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Commit 4c374fc7 authored by Ludovic Desroches's avatar Ludovic Desroches Committed by Vinod Koul
Browse files

dmaengine: at_xdmac: lock fixes 



Using _bh variant for spin locks causes this kind of warning:
Starting logging: ------------[ cut here ]------------
WARNING: CPU: 0 PID: 3 at /ssd_drive/linux/kernel/softirq.c:151
__local_bh_enable_ip+0xe8/0xf4()
Modules linked in:
CPU: 0 PID: 3 Comm: ksoftirqd/0 Not tainted 4.1.0-rc2+ #94
Hardware name: Atmel SAMA5
[<c0013c04>] (unwind_backtrace) from [<c00118a4>] (show_stack+0x10/0x14)
[<c00118a4>] (show_stack) from [<c001bbcc>]
(warn_slowpath_common+0x80/0xac)
[<c001bbcc>] (warn_slowpath_common) from [<c001bc14>]
(warn_slowpath_null+0x1c/0x24)
[<c001bc14>] (warn_slowpath_null) from [<c001e28c>]
(__local_bh_enable_ip+0xe8/0xf4)
[<c001e28c>] (__local_bh_enable_ip) from [<c01fdbd0>]
(at_xdmac_device_terminate_all+0xf4/0x100)
[<c01fdbd0>] (at_xdmac_device_terminate_all) from [<c02221a4>]
(atmel_complete_tx_dma+0x34/0xf4)
[<c02221a4>] (atmel_complete_tx_dma) from [<c01fe4ac>]
(at_xdmac_tasklet+0x14c/0x1ac)
[<c01fe4ac>] (at_xdmac_tasklet) from [<c001de58>]
(tasklet_action+0x68/0xb4)
[<c001de58>] (tasklet_action) from [<c001dfdc>]
(__do_softirq+0xfc/0x238)
[<c001dfdc>] (__do_softirq) from [<c001e140>] (run_ksoftirqd+0x28/0x34)
[<c001e140>] (run_ksoftirqd) from [<c0033a3c>]
(smpboot_thread_fn+0x138/0x18c)
[<c0033a3c>] (smpboot_thread_fn) from [<c0030e7c>] (kthread+0xdc/0xf0)
[<c0030e7c>] (kthread) from [<c000f480>] (ret_from_fork+0x14/0x34)
---[ end trace b57b14a99c1d8812 ]---

It comes from the fact that devices can called some code from the DMA
controller with irq disabled. _bh variant is not intended to be used in
this case since it can enable irqs. Switch to irqsave/irqrestore variant to
avoid this situation.

Signed-off-by: default avatarLudovic Desroches <ludovic.desroches@atmel.com>
Cc: stable@vger.kernel.org # 4.0 and later
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent d4a4f75c

drivers/dma/at_xdmac.c

+43 −32
Original line number Diff line number Diff line
@@ -415,8 +415,9 @@ static dma_cookie_t at_xdmac_tx_submit(struct dma_async_tx_descriptor *tx) 
	struct at_xdmac_desc	*desc = txd_to_at_desc(tx);

	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(tx->chan);

	dma_cookie_t		cookie;

	unsigned long		irqflags;



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, irqflags);

	cookie = dma_cookie_assign(tx);



	dev_vdbg(chan2dev(tx->chan), "%s: atchan 0x%p, add desc 0x%p to xfers_list\n",
@@ -425,7 +426,7 @@ static dma_cookie_t at_xdmac_tx_submit(struct dma_async_tx_descriptor *tx) 
	if (list_is_singular(&atchan->xfers_list))

		at_xdmac_start_xfer(atchan, desc);



	spin_unlock_bh(&atchan->lock);

	spin_unlock_irqrestore(&atchan->lock, irqflags);

	return cookie;

}
@@ -563,6 +564,8 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, 
	struct scatterlist	*sg;

	int			i;

	unsigned int		xfer_size = 0;

	unsigned long		irqflags;

	struct dma_async_tx_descriptor	*ret = NULL;



	if (!sgl)

		return NULL;
@@ -578,7 +581,7 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, 
		 flags);



	/* Protect dma_sconfig field that can be modified by set_slave_conf. */

	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, irqflags);



	/* Prepare descriptors. */

	for_each_sg(sgl, sg, sg_len, i) {
@@ -589,8 +592,7 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, 
		mem = sg_dma_address(sg);

		if (unlikely(!len)) {

			dev_err(chan2dev(chan), "sg data length is zero\n");

			spin_unlock_bh(&atchan->lock);

			return NULL;

			goto spin_unlock;

