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Subject[PATCH 1/3] dmaengine: at_hdmac: replace spin_lock* with irqsave variants
Date
dmaengine routines can be called from interrupt context and with
interrupts disabled. Whereas spin_unlock_bh can't be called from
such contexts. So this patch converts all spin_lock* routines
to irqsave variants.

Also, spin_lock() used in tasklet is converted to irqsave variants,
as tasklet can be interrupted, and dma requests from such interruptions
may also call spin_lock.

Idea from dw_dmac patch by Viresh Kumar.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
drivers/dma/at_hdmac.c | 52 +++++++++++++++++++++++++++--------------------
1 files changed, 30 insertions(+), 22 deletions(-)
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 6a483ea..fd87b96 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -107,10 +107,11 @@ static struct at_desc *atc_desc_get(struct at_dma_chan *atchan)
{
struct at_desc *desc, *_desc;
struct at_desc *ret = NULL;
+ unsigned long flags;
unsigned int i = 0;
LIST_HEAD(tmp_list);

- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);
list_for_each_entry_safe(desc, _desc, &atchan->free_list, desc_node) {
i++;
if (async_tx_test_ack(&desc->txd)) {
@@ -121,7 +122,7 @@ static struct at_desc *atc_desc_get(struct at_dma_chan *atchan)
dev_dbg(chan2dev(&atchan->chan_common),
"desc %p not ACKed\n", desc);
}
- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
dev_vdbg(chan2dev(&atchan->chan_common),
"scanned %u descriptors on freelist\n", i);

@@ -129,9 +130,9 @@ static struct at_desc *atc_desc_get(struct at_dma_chan *atchan)
if (!ret) {
ret = atc_alloc_descriptor(&atchan->chan_common, GFP_ATOMIC);
if (ret) {
- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);
atchan->descs_allocated++;
- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
} else {
dev_err(chan2dev(&atchan->chan_common),
"not enough descriptors available\n");
@@ -150,8 +151,9 @@ static void atc_desc_put(struct at_dma_chan *atchan, struct at_desc *desc)
{
if (desc) {
struct at_desc *child;
+ unsigned long flags;

- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);
list_for_each_entry(child, &desc->tx_list, desc_node)
dev_vdbg(chan2dev(&atchan->chan_common),
"moving child desc %p to freelist\n",
@@ -160,7 +162,7 @@ static void atc_desc_put(struct at_dma_chan *atchan, struct at_desc *desc)
dev_vdbg(chan2dev(&atchan->chan_common),
"moving desc %p to freelist\n", desc);
list_add(&desc->desc_node, &atchan->free_list);
- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
}
}

@@ -471,8 +473,9 @@ static void atc_handle_cyclic(struct at_dma_chan *atchan)
static void atc_tasklet(unsigned long data)
{
struct at_dma_chan *atchan = (struct at_dma_chan *)data;
+ unsigned long flags;

- spin_lock(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);
if (test_and_clear_bit(ATC_IS_ERROR, &atchan->status))
atc_handle_error(atchan);
else if (test_bit(ATC_IS_CYCLIC, &atchan->status))
@@ -480,7 +483,7 @@ static void atc_tasklet(unsigned long data)
else
atc_advance_work(atchan);

- spin_unlock(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
}

static irqreturn_t at_dma_interrupt(int irq, void *dev_id)
@@ -539,8 +542,9 @@ static dma_cookie_t atc_tx_submit(struct dma_async_tx_descriptor *tx)
struct at_desc *desc = txd_to_at_desc(tx);
struct at_dma_chan *atchan = to_at_dma_chan(tx->chan);
dma_cookie_t cookie;
+ unsigned long flags;

- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);
cookie = atc_assign_cookie(atchan, desc);

if (list_empty(&atchan->active_list)) {
@@ -554,7 +558,7 @@ static dma_cookie_t atc_tx_submit(struct dma_async_tx_descriptor *tx)
list_add_tail(&desc->desc_node, &atchan->queue);
}

- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);

return cookie;
}
@@ -927,28 +931,29 @@ static int atc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
struct at_dma_chan *atchan = to_at_dma_chan(chan);
struct at_dma *atdma = to_at_dma(chan->device);
int chan_id = atchan->chan_common.chan_id;
+ unsigned long flags;

LIST_HEAD(list);

dev_vdbg(chan2dev(chan), "atc_control (%d)\n", cmd);

if (cmd == DMA_PAUSE) {
- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);

dma_writel(atdma, CHER, AT_DMA_SUSP(chan_id));
set_bit(ATC_IS_PAUSED, &atchan->status);

- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
} else if (cmd == DMA_RESUME) {
if (!test_bit(ATC_IS_PAUSED, &atchan->status))
return 0;

- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);

dma_writel(atdma, CHDR, AT_DMA_RES(chan_id));
clear_bit(ATC_IS_PAUSED, &atchan->status);

- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
} else if (cmd == DMA_TERMINATE_ALL) {
struct at_desc *desc, *_desc;
/*
@@ -957,7 +962,7 @@ static int atc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
* channel. We still have to poll the channel enable bit due
* to AHB/HSB limitations.
*/
- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);

/* disabling channel: must also remove suspend state */
dma_writel(atdma, CHDR, AT_DMA_RES(chan_id) | atchan->mask);
@@ -978,7 +983,7 @@ static int atc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
/* if channel dedicated to cyclic operations, free it */
clear_bit(ATC_IS_CYCLIC, &atchan->status);

- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
} else {
return -ENXIO;
}
@@ -1004,9 +1009,10 @@ atc_tx_status(struct dma_chan *chan,
struct at_dma_chan *atchan = to_at_dma_chan(chan);
dma_cookie_t last_used;
dma_cookie_t last_complete;
+ unsigned long flags;
enum dma_status ret;

- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);

last_complete = atchan->completed_cookie;
last_used = chan->cookie;
@@ -1021,7 +1027,7 @@ atc_tx_status(struct dma_chan *chan,
ret = dma_async_is_complete(cookie, last_complete, last_used);
}

- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);

if (ret != DMA_SUCCESS)
dma_set_tx_state(txstate, last_complete, last_used,
@@ -1046,6 +1052,7 @@ atc_tx_status(struct dma_chan *chan,
static void atc_issue_pending(struct dma_chan *chan)
{
struct at_dma_chan *atchan = to_at_dma_chan(chan);
+ unsigned long flags;

dev_vdbg(chan2dev(chan), "issue_pending\n");

@@ -1053,11 +1060,11 @@ static void atc_issue_pending(struct dma_chan *chan)
if (test_bit(ATC_IS_CYCLIC, &atchan->status))
return;

- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);
if (!atc_chan_is_enabled(atchan)) {
atc_advance_work(atchan);
}
- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);
}

/**
@@ -1073,6 +1080,7 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
struct at_dma *atdma = to_at_dma(chan->device);
struct at_desc *desc;
struct at_dma_slave *atslave;
+ unsigned long flags;
int i;
u32 cfg;
LIST_HEAD(tmp_list);
@@ -1116,11 +1124,11 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
list_add_tail(&desc->desc_node, &tmp_list);
}

- spin_lock_bh(&atchan->lock);
+ spin_lock_irqsave(&atchan->lock, flags);
atchan->descs_allocated = i;
list_splice(&tmp_list, &atchan->free_list);
atchan->completed_cookie = chan->cookie = 1;
- spin_unlock_bh(&atchan->lock);
+ spin_unlock_irqrestore(&atchan->lock, flags);

/* channel parameters */
channel_writel(atchan, CFG, cfg);
--
1.7.3
--
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