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Subject: Re: [for-6.11 PATCH 04/29] sunrpc: handle NULL req->defer in
 cache_defer_req
From: Jeff Layton <jlayton@kernel.org>
To: Mike Snitzer <snitzer@kernel.org>, linux-nfs@vger.kernel.org
Cc: Chuck Lever <chuck.lever@oracle.com>, Trond Myklebust
	 <trondmy@hammerspace.com>, snitzer@hammerspace.com, neilb@suse.de
Date: Mon, 10 Jun 2024 08:21:40 -0400
In-Reply-To: <20240607142646.20924-5-snitzer@kernel.org>
References: <20240607142646.20924-1-snitzer@kernel.org>
	 <20240607142646.20924-5-snitzer@kernel.org>
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On Fri, 2024-06-07 at 10:26 -0400, Mike Snitzer wrote:
> From: Weston Andros Adamson <dros@primarydata.com>
>=20
> Dont crash with a NULL pointer dereference when req->defer isn't
> set. This is needed for the localio path.
>=20
> Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
> Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
> ---
> =C2=A0net/sunrpc/cache.c | 2 ++
> =C2=A01 file changed, 2 insertions(+)
>=20
> diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
> index 95ff74706104..b757b891382c 100644
> --- a/net/sunrpc/cache.c
> +++ b/net/sunrpc/cache.c
> @@ -714,6 +714,8 @@ static bool cache_defer_req(struct cache_req
> *req, struct cache_head *item)
> =C2=A0			return false;
> =C2=A0	}
> =C2=A0
> +	if (!req->defer)
> +		return false;
> =C2=A0	dreq =3D req->defer(req);
> =C2=A0	if (dreq =3D=3D NULL)
> =C2=A0		return false;

I've gone over it many times, but I still don't quite "get" the
deferral handling code. I think the above is probably safe, but please
do Cc Neil Brown on later postings of this series since he has a better
grasp of that code.
--=20
Jeff Layton <jlayton@kernel.org>