		}

		dev_dbg(chan2dev(chan), "%s: * sg%d len=%u, mem=0x%08x\n",

			 __func__, i, len, mem);
@@ -600,8 +602,7 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, 
			dev_err(chan2dev(chan), "can't get descriptor\n");

			if (first)

				list_splice_init(&first->descs_list, &atchan->free_descs_list);

			spin_unlock_bh(&atchan->lock);

			return NULL;

			goto spin_unlock;

		}



		/* Linked list descriptor setup. */
@@ -645,13 +646,15 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, 
		xfer_size += len;

	}



	spin_unlock_bh(&atchan->lock);



	first->tx_dma_desc.flags = flags;

	first->xfer_size = xfer_size;

	first->direction = direction;

	ret = &first->tx_dma_desc;



	return &first->tx_dma_desc;

spin_unlock:

	spin_unlock_irqrestore(&atchan->lock, irqflags);

	return ret;

}



static struct dma_async_tx_descriptor *
@@ -664,6 +667,7 @@ at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr, 
	struct at_xdmac_desc	*first = NULL, *prev = NULL;

	unsigned int		periods = buf_len / period_len;

	int			i;

	unsigned long		irqflags;



	dev_dbg(chan2dev(chan), "%s: buf_addr=%pad, buf_len=%zd, period_len=%zd, dir=%s, flags=0x%lx\n",

		__func__, &buf_addr, buf_len, period_len,
@@ -682,16 +686,16 @@ at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr, 
	for (i = 0; i < periods; i++) {

		struct at_xdmac_desc	*desc = NULL;



		spin_lock_bh(&atchan->lock);

		spin_lock_irqsave(&atchan->lock, irqflags);

		desc = at_xdmac_get_desc(atchan);

		if (!desc) {

			dev_err(chan2dev(chan), "can't get descriptor\n");

			if (first)

				list_splice_init(&first->descs_list, &atchan->free_descs_list);

			spin_unlock_bh(&atchan->lock);

			spin_unlock_irqrestore(&atchan->lock, irqflags);

			return NULL;

		}

		spin_unlock_bh(&atchan->lock);

		spin_unlock_irqrestore(&atchan->lock, irqflags);

		dev_dbg(chan2dev(chan),

			"%s: desc=0x%p, tx_dma_desc.phys=%pad\n",

			__func__, desc, &desc->tx_dma_desc.phys);
@@ -766,6 +770,7 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, 
					| AT_XDMAC_CC_SIF(0)

					| AT_XDMAC_CC_MBSIZE_SIXTEEN

					| AT_XDMAC_CC_TYPE_MEM_TRAN;

	unsigned long		irqflags;



	dev_dbg(chan2dev(chan), "%s: src=%pad, dest=%pad, len=%zd, flags=0x%lx\n",

		__func__, &src, &dest, len, flags);
@@ -798,9 +803,9 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, 


		dev_dbg(chan2dev(chan), "%s: remaining_size=%zu\n", __func__, remaining_size);



		spin_lock_bh(&atchan->lock);

		spin_lock_irqsave(&atchan->lock, irqflags);

		desc = at_xdmac_get_desc(atchan);

		spin_unlock_bh(&atchan->lock);

		spin_unlock_irqrestore(&atchan->lock, irqflags);

		if (!desc) {

			dev_err(chan2dev(chan), "can't get descriptor\n");

			if (first)
@@ -886,6 +891,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie, 
	int			residue;

	u32			cur_nda, mask, value;

	u8			dwidth = 0;

	unsigned long		flags;



	ret = dma_cookie_status(chan, cookie, txstate);

	if (ret == DMA_COMPLETE)
@@ -894,7 +900,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie, 
	if (!txstate)

		return ret;



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, flags);



	desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, xfer_node);
@@ -904,8 +910,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie, 
	 */

	if (!desc->active_xfer) {

		dma_set_residue(txstate, desc->xfer_size);

		spin_unlock_bh(&atchan->lock);

		return ret;

		goto spin_unlock;

