[PATCH] net/sched: taprio: Drop unnecessary NULL check after container_of

[PATCH] net/sched: taprio: Drop unnecessary NULL check after container_of

[Guenter Roeck]

The rcu_head pointer passed to taprio_free_sched_cb is never NULL.
That means that the result of container_of() operations on it is also
never NULL, even though rcu_head 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 check invalid. Remove the
unnecessary NULL check.

This change was made automatically 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
...+>

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 net/sched/sch_taprio.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 5c91df52b8c2..71e8a7a84841 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -114,9 +114,6 @@ static void taprio_free_sched_cb(struct rcu_head *head)
 	struct sched_gate_list *sched = container_of(head, struct sched_gate_list, rcu);
 	struct sched_entry *entry, *n;
 
-	if (!sched)
-		return;
-
 	list_for_each_entry_safe(entry, n, &sched->entries, list) {
 		list_del(&entry->list);
 		kfree(entry);
-- 
2.25.1

Re: [PATCH] net/sched: taprio: Drop unnecessary NULL check after container_of

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Tue, 11 May 2021 13:54:49 -0700 you wrote:
> The rcu_head pointer passed to taprio_free_sched_cb is never NULL.
> That means that the result of container_of() operations on it is also
> never NULL, even though rcu_head 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 check invalid. Remove the
> unnecessary NULL check.
> 
> [...]

Here is the summary with links:
  - net/sched: taprio: Drop unnecessary NULL check after container_of
    https://git.kernel.org/netdev/net-next/c/faa5f5da809b

You are awesome, thank you!
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