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Message-ID: <501e4bf7951c88322c675923ca54ad2b544cae47.camel@kernel.org>
Subject: Re: [PATCH 02/11] nfsd: don't call functions with side-effecting
 inside WARN_ON()
From: Jeff Layton <jlayton@kernel.org>
To: NeilBrown <neilb@suse.de>, Chuck Lever <chuck.lever@oracle.com>
Cc: linux-nfs@vger.kernel.org, Olga Kornievskaia <kolga@netapp.com>, Dai Ngo
	 <Dai.Ngo@oracle.com>, Tom Talpey <tom@talpey.com>
Date: Mon, 27 Nov 2023 08:00:20 -0500
In-Reply-To: <20231124002504.19515-3-neilb@suse.de>
References: <20231124002504.19515-1-neilb@suse.de>
	 <20231124002504.19515-3-neilb@suse.de>
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On Fri, 2023-11-24 at 11:23 +1100, NeilBrown wrote:
> Code like:
>=20
>     WARN_ON(foo())
>=20
> looks like an assertion and might not be expected to have any side
> effects.
> When testing if a function with side-effects fails a construct like
>=20
>     if (foo())
>        WARN_ON(1);
>=20
> makes the intent more obvious.
>=20
> nfsd has several WARN_ON calls where the test has side effects, so it
> would be good to change them.  These cases don't really need the
> WARN_ON.  They have never failed in 8 years of usage so let's just
> remove the WARN_ON wrapper.
>=20
> Suggested-by: Chuck Lever <chuck.lever@oracle.com>
> Signed-off-by: NeilBrown <neilb@suse.de>
> ---
>  fs/nfsd/nfs4state.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>=20
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 042c7a50f425..dd01d0b9e21e 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -1605,7 +1605,7 @@ static void release_open_stateid_locks(struct nfs4_=
ol_stateid *open_stp,
>  	while (!list_empty(&open_stp->st_locks)) {
>  		stp =3D list_entry(open_stp->st_locks.next,
>  				struct nfs4_ol_stateid, st_locks);
> -		WARN_ON(!unhash_lock_stateid(stp));
> +		unhash_lock_stateid(stp);
>  		put_ol_stateid_locked(stp, reaplist);
>  	}
>  }
> @@ -2234,7 +2234,7 @@ __destroy_client(struct nfs4_client *clp)
>  	spin_lock(&state_lock);
>  	while (!list_empty(&clp->cl_delegations)) {
>  		dp =3D list_entry(clp->cl_delegations.next, struct nfs4_delegation, dl=
_perclnt);
> -		WARN_ON(!unhash_delegation_locked(dp));
> +		unhash_delegation_locked(dp);
>  		list_add(&dp->dl_recall_lru, &reaplist);
>  	}
>  	spin_unlock(&state_lock);
> @@ -6234,7 +6234,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>  		dp =3D list_entry (pos, struct nfs4_delegation, dl_recall_lru);
>  		if (!state_expired(&lt, dp->dl_time))
>  			break;
> -		WARN_ON(!unhash_delegation_locked(dp));
> +		unhash_delegation_locked(dp);
>  		list_add(&dp->dl_recall_lru, &reaplist);
>  	}
>  	spin_unlock(&state_lock);
> @@ -8060,7 +8060,7 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
>  		stp =3D list_first_entry(&lo->lo_owner.so_stateids,
>  				       struct nfs4_ol_stateid,
>  				       st_perstateowner);
> -		WARN_ON(!unhash_lock_stateid(stp));
> +		unhash_lock_stateid(stp);
>  		put_ol_stateid_locked(stp, &reaplist);
>  	}
>  	spin_unlock(&clp->cl_lock);
> @@ -8353,7 +8353,7 @@ nfs4_state_shutdown_net(struct net *net)
>  	spin_lock(&state_lock);
>  	list_for_each_safe(pos, next, &nn->del_recall_lru) {
>  		dp =3D list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> -		WARN_ON(!unhash_delegation_locked(dp));
> +		unhash_delegation_locked(dp);
>  		list_add(&dp->dl_recall_lru, &reaplist);
>  	}
>  	spin_unlock(&state_lock);

Reviewed-by: Jeff Layton <jlayton@kernel.org>