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From: Trond Myklebust <trondmy@hammerspace.com>
To: "chuck.lever@oracle.com" <chuck.lever@oracle.com>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
Subject: Re: [PATCH v3 07/26] xprtrdma: Improve locking around rpcrdma_rep destruction
Date: Fri, 23 Apr 2021 21:06:28 +0000
Message-ID: <89d2e2bbc40d953e28c4e4d56be0b5c83c25dc23.camel@hammerspace.com> (raw)
In-Reply-To: <161885534259.38598.17355600080366820390.stgit@manet.1015granger.net>

On Mon, 2021-04-19 at 14:02 -0400, Chuck Lever wrote:
> Currently rpcrdma_reps_destroy() assumes that, at transport
> tear-down, the content of the rb_free_reps list is the same as the
> content of the rb_all_reps list. Although that is usually true,
> using the rb_all_reps list should be more reliable because of
> the way it's managed. And, rpcrdma_reps_unmap() uses rb_all_reps;
> these two functions should both traverse the "all" list.
> 
> Ensure that all rpcrdma_reps are always destroyed whether they are
> on the rep free list or not.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  net/sunrpc/xprtrdma/verbs.c |   31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/verbs.c
> b/net/sunrpc/xprtrdma/verbs.c
> index 1b599a623eea..482fdc9e25c2 100644
> --- a/net/sunrpc/xprtrdma/verbs.c
> +++ b/net/sunrpc/xprtrdma/verbs.c
> @@ -1007,16 +1007,23 @@ struct rpcrdma_rep *rpcrdma_rep_create(struct
> rpcrdma_xprt *r_xprt,
>         return NULL;
>  }
>  
> -/* No locking needed here. This function is invoked only by the
> - * Receive completion handler, or during transport shutdown.
> - */
> -static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep)
> +static void rpcrdma_rep_destroy_locked(struct rpcrdma_rep *rep)

The name here is extremely confusing. As far as I can tell, this isn't
called with any lock?

>  {
> -       list_del(&rep->rr_all);
>         rpcrdma_regbuf_free(rep->rr_rdmabuf);
>         kfree(rep);
>  }
>  
> +static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep)
> +{
> +       struct rpcrdma_buffer *buf = &rep->rr_rxprt->rx_buf;
> +
> +       spin_lock(&buf->rb_lock);
> +       list_del(&rep->rr_all);
> +       spin_unlock(&buf->rb_lock);
> +
> +       rpcrdma_rep_destroy_locked(rep);
> +}
> +
>  static struct rpcrdma_rep *rpcrdma_rep_get_locked(struct
> rpcrdma_buffer *buf)
>  {
>         struct llist_node *node;
> @@ -1049,8 +1056,18 @@ static void rpcrdma_reps_destroy(struct
> rpcrdma_buffer *buf)
>  {
>         struct rpcrdma_rep *rep;
>  
> -       while ((rep = rpcrdma_rep_get_locked(buf)) != NULL)
> -               rpcrdma_rep_destroy(rep);
> +       spin_lock(&buf->rb_lock);
> +       while ((rep = list_first_entry_or_null(&buf->rb_all_reps,
> +                                              struct rpcrdma_rep,
> +                                              rr_all)) != NULL) {
> +               list_del(&rep->rr_all);
> +               spin_unlock(&buf->rb_lock);
> +
> +               rpcrdma_rep_destroy_locked(rep);
> +
> +               spin_lock(&buf->rb_lock);
> +       }
> +       spin_unlock(&buf->rb_lock);
>  }
>  
>  /**
> 
> 

