From: Leon Romanovsky <leon@kernel.org>
To: Frank Huang <tigerinxm@gmail.com>
Cc: linux-rdma@vger.kernel.org
Subject: Re: a strange lock
Date: Mon, 3 Feb 2020 15:30:50 +0200 [thread overview]
Message-ID: <20200203133050.GP414821@unreal> (raw)
In-Reply-To: <CAKC_zSu1SQgNT5Yyg49qe+r+hux-3oCqzZPvH0b7pjaPz2x2Rw@mail.gmail.com>
On Mon, Feb 03, 2020 at 08:31:10PM +0800, Frank Huang wrote:
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/infiniband/core/cma.c#n1832
>
> /*
> * Wait for any active callback to finish. New callbacks will find
> * the id_priv state set to destroying and abort.
> */
> mutex_lock(&id_priv->handler_mutex);
> mutex_unlock(&id_priv->handler_mutex);
>
> It does nothing between the lock, what 's the meaning of it?
It is a way to implement wait_for_completion paradigm, by ensuring
that all cm_id works or will see RDMA_CM_DESTROYING state (they need
to take handler_mutex, before every call to cma_exch), or will
complete their execution and release handler_mutex.
Thanks
prev parent reply other threads:[~2020-02-03 13:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-03 12:31 a strange lock Frank Huang
2020-02-03 13:30 ` Leon Romanovsky [this message]
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