dmaengine: virt-dma: Add missing locking
authorSascha Hauer <s.hauer@pengutronix.de>
Mon, 16 Dec 2019 10:53:21 +0000 (11:53 +0100)
committerVinod Koul <vkoul@kernel.org>
Thu, 26 Dec 2019 04:34:18 +0000 (10:04 +0530)
commit51fe9cd2bd92d95fc200385187d346e293ceefc9
treea246a3539224a5adc2cf2f899ac47f93f407acb8
parent5c8aacbbb3b706a024eefc376b1d542d59de5749
dmaengine: virt-dma: Add missing locking

Originally freeing descriptors was split into a locked and an unlocked
part. The locked part in vchan_get_all_descriptors() collected all
descriptors on a separate list_head. This was done to allow iterating
over that new list in vchan_dma_desc_free_list() without a lock held.

This became broken in 13bb26ae8850 ("dmaengine: virt-dma: don't always
free descriptor upon completion"). With this commit
vchan_dma_desc_free_list() no longer exclusively operates on the
separate list, but starts to put descriptors which can be reused back on
&vc->desc_allocated. This list operation should have been locked, but
wasn't.
In the mean time drivers started to call vchan_dma_desc_free_list() with
their lock held so that we now have the situation that
vchan_dma_desc_free_list() is called locked from some drivers and
unlocked from others.
To clean this up we have to do two things:

1. Add missing locking in vchan_dma_desc_free_list()
2. Make sure drivers call vchan_dma_desc_free_list() unlocked

This needs to be done atomically, so in this patch the locking is added
and all drivers are fixed.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Green Wan <green.wan@sifive.com>
Tested-by: Green Wan <green.wan@sifive.com>
Link: https://lore.kernel.org/r/20191216105328.15198-3-s.hauer@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>
drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
drivers/dma/mediatek/mtk-uart-apdma.c
drivers/dma/owl-dma.c
drivers/dma/s3c24xx-dma.c
drivers/dma/sf-pdma/sf-pdma.c
drivers/dma/sun4i-dma.c
drivers/dma/virt-dma.c