Re: [PATCH AUTOSEL 5.1 004/375] NFS: make nfs_match_client killable

[Benjamin Coddington]

Hi Sasha,  if you take this one, you'll need the fix for it:

c260121a97a3 ("NFS: Fix a double unlock from nfs_match,get_client")

I didn't see this fix go through my inbox for your stable tree, so 
apologies if maybe I missed it.

Looks like you are also applying this one to 4.19 and 4.14, -- I'll just 
reply once here.

Ben

On 22 May 2019, at 15:15, Sasha Levin wrote:

> From: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx>
>
> [ Upstream commit 950a578c6128c2886e295b9c7ecb0b6b22fcc92b ]
>
>     Actually we don't do anything with return value from
>     nfs_wait_client_init_complete in nfs_match_client, as a
>     consequence if we get a fatal signal and client is not
>     fully initialised, we'll loop to "again" label
>
>     This has been proven to cause soft lockups on some scenarios
>     (no-carrier but configured network interfaces)
>
> Signed-off-by: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx>
> Reviewed-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
> Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  fs/nfs/client.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 90d71fda65cec..350cfa561e0e8 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -284,6 +284,7 @@ static struct nfs_client *nfs_match_client(const 
> struct nfs_client_initdata *dat
>  	struct nfs_client *clp;
>  	const struct sockaddr *sap = data->addr;
>  	struct nfs_net *nn = net_generic(data->net, nfs_net_id);
> +	int error;
>
>  again:
>  	list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
> @@ -296,8 +297,10 @@ static struct nfs_client *nfs_match_client(const 
> struct nfs_client_initdata *dat
>  		if (clp->cl_cons_state > NFS_CS_READY) {
>  			refcount_inc(&clp->cl_count);
>  			spin_unlock(&nn->nfs_client_lock);
> -			nfs_wait_client_init_complete(clp);
> +			error = nfs_wait_client_init_complete(clp);
>  			nfs_put_client(clp);
> +			if (error < 0)
> +				return ERR_PTR(error);
>  			spin_lock(&nn->nfs_client_lock);
>  			goto again;
>  		}
> @@ -407,6 +410,8 @@ struct nfs_client *nfs_get_client(const struct 
> nfs_client_initdata *cl_init)
>  		clp = nfs_match_client(cl_init);
>  		if (clp) {
>  			spin_unlock(&nn->nfs_client_lock);
> +			if (IS_ERR(clp))
> +				return clp;
>  			if (new)
>  				new->rpc_ops->free_client(new);
>  			return nfs_found_client(cl_init, clp);
> --
> 2.20.1