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Message-ID: <1786d5aa-2474-4bd3-92ee-c5a880a37728@linux.ibm.com>
Date: Mon, 17 Jun 2024 19:23:45 +0530
From: Sourabh Jain <sourabhjain@...ux.ibm.com>
To: Jeff Layton <jlayton@...nel.org>, Chuck Lever <chuck.lever@...cle.com>,
Neil Brown <neilb@...e.de>, Olga Kornievskaia <kolga@...app.com>,
Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>
Cc: Trond Myklebust <trond.myklebust@...merspace.com>,
Anna Schumaker <anna@...nel.org>, linux-nfs@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfsd: fix oops when reading pool_stats before server is
started
Hello Jeff,
With the below fix applied, the issue is not observed.
Tested-by: Sourabh Jain <sourabhjain@...ux.ibm.com>
Thanks for the fix.
- Sourabh Jain
On 17/06/24 17:24, Jeff Layton wrote:
> Sourbh reported an oops that is triggerable by trying to read the
> pool_stats procfile before nfsd had been started. Move the check for a
> NULL serv in svc_pool_stats_start above the mutex acquisition, and fix
> the stop routine not to unlock the mutex if there is no serv yet.
>
> Fixes: 7b207ccd9833 ("svc: don't hold reference for poolstats, only mutex.")
> Reported-by: Sourabh Jain <sourabhjain@...ux.ibm.com>
> Signed-off-by: Jeff Layton <jlayton@...nel.org>
> ---
> net/sunrpc/svc_xprt.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index d3735ab3e6d1..b757a8891813 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -1422,12 +1422,13 @@ static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos)
>
> dprintk("svc_pool_stats_start, *pidx=%u\n", pidx);
>
> + if (!si->serv)
> + return NULL;
> +
> mutex_lock(si->mutex);
>
> if (!pidx)
> return SEQ_START_TOKEN;
> - if (!si->serv)
> - return NULL;
> return pidx > si->serv->sv_nrpools ? NULL
> : &si->serv->sv_pools[pidx - 1];
> }
> @@ -1459,7 +1460,8 @@ static void svc_pool_stats_stop(struct seq_file *m, void *p)
> {
> struct svc_info *si = m->private;
>
> - mutex_unlock(si->mutex);
> + if (si->serv)
> + mutex_unlock(si->mutex);
> }
>
> static int svc_pool_stats_show(struct seq_file *m, void *p)
>
> ---
> base-commit: 4ddfda417a50309f17aeb85f8d1a9a9efbc7d81c
> change-id: 20240617-nfsd-next-8593f73544f5
>
> Best regards,
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