Hello Olivier,
thanks for following up on my comment first. I really appreciate. - I
don't have access to the hardware anymore, so I cannot test changes myself.
This patch addresses IMHO three fixes. - Shouldn't it be split up into
three small junks so one could also later work w/ git bisect / separate
ack's? - That way it is an all or nothing thing. Please regard this
remark as cosmetics.
Am 20.09.2023 um 21:58 schrieb Olivier Dautricourt:
Sparse complains because we first take the lock in msgdma_tasklet -> move
locking to msgdma_chan_desc_cleanup.
In consequence, move calling of msgdma_chan_desc_cleanup outside of the
critical section of function msgdma_tasklet.
Use spin_unlock_irqsave/restore instead of just spinlock/unlock to keep
state of irqs while executing the callbacks.
What about the locking in the IRQ handler msgdma_irq_handler() itself? -
Shouldn't spin_unlock_irqsave/restore() be used there as well instead of
just spinlock/unlock()?
Remove list_del call in msgdma_chan_desc_cleanup, this should be the role
of msgdma_free_descriptor. In consequence replace list_add_tail with
list_move_tail in msgdma_free_descriptor. This fixes the path:
msgdma_free_chan_resources -> msgdma_free_descriptors ->
msgdma_free_desc_list -> msgdma_free_descriptor
which does __not__ seems to free correctly the descriptors as firsts nodes
where not removed from the specified list.
s/__not__/_not_/
s/seems/seem/
s/firsts/first/ => Actually I would omit it.
s/where/were/
"Fixes: <12 digits git hash> ("commit-message")" is missing [1] isn't it?
[1]
https://www.kernel.org/doc/html/latest/process/submitting-patches.html#using-reported-by-tested-by-reviewed-by-suggested-by-and-fixes
Signed-off-by: Olivier Dautricourt <olivierdautricourt@xxxxxxxxx>
---
Following Eric Schwarz comments on altera-msgdma driver not having some
of the fixes made to zynqmp-dma driver (which msgdma driver is based on):
This patch should address at least the spinlock part, it __has not__ been
tested yet so please don't accept it right away. I'm in the process of
getting a new hardware to test with. Meanwhile it is open to reviews
and even better if someone is able to test it.
drivers/dma/altera-msgdma.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/dma/altera-msgdma.c b/drivers/dma/altera-msgdma.c
index 4153c2edb049..c39937bfcdf1 100644
--- a/drivers/dma/altera-msgdma.c
+++ b/drivers/dma/altera-msgdma.c
@@ -233,7 +233,7 @@ static void msgdma_free_descriptor(struct msgdma_device *mdev,
struct msgdma_sw_desc *child, *next;
mdev->desc_free_cnt++;
- list_add_tail(&desc->node, &mdev->free_list);
+ list_move_tail(&desc->node, &mdev->free_list);
list_for_each_entry_safe(child, next, &desc->tx_list, node) {
mdev->desc_free_cnt++;
list_move_tail(&child->node, &mdev->free_list);
@@ -583,22 +583,25 @@ static void msgdma_issue_pending(struct dma_chan *chan)
static void msgdma_chan_desc_cleanup(struct msgdma_device *mdev)
{
struct msgdma_sw_desc *desc, *next;
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&mdev->lock, irqflags);
list_for_each_entry_safe(desc, next, &mdev->done_list, node) {
struct dmaengine_desc_callback cb;
- list_del(&desc->node);
-
dmaengine_desc_get_callback(&desc->async_tx, &cb);
if (dmaengine_desc_callback_valid(&cb)) {
- spin_unlock(&mdev->lock);
+ spin_unlock_irqrestore(&mdev->lock, irqflags);
dmaengine_desc_callback_invoke(&cb, NULL);
- spin_lock(&mdev->lock);
+ spin_lock_irqsave(&mdev->lock, irqflags);
}
/* Run any dependencies, then free the descriptor */
msgdma_free_descriptor(mdev, desc);
}
+
+ spin_unlock_irqrestore(&mdev->lock, irqflags);
}
/**
@@ -713,10 +716,11 @@ static void msgdma_tasklet(struct tasklet_struct *t)
}
msgdma_complete_descriptor(mdev);
- msgdma_chan_desc_cleanup(mdev);
}
spin_unlock_irqrestore(&mdev->lock, flags);
+
+ msgdma_chan_desc_cleanup(mdev);
}
/**
