d9a09ae23c7047bdce3a15e284398334198ea
Patch-Mainline: v5.3-rc1
References: bsc#1141707,bsc#1150973
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 <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
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 b3b8cf62ff49..f1cc8372df67 100644
--- 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;
}
--
2.16.4