Re: [PATCH] netfilter: nf_ct_helper: Fix possible panic when nf_conntrack_helper_unregister is used in an unloadable module

[Sergei Shtylyov]

Hello!

On 01.03.2019 8:56, Su Yanjun wrote:

> From: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx>
>
> Because nf_conntrack_helper_unregister maybe used in an unloadable module,
> it uses 'synchronize_rcu' which may cause kernel panic.
>
> According to the artical:

   Article?

> RCU and Unloadable Modules
> https://lwn.net/Articles/217484/
>
> When we have a heavy rcu callback load, then some of the callbacks might be
> deferred in order to allow other processing to proceed. sychnorize_rcu does
> not wait rcu callback complete and module may be unloaded before callback
> done.
>
> This patch uses rcu_barrier instead of synchronize_rcu will prevent this
                                                        ^ that/which missed?

> situation.
>
> Signed-off-by: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx>
[...]

MBR, Sergei