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FAILED: patch "[PATCH] dmaengine: at_hdmac: Fix concurrency over descriptor" failed to apply to 5.4-stable tree

PATCH [email protected] 1 participant 1 message Nov 14, 2022

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Stable branch dmaengine Microchip AT91 DMA drivers
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The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Possible dependencies:

06988949df8c ("dmaengine: at_hdmac: Fix concurrency over descriptor") 078a6506141a ("dmaengine: at_hdmac: Fix deadlocks")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 06988949df8c3007ad82036d3606d8ae72ed9000 Mon Sep 17 00:00:00 2001
From: Tudor Ambarus <[email protected]>
Date: Tue, 25 Oct 2022 12:02:42 +0300
Subject: [PATCH] dmaengine: at_hdmac: Fix concurrency over descriptor

The descriptor was added to the free_list before calling the callback, which could result in reissuing of the same descriptor and calling of a single callback for both. Move the decriptor to the free list after the callback is invoked.

Fixes dc78baa2b90b ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller")
Reported-by Peter Rosin <[email protected]>
Signed-off-by Tudor Ambarus <[email protected]>
Cc [email protected]
Link https://lore.kernel.org/lkml/[email protected]/ open here
Acked-by Nicolas Ferre <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Vinod Koul <[email protected]>
drivers/dma/at_hdmac.c +9 -5
index f1e6fa6af6c2..2012ecc57826 100644
@@ -469,11 +469,8 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
 		desc->memset_buffer = false;
 	}
 
-	/* move children to free_list */
-	list_splice_init(&desc->tx_list, &atchan->free_list);
-	/* move myself to free_list */
-	list_move(&desc->desc_node, &atchan->free_list);
-
+	/* Remove transfer node from the active list. */
+	list_del_init(&desc->desc_node);
 	spin_unlock_irqrestore(&atchan->lock, flags);
 
 	dma_descriptor_unmap(txd);

@@ -483,6 +480,13 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
 		dmaengine_desc_get_callback_invoke(txd, NULL);
 
 	dma_run_dependencies(txd);
+
+	spin_lock_irqsave(&atchan->lock, flags);
+	/* move children to free_list */
+	list_splice_init(&desc->tx_list, &atchan->free_list);
+	/* add myself to free_list */
+	list_add(&desc->desc_node, &atchan->free_list);
+	spin_unlock_irqrestore(&atchan->lock, flags);
 }
 
 /**