On Tue, Feb 12, 2013 at 12:33:15PM -0700, Tim Gardner wrote:
> Even though nlmclnt_reclaim() is only one call into the stack frame,
> 928 bytes on the stack seems like a lot. Recode to dynamically
> allocate the request structure once from within the reclaimer task,
> then pass this pointer into nlmclnt_reclaim() for reuse on
> subsequent calls.
>
> smatch analysis:
>
> fs/lockd/clntproc.c:620 nlmclnt_reclaim() warn: 'reqst' puts
> 928 bytes on stack
>
> Also remove redundant assignment of 0 after memset.
>
> Cc: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
> Cc: linux-nfs@xxxxxxxxxxxxxxx
> Signed-off-by: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>
> ---
> fs/lockd/clntlock.c | 8 +++++++-
> fs/lockd/clntproc.c | 6 ++----
> include/linux/lockd/lockd.h | 3 ++-
> 3 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
> index 4885b53..5dd23ef 100644
> --- a/fs/lockd/clntlock.c
> +++ b/fs/lockd/clntlock.c
> @@ -220,10 +220,15 @@ reclaimer(void *ptr)
> {
> struct nlm_host *host = (struct nlm_host *) ptr;
> struct nlm_wait *block;
> + struct nlm_rqst *req;
> struct file_lock *fl, *next;
> u32 nsmstate;
> struct net *net = host->net;
>
> + req = kmalloc(sizeof(*req), GFP_KERNEL);
> + if (!req)
> + return -ENOMEM;
> +
It caught my eye that this function has never actually returned anything
but 0 before....
But OK I don't think there's a problem there: it could already fail to
reclaim individual locks due to allocation or other failures, and could
fail to run entirely if kthread_run failed.
But maybe we should log the same "Locks for %s won't be reclaimed!"
error in this case that we would in the case the kthread_run() in
nlmclnt_recovery fails.
--b.
> allow_signal(SIGKILL);
>
> down_write(&host->h_rwsem);
> @@ -253,7 +258,7 @@ restart:
> */
> if (signalled())
> continue;
> - if (nlmclnt_reclaim(host, fl) != 0)
> + if (nlmclnt_reclaim(host, fl, req) != 0)
> continue;
> list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
> if (host->h_nsmstate != nsmstate) {
> @@ -279,5 +284,6 @@ restart:
> /* Release host handle after use */
> nlmclnt_release_host(host);
> lockd_down(net);
> + kfree(req);
> return 0;
> }
> diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
> index 54f9e6c..b43114c 100644
> --- a/fs/lockd/clntproc.c
> +++ b/fs/lockd/clntproc.c
> @@ -615,17 +615,15 @@ out_unlock:
> * RECLAIM: Try to reclaim a lock
> */
> int
> -nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
> +nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
> + struct nlm_rqst *req)
> {
> - struct nlm_rqst reqst, *req;
> int status;
>
> - req = &reqst;
> memset(req, 0, sizeof(*req));
> locks_init_lock(&req->a_args.lock.fl);
> locks_init_lock(&req->a_res.lock.fl);
> req->a_host = host;
> - req->a_flags = 0;
>
> /* Set up the argument struct */
> nlmclnt_setlockargs(req, fl);
> diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
> index f5a051a..a395f1e 100644
> --- a/include/linux/lockd/lockd.h
> +++ b/include/linux/lockd/lockd.h
> @@ -212,7 +212,8 @@ int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
> __be32 nlmclnt_grant(const struct sockaddr *addr,
> const struct nlm_lock *lock);
> void nlmclnt_recovery(struct nlm_host *);
> -int nlmclnt_reclaim(struct nlm_host *, struct file_lock *);
> +int nlmclnt_reclaim(struct nlm_host *, struct file_lock *,
> + struct nlm_rqst *);
> void nlmclnt_next_cookie(struct nlm_cookie *);
>
> /*
> --
> 1.7.9.5
>
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