diff mbox

[v4,7/8] DMA: Freescale: use spin_lock_bh instead of spin_lock_irqsave

Message ID 1397809071-5353-8-git-send-email-hongbo.zhang@freescale.com (mailing list archive)
State Rejected
Delegated to: Vinod Koul
Headers show

Commit Message

hongbo.zhang@freescale.com April 18, 2014, 8:17 a.m. UTC 
From: Hongbo Zhang <hongbo.zhang@freescale.com>

The usage of spin_lock_irqsave() is a stronger locking mechanism than is
required throughout the driver. The minimum locking required should be used
instead. Interrupts will be turned off and context will be saved, it is
unnecessary to use irqsave.

This patch changes all instances of spin_lock_irqsave() to spin_lock_bh(). All
manipulation of protected fields is done using tasklet context or weaker, which
makes spin_lock_bh() the correct choice.

Signed-off-by: Hongbo Zhang <hongbo.zhang@freescale.com>
Signed-off-by: Qiang Liu <qiang.liu@freescale.com>
---
 drivers/dma/fsldma.c |   25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

Comments

Vinod Koul May 2, 2014, 4:51 p.m. UTC | #1 
On Fri, Apr 18, 2014 at 04:17:50PM +0800, hongbo.zhang@freescale.com wrote:
> From: Hongbo Zhang <hongbo.zhang@freescale.com>
> 
> The usage of spin_lock_irqsave() is a stronger locking mechanism than is
> required throughout the driver. The minimum locking required should be used
> instead. Interrupts will be turned off and context will be saved, it is
> unnecessary to use irqsave.
> 
> This patch changes all instances of spin_lock_irqsave() to spin_lock_bh(). All
> manipulation of protected fields is done using tasklet context or weaker, which
> makes spin_lock_bh() the correct choice.
>

This doesnt apply, perhpas due to depends on 6/8
hongbo.zhang@freescale.com May 4, 2014, 8:40 a.m. UTC | #2 
On 05/03/2014 12:51 AM, Vinod Koul wrote:
> On Fri, Apr 18, 2014 at 04:17:50PM +0800, hongbo.zhang@freescale.com wrote:
>> From: Hongbo Zhang <hongbo.zhang@freescale.com>
>>
>> The usage of spin_lock_irqsave() is a stronger locking mechanism than is
>> required throughout the driver. The minimum locking required should be used
>> instead. Interrupts will be turned off and context will be saved, it is
>> unnecessary to use irqsave.
>>
>> This patch changes all instances of spin_lock_irqsave() to spin_lock_bh(). All
>> manipulation of protected fields is done using tasklet context or weaker, which
>> makes spin_lock_bh() the correct choice.
>>
> This doesnt apply, perhpas due to depends on 6/8
>
So let's wait for the review result of 6/8.


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diff mbox

Patch

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 374ca97..6e1c9b3 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -396,10 +396,9 @@  static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
 	struct fsldma_chan *chan = to_fsl_chan(tx->chan);
 	struct fsl_desc_sw *desc = tx_to_fsl_desc(tx);
 	struct fsl_desc_sw *child;
-	unsigned long flags;
 	dma_cookie_t cookie = -EINVAL;
 
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 
 	/*
 	 * assign cookies to all of the software descriptors
@@ -412,7 +411,7 @@  static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
 	/* put this transaction onto the tail of the pending queue */
 	append_ld_queue(chan, desc);
 
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 
 	return cookie;
 }
@@ -726,15 +725,14 @@  static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
 static void fsl_dma_free_chan_resources(struct dma_chan *dchan)
 {
 	struct fsldma_chan *chan = to_fsl_chan(dchan);
-	unsigned long flags;
 
 	chan_dbg(chan, "free all channel resources\n");
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 	fsldma_cleanup_descriptors(chan);
 	fsldma_free_desc_list(chan, &chan->ld_pending);
 	fsldma_free_desc_list(chan, &chan->ld_running);
 	fsldma_free_desc_list(chan, &chan->ld_completed);
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 
 	dma_pool_destroy(chan->desc_pool);
 	chan->desc_pool = NULL;
@@ -953,7 +951,6 @@  static int fsl_dma_device_control(struct dma_chan *dchan,
 {
 	struct dma_slave_config *config;
 	struct fsldma_chan *chan;
-	unsigned long flags;
 	int size;
 
 	if (!dchan)
@@ -963,7 +960,7 @@  static int fsl_dma_device_control(struct dma_chan *dchan,
 
 	switch (cmd) {
 	case DMA_TERMINATE_ALL:
-		spin_lock_irqsave(&chan->desc_lock, flags);
+		spin_lock_bh(&chan->desc_lock);
 
 		/* Halt the DMA engine */
 		dma_halt(chan);
@@ -974,7 +971,7 @@  static int fsl_dma_device_control(struct dma_chan *dchan,
 		fsldma_free_desc_list(chan, &chan->ld_completed);
 		chan->idle = true;
 
-		spin_unlock_irqrestore(&chan->desc_lock, flags);
+		spin_unlock_bh(&chan->desc_lock);
 		return 0;
 
 	case DMA_SLAVE_CONFIG:
@@ -1016,11 +1013,10 @@  static int fsl_dma_device_control(struct dma_chan *dchan,
 static void fsl_dma_memcpy_issue_pending(struct dma_chan *dchan)
 {
 	struct fsldma_chan *chan = to_fsl_chan(dchan);
-	unsigned long flags;
 
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 	fsl_chan_xfer_ld_queue(chan);
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 }
 
 /**
@@ -1119,11 +1115,10 @@  static irqreturn_t fsldma_chan_irq(int irq, void *data)
 static void dma_do_tasklet(unsigned long data)
 {
 	struct fsldma_chan *chan = (struct fsldma_chan *)data;
-	unsigned long flags;
 
 	chan_dbg(chan, "tasklet entry\n");
 
-	spin_lock_irqsave(&chan->desc_lock, flags);
+	spin_lock_bh(&chan->desc_lock);
 
 	/* the hardware is now idle and ready for more */
 	chan->idle = true;
@@ -1131,7 +1126,7 @@  static void dma_do_tasklet(unsigned long data)
 	/* Run all cleanup for descriptors which have been completed */
 	fsldma_cleanup_descriptors(chan);
 
-	spin_unlock_irqrestore(&chan->desc_lock, flags);
+	spin_unlock_bh(&chan->desc_lock);
 
 	chan_dbg(chan, "tasklet exit\n");
 }