	}



	residue = desc->xfer_size;
@@ -936,14 +941,14 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie, 
	}

	residue += at_xdmac_chan_read(atchan, AT_XDMAC_CUBC) << dwidth;



	spin_unlock_bh(&atchan->lock);



	dma_set_residue(txstate, residue);



	dev_dbg(chan2dev(chan),

		 "%s: desc=0x%p, tx_dma_desc.phys=%pad, tx_status=%d, cookie=%d, residue=%d\n",

		 __func__, desc, &desc->tx_dma_desc.phys, ret, cookie, residue);



spin_unlock:

	spin_unlock_irqrestore(&atchan->lock, flags);

	return ret;

}
@@ -964,8 +969,9 @@ static void at_xdmac_remove_xfer(struct at_xdmac_chan *atchan, 
static void at_xdmac_advance_work(struct at_xdmac_chan *atchan)

{

	struct at_xdmac_desc	*desc;

	unsigned long		flags;



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, flags);



	/*

	 * If channel is enabled, do nothing, advance_work will be triggered
@@ -980,7 +986,7 @@ static void at_xdmac_advance_work(struct at_xdmac_chan *atchan) 
			at_xdmac_start_xfer(atchan, desc);

	}



	spin_unlock_bh(&atchan->lock);

	spin_unlock_irqrestore(&atchan->lock, flags);

}



static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
@@ -1116,12 +1122,13 @@ static int at_xdmac_device_config(struct dma_chan *chan, 
{

	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);

	int ret;

	unsigned long		flags;



	dev_dbg(chan2dev(chan), "%s\n", __func__);



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, flags);

	ret = at_xdmac_set_slave_config(chan, config);

	spin_unlock_bh(&atchan->lock);

	spin_unlock_irqrestore(&atchan->lock, flags);



	return ret;

}
@@ -1130,18 +1137,19 @@ static int at_xdmac_device_pause(struct dma_chan *chan) 
{

	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);

	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);

	unsigned long		flags;



	dev_dbg(chan2dev(chan), "%s\n", __func__);



	if (test_and_set_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status))

		return 0;



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, flags);

	at_xdmac_write(atxdmac, AT_XDMAC_GRWS, atchan->mask);

	while (at_xdmac_chan_read(atchan, AT_XDMAC_CC)

	       & (AT_XDMAC_CC_WRIP | AT_XDMAC_CC_RDIP))

		cpu_relax();

	spin_unlock_bh(&atchan->lock);

	spin_unlock_irqrestore(&atchan->lock, flags);



	return 0;

}
@@ -1150,18 +1158,19 @@ static int at_xdmac_device_resume(struct dma_chan *chan) 
{

	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);

	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);

	unsigned long		flags;



	dev_dbg(chan2dev(chan), "%s\n", __func__);



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, flags);

	if (!at_xdmac_chan_is_paused(atchan)) {

		spin_unlock_bh(&atchan->lock);

		spin_unlock_irqrestore(&atchan->lock, flags);

		return 0;

	}



	at_xdmac_write(atxdmac, AT_XDMAC_GRWR, atchan->mask);

	clear_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);

	spin_unlock_bh(&atchan->lock);

	spin_unlock_irqrestore(&atchan->lock, flags);



	return 0;

}
@@ -1171,10 +1180,11 @@ static int at_xdmac_device_terminate_all(struct dma_chan *chan) 
	struct at_xdmac_desc	*desc, *_desc;

	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);

	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);

	unsigned long		flags;



	dev_dbg(chan2dev(chan), "%s\n", __func__);



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, flags);

	at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);

	while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)

		cpu_relax();
@@ -1184,7 +1194,7 @@ static int at_xdmac_device_terminate_all(struct dma_chan *chan) 
		at_xdmac_remove_xfer(atchan, desc);



	clear_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status);

	spin_unlock_bh(&atchan->lock);

	spin_unlock_irqrestore(&atchan->lock, flags);



	return 0;

}
@@ -1194,8 +1204,9 @@ static int at_xdmac_alloc_chan_resources(struct dma_chan *chan) 
	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);

	struct at_xdmac_desc	*desc;

	int			i;

	unsigned long		flags;



	spin_lock_bh(&atchan->lock);

	spin_lock_irqsave(&atchan->lock, flags);



	if (at_xdmac_chan_is_enabled(atchan)) {

		dev_err(chan2dev(chan),
@@ -1226,7 +1237,7 @@ static int at_xdmac_alloc_chan_resources(struct dma_chan *chan) 
	dev_dbg(chan2dev(chan), "%s: allocated %d descriptors\n", __func__, i);



spin_unlock:

	spin_unlock_bh(&atchan->lock);

	spin_unlock_irqrestore(&atchan->lock, flags);

	return i;

}