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dmaengine: at_hdmac: Fix deadlocks

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Fix the following deadlocks:
1/ atc_handle_cyclic() and atc_chain_complete() called
dmaengine_desc_get_callback_invoke() while wrongly holding the
atchan->lock. Clients can set the callback to dmaengine_terminate_sync()
which will end up trying to get the same lock, thus a deadlock occurred.
2/ dma_run_dependencies() was called with the atchan->lock held, but the
method calls device_issue_pending() which tries to get the same lock,
and so a deadlock occurred.

The driver must not hold the lock when invoking the callback or when
running dependencies. Releasing the spinlock within a called function
before calling the callback is not a nice thing to do -> called functions
become non-atomic when called within an atomic region. Thus the lock is
now taken in the child routines whereever is needed.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Link: https://lore.kernel.org/r/20200123140237.125799-6-tudor.ambarus@microchip.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Tudor Ambarus 2020-01-23 14:03:11 +00:00 committed by Vinod Koul
parent 247b4d83d6
commit 078a650614
1 changed files with 39 additions and 35 deletions
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74
drivers/dma/at_hdmac.c
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@ -426,17 +426,19 @@ static int atc_get_bytes_left(struct dma_chan *chan, dma_cookie_t cookie)
* atc_chain_complete - finish work for one transaction chain
* @atchan: channel we work on
* @desc: descriptor at the head of the chain we want do complete
*
* Called with atchan->lock held and bh disabled */
*/
static void
atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
{
struct dma_async_tx_descriptor *txd = &desc->txd;
struct at_dma *atdma = to_at_dma(atchan->chan_common.device);
unsigned long flags;
dev_vdbg(chan2dev(&atchan->chan_common),
"descriptor %u complete\n", txd->cookie);
spin_lock_irqsave(&atchan->lock, flags);
/* mark the descriptor as complete for non cyclic cases only */
if (!atc_chan_is_cyclic(atchan))
dma_cookie_complete(txd);
@ -453,16 +455,13 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
/* move myself to free_list */
list_move(&desc->desc_node, &atchan->free_list);
spin_unlock_irqrestore(&atchan->lock, flags);
dma_descriptor_unmap(txd);
/* for cyclic transfers,
* no need to replay callback function while stopping */
if (!atc_chan_is_cyclic(atchan)) {
/*
* The API requires that no submissions are done from a
* callback, so we don't need to drop the lock here
*/
if (!atc_chan_is_cyclic(atchan))
dmaengine_desc_get_callback_invoke(txd, NULL);
}
dma_run_dependencies(txd);
}
@ -480,9 +479,12 @@ static void atc_complete_all(struct at_dma_chan *atchan)
{
struct at_desc *desc, *_desc;
LIST_HEAD(list);
unsigned long flags;
dev_vdbg(chan2dev(&atchan->chan_common), "complete all\n");
spin_lock_irqsave(&atchan->lock, flags);
/*
* Submit queued descriptors ASAP, i.e. before we go through
* the completed ones.
@ -494,6 +496,8 @@ static void atc_complete_all(struct at_dma_chan *atchan)
/* empty queue list by moving descriptors (if any) to active_list */
list_splice_init(&atchan->queue, &atchan->active_list);
spin_unlock_irqrestore(&atchan->lock, flags);
list_for_each_entry_safe(desc, _desc, &list, desc_node)
atc_chain_complete(atchan, desc);
}
@ -501,38 +505,44 @@ static void atc_complete_all(struct at_dma_chan *atchan)
/**
* atc_advance_work - at the end of a transaction, move forward
* @atchan: channel where the transaction ended
*
* Called with atchan->lock held and bh disabled
*/
static void atc_advance_work(struct at_dma_chan *atchan)
{
unsigned long flags;
int ret;
dev_vdbg(chan2dev(&atchan->chan_common), "advance_work\n");
if (atc_chan_is_enabled(atchan))
spin_lock_irqsave(&atchan->lock, flags);
ret = atc_chan_is_enabled(atchan);
spin_unlock_irqrestore(&atchan->lock, flags);
if (ret)
return;
if (list_empty(&atchan->active_list) ||
list_is_singular(&atchan->active_list)) {
atc_complete_all(atchan);
} else {
atc_chain_complete(atchan, atc_first_active(atchan));
/* advance work */
atc_dostart(atchan, atc_first_active(atchan));
}
list_is_singular(&atchan->active_list))
return atc_complete_all(atchan);
atc_chain_complete(atchan, atc_first_active(atchan));
/* advance work */
spin_lock_irqsave(&atchan->lock, flags);
atc_dostart(atchan, atc_first_active(atchan));
spin_unlock_irqrestore(&atchan->lock, flags);
}
/**
* atc_handle_error - handle errors reported by DMA controller
* @atchan: channel where error occurs
*
* Called with atchan->lock held and bh disabled
*/
static void atc_handle_error(struct at_dma_chan *atchan)
{
struct at_desc *bad_desc;
struct at_desc *child;
unsigned long flags;
spin_lock_irqsave(&atchan->lock, flags);
/*
* The descriptor currently at the head of the active list is
* broked. Since we don't have any way to report errors, we'll
@ -564,6 +574,8 @@ static void atc_handle_error(struct at_dma_chan *atchan)
list_for_each_entry(child, &bad_desc->tx_list, desc_node)
atc_dump_lli(atchan, &child->lli);
spin_unlock_irqrestore(&atchan->lock, flags);
/* Pretend the descriptor completed successfully */
atc_chain_complete(atchan, bad_desc);
}
@ -571,8 +583,6 @@ static void atc_handle_error(struct at_dma_chan *atchan)
/**
* atc_handle_cyclic - at the end of a period, run callback function
* @atchan: channel used for cyclic operations
*
* Called with atchan->lock held and bh disabled
*/
static void atc_handle_cyclic(struct at_dma_chan *atchan)
{
@ -591,17 +601,14 @@ 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_irqsave(&atchan->lock, flags);
if (test_and_clear_bit(ATC_IS_ERROR, &atchan->status))
atc_handle_error(atchan);
else if (atc_chan_is_cyclic(atchan))
atc_handle_cyclic(atchan);
else
atc_advance_work(atchan);
return atc_handle_error(atchan);
spin_unlock_irqrestore(&atchan->lock, flags);
if (atc_chan_is_cyclic(atchan))
return atc_handle_cyclic(atchan);
atc_advance_work(atchan);
}
static irqreturn_t at_dma_interrupt(int irq, void *dev_id)
@ -1437,6 +1444,8 @@ static int atc_terminate_all(struct dma_chan *chan)
list_splice_init(&atchan->queue, &list);
list_splice_init(&atchan->active_list, &list);
spin_unlock_irqrestore(&atchan->lock, flags);
/* Flush all pending and queued descriptors */
list_for_each_entry_safe(desc, _desc, &list, desc_node)
atc_chain_complete(atchan, desc);
@ -1445,8 +1454,6 @@ static int atc_terminate_all(struct dma_chan *chan)
/* if channel dedicated to cyclic operations, free it */
clear_bit(ATC_IS_CYCLIC, &atchan->status);
spin_unlock_irqrestore(&atchan->lock, flags);
return 0;
}
@ -1507,7 +1514,6 @@ 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");
@ -1515,9 +1521,7 @@ static void atc_issue_pending(struct dma_chan *chan)
if (atc_chan_is_cyclic(atchan))
return;
spin_lock_irqsave(&atchan->lock, flags);
atc_advance_work(atchan);
spin_unlock_irqrestore(&atchan->lock, flags);
}
/**