* [PATCH] scsi: target: iscsi: Drop unnecessary container_of
@ 2021-05-10 4:08 Guenter Roeck
2021-05-15 2:42 ` Martin K. Petersen
0 siblings, 1 reply; 2+ messages in thread
From: Guenter Roeck @ 2021-05-10 4:08 UTC (permalink / raw)
To: Martin K . Petersen
Cc: linux-scsi, target-devel, linux-kernel, Guenter Roeck, Hou Pu,
Mike Christie
The structure pointer passed to container_of() is never NULL; that was
already checked. That means that the result of container_of() operations
on it is also never NULL, even though se_node_acl is the first element
of the structure embedding it. On top of that, it is misleading to perform
a NULL check on the result of container_of() because the position of the
contained element could change, which would make the test invalid.
Remove the unnecessary NULL check.
As it turns out, the container_of operation was only made for the purpose
of the NULL check. If the container_of is actually needed, it is repeated
later. Remove the container_of operation as well.
The NULL check was identified and removed with the following Coccinelle
script.
@@
type t;
identifier v;
statement s;
@@
<+...
(
t v = container_of(...);
|
v = container_of(...);
)
...
when != v
- if (\( !v \| v == NULL \) ) s
...+>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Hou Pu <houpu@bytedance.com>
Cc: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
drivers/target/iscsi/iscsi_target_nego.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index 151e2949bb75..fb1b5816a5b6 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -118,13 +118,6 @@ static u32 iscsi_handle_authentication(
" CHAP auth\n");
return -1;
}
- iscsi_nacl = container_of(se_nacl, struct iscsi_node_acl,
- se_node_acl);
- if (!iscsi_nacl) {
- pr_err("Unable to locate struct iscsi_node_acl for"
- " CHAP auth\n");
- return -1;
- }
if (se_nacl->dynamic_node_acl) {
iscsi_tpg = container_of(se_nacl->se_tpg,
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] scsi: target: iscsi: Drop unnecessary container_of
2021-05-10 4:08 [PATCH] scsi: target: iscsi: Drop unnecessary container_of Guenter Roeck
@ 2021-05-15 2:42 ` Martin K. Petersen
0 siblings, 0 replies; 2+ messages in thread
From: Martin K. Petersen @ 2021-05-15 2:42 UTC (permalink / raw)
To: Guenter Roeck
Cc: Martin K . Petersen, linux-scsi, target-devel, linux-kernel,
Hou Pu, Mike Christie
Guenter,
> The structure pointer passed to container_of() is never NULL; that was
> already checked. That means that the result of container_of()
> operations on it is also never NULL, even though se_node_acl is the
> first element of the structure embedding it. On top of that, it is
> misleading to perform a NULL check on the result of container_of()
> because the position of the contained element could change, which
> would make the test invalid. Remove the unnecessary NULL check.
Applied to 5.14/scsi-staging, thanks!
--
Martin K. Petersen Oracle Linux Engineering
^ permalink raw reply [flat|nested] 2+ messages in thread
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