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author | Tudor Ambarus <tudor.ambarus@microchip.com> | 2022-10-25 12:02:41 +0300 |
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committer | Vinod Koul <vkoul@kernel.org> | 2022-11-08 10:43:57 +0530 |
commit | c6babed879fbe82796a601bf097649e07382db46 (patch) | |
tree | c4f772beb0b06184e9caa6444714a3fc90d4e9af /drivers/dma | |
parent | 6e5ad28d16f082efeae3d0bd2e31f24bed218019 (diff) | |
download | linux-stable-c6babed879fbe82796a601bf097649e07382db46.tar.gz linux-stable-c6babed879fbe82796a601bf097649e07382db46.tar.bz2 linux-stable-c6babed879fbe82796a601bf097649e07382db46.zip |
dmaengine: at_hdmac: Fix concurrency problems by removing atc_complete_all()
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: dc78baa2b90b ("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>
Diffstat (limited to 'drivers/dma')
-rw-r--r-- | drivers/dma/at_hdmac.c | 49 |
1 files changed, 4 insertions, 45 deletions
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index deb4c6027436..f1e6fa6af6c2 100644 --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -486,67 +486,26 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc) } /** - * 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 */ 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); } |