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References: <20210322204633.102581-1-emmanuel.grumbach@intel.com> <20210322204633.102581-2-emmanuel.grumbach@intel.com>
In-Reply-To: <20210322204633.102581-2-emmanuel.grumbach@intel.com>
From:   Emmanuel Grumbach <egrumbach@gmail.com>
Date:   Tue, 23 Mar 2021 17:15:47 +0200
Message-ID: <CANUX_P3w9gkRsvddx-fHhHngdEbe6g5xXLmjyquC1DMXZtU2MQ@mail.gmail.com>
Subject: Re: [PATCH 1/5] mei: allow map and unmap of client dma buffer only
 for disconnected client
To:     Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc:     Kalle Valo <kvalo@codeaurora.org>,
        "Berg, Johannes" <johannes@sipsolutions.net>,
        linux-wireless <linux-wireless@vger.kernel.org>, luca@coelho.fi,
        Tomas Winkler <tomas.winkler@intel.com>
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On Mon, Mar 22, 2021 at 10:49 PM Emmanuel Grumbach
<emmanuel.grumbach@intel.com> wrote:
>
> From: Tomas Winkler <tomas.winkler@intel.com>
>
> Allow map and unmap of the client dma buffer only when the client is not
> connected. The functions return -EPROTO if the client is already connected.
> This is to fix the race when traffic may start or stop when buffer
> is not available.
>
> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
> Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

This one has been taken by Greg through his tree so I'll drop it.
I won't resend the series for this though.

> ---
>  drivers/misc/mei/client.c | 17 +++++++----------
>  1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
> index 4378a9b25848..2cc370adb238 100644
> --- a/drivers/misc/mei/client.c
> +++ b/drivers/misc/mei/client.c
> @@ -2286,8 +2286,8 @@ int mei_cl_dma_alloc_and_map(struct mei_cl *cl, const struct file *fp,
>         if (buffer_id == 0)
>                 return -EINVAL;
>
> -       if (!mei_cl_is_connected(cl))
> -               return -ENODEV;
> +       if (mei_cl_is_connected(cl))
> +               return -EPROTO;
>
>         if (cl->dma_mapped)
>                 return -EPROTO;
> @@ -2327,9 +2327,7 @@ int mei_cl_dma_alloc_and_map(struct mei_cl *cl, const struct file *fp,
>
>         mutex_unlock(&dev->device_lock);
>         wait_event_timeout(cl->wait,
> -                          cl->dma_mapped ||
> -                          cl->status ||
> -                          !mei_cl_is_connected(cl),
> +                          cl->dma_mapped || cl->status,
>                            mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT));
>         mutex_lock(&dev->device_lock);
>
> @@ -2376,8 +2374,9 @@ int mei_cl_dma_unmap(struct mei_cl *cl, const struct file *fp)
>                 return -EOPNOTSUPP;
>         }
>
> -       if (!mei_cl_is_connected(cl))
> -               return -ENODEV;
> +       /* do not allow unmap for connected client */
> +       if (mei_cl_is_connected(cl))
> +               return -EPROTO;
>
>         if (!cl->dma_mapped)
>                 return -EPROTO;
> @@ -2405,9 +2404,7 @@ int mei_cl_dma_unmap(struct mei_cl *cl, const struct file *fp)
>
>         mutex_unlock(&dev->device_lock);
>         wait_event_timeout(cl->wait,
> -                          !cl->dma_mapped ||
> -                          cl->status ||
> -                          !mei_cl_is_connected(cl),
> +                          !cl->dma_mapped || cl->status,
>                            mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT));
>         mutex_lock(&dev->device_lock);
>
> --
> 2.25.1
>