netdev - Calling nlmsg_multicast and nlmsg_new in softirq context, netfilter hook function

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Message-ID: <CABTgHBvx62nrr2fSOFFyDaB7OUpOJ-uozOg7_Y0adbLJxJhZcA@mail.gmail.com>
Date: Wed, 9 Aug 2023 20:02:53 +0530
From: Nayan Gadre <beejoy.nayan@...il.com>
To: netdev@...r.kernel.org
Subject: Calling nlmsg_multicast and nlmsg_new in softirq context, netfilter
 hook function

Hi,

I have a netfilter hook attached at NF_NETDEV_INGRESS, very early in
the network stack. I am doing some filtering on the sk_buff and if it
matches a certain condition, I want to send a netlink event to an
application.

This will involve allocating a buffer to send using nlmsg_new, with
GFP_ATOMIC flag, as the hook will run in the bottom half and then call
nlmsg_multicast().

Is it safe to call these APIs in the softirq context / netfilter hook function?

Thanks
N Gadre.