Re: [PATCH -next] net/sched: use min() macro instead of doing it manually

[Joe Perches]

On Tue, 2021-12-21 at 10:20 +0000, patchwork-bot+netdevbpf@xxxxxxxxxx
wrote:
> Hello:
> 
> This patch was applied to netdev/net-next.git (master)
> by David S. Miller <davem@xxxxxxxxxxxxx>:
> 
> On Tue, 21 Dec 2021 09:14:55 +0800 you wrote:
> > Fix following coccicheck warnings:
> > ./net/sched/cls_api.c:3333:17-18: WARNING opportunity for min()
> > ./net/sched/cls_api.c:3389:17-18: WARNING opportunity for min()
> > ./net/sched/cls_api.c:3427:17-18: WARNING opportunity for min()
> > 
> > Reported-by: Abaci Robot <abaci@xxxxxxxxxxxxxxxxx>
> > Signed-off-by: Yang Li <yang.lee@xxxxxxxxxxxxxxxxx>
> > 
> > [...]
> 
> Here is the summary with links:
>   - [-next] net/sched: use min() macro instead of doing it manually
>     https://git.kernel.org/netdev/net-next/c/c48c94b0ab75
> 
> You are awesome, thank you!

The patch contained instances like:

---
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
[]
@@ -3333,7 +3333,7 @@ int tc_setup_cb_add(struct tcf_block *block, struct tcf_proto *tp,
 	up_read(&block->cb_lock);
 	if (take_rtnl)
 		rtnl_unlock();
-	return ok_count < 0 ? ok_count : 0;
+	return min(ok_count, 0);
 }
---

I think all of these min uses are somewhat obfuscating and not the
typically used kernel pattern.

If count is negative, it's an error return.

I believe the code would be clearer and more typical if written as:

	if (ok_count < 0)
		return ok_count;

	return 0;
}

The compiler should produce the same object code.