Commit b89b6a86 authored by Bhaumik Bhatt's avatar Bhaumik Bhatt Committed by Manivannan Sadhasivam
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bus: mhi: host: Add spinlock to protect WP access when queueing TREs 



Protect WP accesses such that multiple threads queueing buffers for
incoming data do not race.

Meanwhile, if CONFIG_TRACE_IRQFLAGS is enabled, irq will be enabled once
__local_bh_enable_ip is called as part of write_unlock_bh. Hence, let's
take irqsave lock after TRE is generated to avoid running write_unlock_bh
when irqsave lock is held.

Cc: stable@vger.kernel.org
Fixes: 189ff97c ("bus: mhi: core: Add support for data transfer")
Signed-off-by: default avatarBhaumik Bhatt <bbhatt@codeaurora.org>
Signed-off-by: default avatarQiang Yu <quic_qianyu@quicinc.com>
Reviewed-by: default avatarJeffrey Hugo <quic_jhugo@quicinc.com>
Tested-by: default avatarJeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1702276972-41296-2-git-send-email-quic_qianyu@quicinc.com


Signed-off-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
parent 327ec5f7

drivers/bus/mhi/host/main.c

+13 −9
Original line number Diff line number Diff line
@@ -1124,17 +1124,15 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info, 
	if (unlikely(MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)))

		return -EIO;



	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);



	ret = mhi_is_ring_full(mhi_cntrl, tre_ring);

	if (unlikely(ret)) {

		ret = -EAGAIN;

		goto exit_unlock;

	}

	if (unlikely(ret))

		return -EAGAIN;



	ret = mhi_gen_tre(mhi_cntrl, mhi_chan, buf_info, mflags);

	if (unlikely(ret))

		goto exit_unlock;

		return ret;



	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);



	/* Packet is queued, take a usage ref to exit M3 if necessary

	 * for host->device buffer, balanced put is done on buffer completion
@@ -1154,7 +1152,6 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info, 
	if (dir == DMA_FROM_DEVICE)

		mhi_cntrl->runtime_put(mhi_cntrl);



exit_unlock:

	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);



	return ret;
@@ -1206,6 +1203,9 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, 
	int eot, eob, chain, bei;

	int ret;



	/* Protect accesses for reading and incrementing WP */

	write_lock_bh(&mhi_chan->lock);



	buf_ring = &mhi_chan->buf_ring;

	tre_ring = &mhi_chan->tre_ring;
@@ -1223,9 +1223,11 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, 


	if (!info->pre_mapped) {

		ret = mhi_cntrl->map_single(mhi_cntrl, buf_info);

		if (ret)

		if (ret) {

			write_unlock_bh(&mhi_chan->lock);

			return ret;

		}

	}



	eob = !!(flags & MHI_EOB);

	eot = !!(flags & MHI_EOT);
@@ -1241,6 +1243,8 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, 
	mhi_add_ring_element(mhi_cntrl, tre_ring);

	mhi_add_ring_element(mhi_cntrl, buf_ring);



	write_unlock_bh(&mhi_chan->lock);



	return 0;

}