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Bruce Fields" Subject: [PATCH v3 3/3] auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 Date: Wed, 12 Jun 2019 20:09:30 +0800 Message-Id: <1560341370-24197-4-git-send-email-wenbinzeng@tencent.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1560341370-24197-1-git-send-email-wenbinzeng@tencent.com> References: <1556692945-3996-1-git-send-email-wenbinzeng@tencent.com> <1560341370-24197-1-git-send-email-wenbinzeng@tencent.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When use-gss-proxy is set to 1, write_gssp() creates a rpc client in gssp_rpc_create(), this increases netns refcount by 2, these refcounts are supposed to be released in rpcsec_gss_exit_net(), but it will never happen because rpcsec_gss_exit_net() is triggered only when netns refcount gets to 0, specifically: refcount=0 -> cleanup_net() -> ops_exit_list -> rpcsec_gss_exit_net It is a deadlock situation here, refcount will never get to 0 unless rpcsec_gss_exit_net() is called. This fix introduced a new callback i.e. evict in struct proc_ns_operations, which is called in nsfs_evict. Moving rpcsec_gss_exit_net to evict path gives it a chance to get called and avoids the above deadlock situation. Signed-off-by: Wenbin Zeng Cc: J. Bruce Fields --- net/sunrpc/auth_gss/auth_gss.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c index 3fd56c0..3e76c8a 100644 --- a/net/sunrpc/auth_gss/auth_gss.c +++ b/net/sunrpc/auth_gss/auth_gss.c @@ -2136,14 +2136,14 @@ static __net_init int rpcsec_gss_init_net(struct net *net) return gss_svc_init_net(net); } -static __net_exit void rpcsec_gss_exit_net(struct net *net) +static void rpcsec_gss_evict_net(struct net *net) { gss_svc_shutdown_net(net); } static struct pernet_operations rpcsec_gss_net_ops = { .init = rpcsec_gss_init_net, - .exit = rpcsec_gss_exit_net, + .evict = rpcsec_gss_evict_net, }; /* -- 1.8.3.1