Hi Sylvain,
On 18.09.2017 13:08, Sylvain Lesne wrote:
Since this lock is acquired in both process and IRQ context, failing to
to disable IRQs when trying to acquire the lock in process context can
lead to deadlocks.
Signed-off-by: Sylvain Lesne <lesne@xxxxxxxxxxx>
---
I'm not sure that this is the "smartest" fix, but I think something
should be done to fix the spinlock usage in this driver (lockdep
agrees!).
I'm a bit unsure here as well, as introducing the irqsave spinlocks
here will be a bit costly time-wise.
Perhaps its better to move the addition of new descriptors in the IDLE
state from the ISR back the IRQ tasklet, as I've initially proposed in
v2 of this patch:
https://patchwork.kernel.org/patch/9805967/
This way, the lock will not be used from IRQ context any more and
the "normal" spinlock calls should be enough.
What do you think?
Thanks,
Stefan
---
drivers/dma/altera-msgdma.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)
diff --git a/drivers/dma/altera-msgdma.c b/drivers/dma/altera-msgdma.c
index 35cbf2365f68..339186f25a2a 100644
--- a/drivers/dma/altera-msgdma.c
+++ b/drivers/dma/altera-msgdma.c
@@ -212,11 +212,12 @@ struct msgdma_device {
static struct msgdma_sw_desc *msgdma_get_descriptor(struct msgdma_device *mdev)
{
struct msgdma_sw_desc *desc;
+ unsigned long flags;
- spin_lock_bh(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, flags);
desc = list_first_entry(&mdev->free_list, struct msgdma_sw_desc, node);
list_del(&desc->node);
- spin_unlock_bh(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, flags);
INIT_LIST_HEAD(&desc->tx_list);
@@ -306,13 +307,14 @@ static dma_cookie_t msgdma_tx_submit(struct dma_async_tx_descriptor *tx)
struct msgdma_device *mdev = to_mdev(tx->chan);
struct msgdma_sw_desc *new;
dma_cookie_t cookie;
+ unsigned long flags;
new = tx_to_desc(tx);
- spin_lock_bh(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, flags);
cookie = dma_cookie_assign(tx);
list_add_tail(&new->node, &mdev->pending_list);
- spin_unlock_bh(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, flags);
return cookie;
}
@@ -336,17 +338,18 @@ msgdma_prep_memcpy(struct dma_chan *dchan, dma_addr_t dma_dst,
struct msgdma_extended_desc *desc;
size_t copy;
u32 desc_cnt;
+ unsigned long irqflags;
desc_cnt = DIV_ROUND_UP(len, MSGDMA_MAX_TRANS_LEN);
- spin_lock_bh(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, irqflags);
if (desc_cnt > mdev->desc_free_cnt) {
spin_unlock_bh(&mdev->lock);
dev_dbg(mdev->dev, "mdev %p descs are not available\n", mdev);
return NULL;
}
mdev->desc_free_cnt -= desc_cnt;
- spin_unlock_bh(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, irqflags);
do {
/* Allocate and populate the descriptor */
@@ -397,18 +400,19 @@ msgdma_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl,
u32 desc_cnt = 0, i;
struct scatterlist *sg;
u32 stride;
+ unsigned long irqflags;
for_each_sg(sgl, sg, sg_len, i)
desc_cnt += DIV_ROUND_UP(sg_dma_len(sg), MSGDMA_MAX_TRANS_LEN);
- spin_lock_bh(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, irqflags);
if (desc_cnt > mdev->desc_free_cnt) {
spin_unlock_bh(&mdev->lock);
dev_dbg(mdev->dev, "mdev %p descs are not available\n", mdev);
return NULL;
}
mdev->desc_free_cnt -= desc_cnt;
- spin_unlock_bh(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, irqflags);
avail = sg_dma_len(sgl);
@@ -566,10 +570,11 @@ static void msgdma_start_transfer(struct msgdma_device *mdev)
static void msgdma_issue_pending(struct dma_chan *chan)
{
struct msgdma_device *mdev = to_mdev(chan);
+ unsigned long flags;
- spin_lock_bh(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, flags);
msgdma_start_transfer(mdev);
- spin_unlock_bh(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, flags);
}
/**
@@ -634,10 +639,11 @@ static void msgdma_free_descriptors(struct msgdma_device *mdev)
static void msgdma_free_chan_resources(struct dma_chan *dchan)
{
struct msgdma_device *mdev = to_mdev(dchan);
+ unsigned long flags;
- spin_lock_bh(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, flags);
msgdma_free_descriptors(mdev);
- spin_unlock_bh(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, flags);
kfree(mdev->sw_desq);
}
@@ -682,8 +688,9 @@ static void msgdma_tasklet(unsigned long data)
u32 count;
u32 __maybe_unused size;
u32 __maybe_unused status;
+ unsigned long flags;
- spin_lock(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, flags);
/* Read number of responses that are available */
count = ioread32(mdev->csr + MSGDMA_CSR_RESP_FILL_LEVEL);
@@ -704,7 +711,7 @@ static void msgdma_tasklet(unsigned long data)
msgdma_chan_desc_cleanup(mdev);
}
- spin_unlock(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, flags);
}
/**
Viele Grüße,
Stefan
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