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dmaengine: at_hdmac: Fix concurrency problems by removing atc_complete_all()

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commit c6babed879fbe82796a601bf097649e07382db46 upstream.

atc_complete_all() had concurrency bugs, thus remove it:
1/ atc_complete_all() in its entirety was buggy, as when the atchan->queue
list (the one that contains descriptors that are not yet issued to the
hardware) contained descriptors, it fired just the first from the
atchan->queue, but moved all the desc from atchan->queue to
atchan->active_list and considered them all as fired. This could result in
calling the completion of a descriptor that was not yet issued to the
hardware.
2/ when in tasklet at atc_advance_work() time, atchan->active_list was
queried without holding the lock of the chan. This can result in
atchan->active_list concurrency problems between the tasklet and
issue_pending().

Fixes: dc78baa2b9 ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller")
Reported-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com
Link: https://lore.kernel.org/r/20221025090306.297886-8-tudor.ambarus@microchip.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tudor Ambarus 2022-10-25 12:02:41 +03:00 committed by Greg Kroah-Hartman
parent 9b69060a72
commit 1582cc3b48
1 changed files with 4 additions and 45 deletions
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49
drivers/dma/at_hdmac.c
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@ -466,42 +466,6 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
dma_run_dependencies(txd);
}
/**
* atc_complete_all - finish work for all transactions
* @atchan: channel to complete transactions for
*
* Eventually submit queued descriptors if any
*
* Assume channel is idle while calling this function
* Called with atchan->lock held and bh disabled
*/
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.
*/
if (!list_empty(&atchan->queue))
atc_dostart(atchan, atc_first_queued(atchan));
/* empty active_list now it is completed */
list_splice_init(&atchan->active_list, &list);
/* 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);
}
/**
* atc_advance_work - at the end of a transaction, move forward
* @atchan: channel where the transaction ended
@ -509,25 +473,20 @@ static void atc_complete_all(struct at_dma_chan *atchan)
static void atc_advance_work(struct at_dma_chan *atchan)
{
unsigned long flags;
int ret;
dev_vdbg(chan2dev(&atchan->chan_common), "advance_work\n");
spin_lock_irqsave(&atchan->lock, flags);
ret = atc_chan_is_enabled(atchan);
if (atc_chan_is_enabled(atchan) || list_empty(&atchan->active_list))
return spin_unlock_irqrestore(&atchan->lock, flags);
spin_unlock_irqrestore(&atchan->lock, flags);
if (ret)
return;
if (list_empty(&atchan->active_list) ||
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));
if (!list_empty(&atchan->active_list))
atc_dostart(atchan, atc_first_active(atchan));
spin_unlock_irqrestore(&atchan->lock, flags);
}