Hello Jay,
On Tue, Sep 09, 2025 at 05:18:26PM -0700, Jay Vosburgh wrote:
> Second, I'm a bit unsure what's going on with the struct netpoll
> *np parameter of __netpoll_setup for the second and subsequent netpoll
> instances (i.e., second and later call), as the function will
> unconditionally do
>
> npinfo->netpoll = np;
>
> which it seems like would overwrite the "np" supplied by any
> prior calls to __netpoll_setup.
This is clearly a bug. Trying to understand where this field is used, it
seems it is not used at all.
I was not able to find any usage of it, and removing it and compiling
with `allyesconfig` didn't complain about any other users also.
I think we should remove it.
commit 5da5611575ce94ca557c194d4147ae3011cedb6f
Author: Breno Leitao <lei...@debian.org>
Date: Wed Sep 10 06:32:25 2025 -0700
netpoll: remove unused netpoll pointer from netpoll_info
The netpoll_info structure contained a useless pointer back to its
associated netpoll. This field is never used, and the assignment in
__netpoll_setup() is does not comtemplate multiple instances, as
reported by Jay[1].
Drop both the member and its initialization to simplify the structure.
Link: https://lore.kernel.org/all/2930648.1757463506@famine/ [1]
Reported-by: Jay Vosburgh <j...@jvosburgh.net>
Signed-off-by: Breno Leitao <lei...@debian.org>
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index b5ea9882eda8b..f22eec4660405 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -55,7 +55,6 @@ struct netpoll_info {
struct delayed_work tx_work;
- struct netpoll *netpoll;
struct rcu_head rcu;
};
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 5f65b62346d4e..c58faa7471650 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -591,7 +591,6 @@ int __netpoll_setup(struct netpoll *np, struct net_device
*ndev)
np->dev = ndev;
strscpy(np->dev_name, ndev->name, IFNAMSIZ);
- npinfo->netpoll = np;
/* fill up the skb queue */
refill_skbs(np);
