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Subject: Re: [PATCH v5 5/9] IB/isert: Replace semaphore sem with completion
To: Binoy Jayan <binoy.jayan@linaro.org>,
        Doug Ledford <dledford@redhat.com>, Sean Hefty <sean.hefty@intel.com>,
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        Ira Weiny <ira.weiny@intel.com>,
        Steve Wise <swise@opengridcomputing.com>,
        Mark Bloch <markb@mellanox.com>,
        Tatyana E Nikolova <tatyana.e.nikolova@intel.com>,
        Matan Barak <matanb@mellanox.com>, Lijun Ou <oulijun@huawei.com>,
        "Wei Hu(Xavier)" <xavier.huwei@huawei.com>
References: <1479708496-9828-1-git-send-email-binoy.jayan@linaro.org>
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Cc: Faisal Latif <faisal.latif@intel.com>,
        Mustafa Ismail <mustafa.ismail@intel.com>,
        Mark Brown <broonie@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
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        target-devel@vger.kernel.org
From: Sagi Grimberg <sagi@grimberg.me>
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Date: Mon, 21 Nov 2016 09:36:22 +0200
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> diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
> index 6dd43f6..de80f56 100644
> --- a/drivers/infiniband/ulp/isert/ib_isert.c
> +++ b/drivers/infiniband/ulp/isert/ib_isert.c
> @@ -619,7 +619,7 @@
>  	mutex_unlock(&isert_np->mutex);
>
>  	isert_info("np %p: Allow accept_np to continue\n", isert_np);
> -	up(&isert_np->sem);
> +	complete(&isert_np->comp);
>  }
>
>  static void
> @@ -2311,7 +2311,7 @@ struct rdma_cm_id *
>  		isert_err("Unable to allocate struct isert_np\n");
>  		return -ENOMEM;
>  	}
> -	sema_init(&isert_np->sem, 0);
> +	init_completion(&isert_np->comp);

This is still racy, a connect event can complete just before we
init the completion and *will* get lost...

This code started off with a waitqueue which exposes the same
problem, see:
531b7bf4bd79 Target/iser: Fix iscsit_accept_np and rdma_cm racy flow

So, still NAK from me...