linux-kernel - Re: [PATCH] bus: mhi: ep: Do not allocate event ring element on stack

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Message-ID: <20231017073642.GA5274@thinkpad>
Date:   Tue, 17 Oct 2023 13:06:42 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     mhi@...ts.linux.dev
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_msarkar@...cinc.com, schintav@...cinc.com,
        stable@...r.kernel.org
Subject: Re: [PATCH] bus: mhi: ep: Do not allocate event ring element on stack

On Fri, Sep 01, 2023 at 01:05:02PM +0530, Manivannan Sadhasivam wrote:
> It is possible that the host controller driver would use DMA framework to
> write the event ring element. So avoid allocating event ring element on the
> stack as DMA cannot work on vmalloc memory.
> 
> Cc: stable@...r.kernel.org
> Fixes: 961aeb689224 ("bus: mhi: ep: Add support for sending events to the host")
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Applied to mhi-next!

- Mani

> ---
>  drivers/bus/mhi/ep/main.c | 52 +++++++++++++++++++++++++--------------
>  1 file changed, 34 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index 600881808982..66ca470bf302 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -71,45 +71,61 @@ static int mhi_ep_send_event(struct mhi_ep_cntrl *mhi_cntrl, u32 ring_idx,
>  static int mhi_ep_send_completion_event(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring,
>  					struct mhi_ring_element *tre, u32 len, enum mhi_ev_ccs code)
>  {
> -	struct mhi_ring_element event = {};
> +	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
> +	int ret;
> +
> +	event->ptr = cpu_to_le64(ring->rbase + ring->rd_offset * sizeof(*tre));
> +	event->dword[0] = MHI_TRE_EV_DWORD0(code, len);
> +	event->dword[1] = MHI_TRE_EV_DWORD1(ring->ch_id, MHI_PKT_TYPE_TX_EVENT);
>  
> -	event.ptr = cpu_to_le64(ring->rbase + ring->rd_offset * sizeof(*tre));
> -	event.dword[0] = MHI_TRE_EV_DWORD0(code, len);
> -	event.dword[1] = MHI_TRE_EV_DWORD1(ring->ch_id, MHI_PKT_TYPE_TX_EVENT);
> +	ret = mhi_ep_send_event(mhi_cntrl, ring->er_index, event, MHI_TRE_DATA_GET_BEI(tre));
> +	kfree(event);
>  
> -	return mhi_ep_send_event(mhi_cntrl, ring->er_index, &event, MHI_TRE_DATA_GET_BEI(tre));
> +	return ret;
>  }
>  
>  int mhi_ep_send_state_change_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state state)
>  {
> -	struct mhi_ring_element event = {};
> +	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
> +	int ret;
> +
> +	event->dword[0] = MHI_SC_EV_DWORD0(state);
> +	event->dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_STATE_CHANGE_EVENT);
>  
> -	event.dword[0] = MHI_SC_EV_DWORD0(state);
> -	event.dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_STATE_CHANGE_EVENT);
> +	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
> +	kfree(event);
>  
> -	return mhi_ep_send_event(mhi_cntrl, 0, &event, 0);
> +	return ret;
>  }
>  
>  int mhi_ep_send_ee_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ee_type exec_env)
>  {
> -	struct mhi_ring_element event = {};
> +	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
> +	int ret;
> +
> +	event->dword[0] = MHI_EE_EV_DWORD0(exec_env);
> +	event->dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_EE_EVENT);
>  
> -	event.dword[0] = MHI_EE_EV_DWORD0(exec_env);
> -	event.dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_EE_EVENT);
> +	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
> +	kfree(event);
>  
> -	return mhi_ep_send_event(mhi_cntrl, 0, &event, 0);
> +	return ret;
>  }
>  
>  static int mhi_ep_send_cmd_comp_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ev_ccs code)
>  {
> +	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
>  	struct mhi_ep_ring *ring = &mhi_cntrl->mhi_cmd->ring;
> -	struct mhi_ring_element event = {};
> +	int ret;
> +
> +	event->ptr = cpu_to_le64(ring->rbase + ring->rd_offset * sizeof(struct mhi_ring_element));
> +	event->dword[0] = MHI_CC_EV_DWORD0(code);
> +	event->dword[1] = MHI_CC_EV_DWORD1(MHI_PKT_TYPE_CMD_COMPLETION_EVENT);
>  
> -	event.ptr = cpu_to_le64(ring->rbase + ring->rd_offset * sizeof(struct mhi_ring_element));
> -	event.dword[0] = MHI_CC_EV_DWORD0(code);
> -	event.dword[1] = MHI_CC_EV_DWORD1(MHI_PKT_TYPE_CMD_COMPLETION_EVENT);
> +	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
> +	kfree(event);
>  
> -	return mhi_ep_send_event(mhi_cntrl, 0, &event, 0);
> +	return ret;
>  }
>  
>  static int mhi_ep_process_cmd_ring(struct mhi_ep_ring *ring, struct mhi_ring_element *el)
> -- 
> 2.25.1
> 

-- 
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