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com



  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19 18:01 [PATCH v3 00/26] NFS/RDMA client patches for next Chuck Lever
2021-04-19 18:01 ` [PATCH v3 01/26] SUNRPC: Move fault injection call sites Chuck Lever
2021-04-19 18:05   ` Chuck Lever III
2021-04-19 18:01 ` [PATCH v3 02/26] SUNRPC: Remove trace_xprt_transmit_queued Chuck Lever
2021-04-19 18:01 ` [PATCH v3 03/26] SUNRPC: Add tracepoint that fires when an RPC is retransmitted Chuck Lever
2021-04-19 18:02 ` [PATCH v3 04/26] xprtrdma: Avoid Receive Queue wrapping Chuck Lever
2021-04-19 18:02 ` [PATCH v3 05/26] xprtrdma: Do not refresh Receive Queue while it is draining Chuck Lever
2021-04-19 18:02 ` [PATCH v3 06/26] xprtrdma: Put flushed Receives on free list instead of destroying them Chuck Lever
2021-04-19 18:02 ` [PATCH v3 07/26] xprtrdma: Improve locking around rpcrdma_rep destruction Chuck Lever
2021-04-23 21:06   ` Trond Myklebust [this message]
2021-04-24 17:39     ` Chuck Lever III
2021-04-24 17:59       ` Trond Myklebust
2021-04-19 18:02 ` [PATCH v3 08/26] xprtrdma: Improve commentary around rpcrdma_reps_unmap() Chuck Lever
2021-04-19 18:02 ` [PATCH v3 09/26] xprtrdma: Improve locking around rpcrdma_rep creation Chuck Lever
2021-04-19 18:02 ` [PATCH v3 10/26] xprtrdma: Fix cwnd update ordering Chuck Lever
2021-04-19 18:02 ` [PATCH v3 11/26] xprtrdma: Delete rpcrdma_recv_buffer_put() Chuck Lever
2021-04-19 18:02 ` [PATCH v3 12/26] xprtrdma: rpcrdma_mr_pop() already does list_del_init() Chuck Lever
2021-04-19 18:03 ` [PATCH v3 13/26] xprtrdma: Rename frwr_release_mr() Chuck Lever
2021-04-19 18:03 ` [PATCH v3 14/26] xprtrdma: Clarify use of barrier in frwr_wc_localinv_done() Chuck Lever
2021-04-19 18:03 ` [PATCH v3 15/26] xprtrdma: Do not recycle MR after FastReg/LocalInv flushes Chuck Lever
2021-04-25 14:19   ` Dan Aloni
2021-04-25 16:21     ` Chuck Lever III
2021-04-25 17:00       ` Dan Aloni
2021-04-19 18:03 ` [PATCH v3 16/26] xprtrdma: Do not wake RPC consumer on a failed LocalInv Chuck Lever
2021-04-19 18:03 ` [PATCH v3 17/26] xprtrdma: Avoid Send Queue wrapping Chuck Lever
2021-04-19 18:03 ` [PATCH v3 18/26] xprtrdma: Add tracepoints showing FastReg WRs and remote invalidation Chuck Lever
2021-04-19 18:03 ` [PATCH v3 19/26] xprtrdma: Add an rpcrdma_mr_completion_class Chuck Lever
2021-04-19 18:03 ` [PATCH v3 20/26] xprtrdma: Don't display r_xprt memory addresses in tracepoints Chuck Lever
2021-04-19 18:03 ` [PATCH v3 21/26] xprtrdma: Remove the RPC/RDMA QP event handler Chuck Lever
2021-04-19 18:03 ` [PATCH v3 22/26] xprtrdma: Move fr_cid to struct rpcrdma_mr Chuck Lever
2021-04-19 18:04 ` [PATCH v3 23/26] xprtrdma: Move cqe " Chuck Lever
2021-04-19 18:04 ` [PATCH v3 24/26] xprtrdma: Move fr_linv_done field " Chuck Lever
2021-04-19 18:04 ` [PATCH v3 25/26] xprtrdma: Move the Work Request union " Chuck Lever
2021-04-19 18:04 ` [PATCH v3 26/26] xprtrdma: Move fr_mr field " Chuck Lever

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