Commit b02e0701 authored by Shravan Chippa's avatar Shravan Chippa Committed by Vinod Koul
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dmaengine: sf-pdma: pdma_desc memory leak fix 



Commit b2cc5c46 ("dmaengine: sf-pdma: Add multithread support for a
DMA channel") changed sf_pdma_prep_dma_memcpy() to unconditionally
allocate a new sf_pdma_desc each time it is called.

The driver previously recycled descs, by checking the in_use flag, only
allocating additional descs if the existing one was in use. This logic
was removed in commit b2cc5c46 ("dmaengine: sf-pdma: Add multithread
support for a DMA channel"), but sf_pdma_free_desc() was not changed to
handle the new behaviour.

As a result, each time sf_pdma_prep_dma_memcpy() is called, the previous
descriptor is leaked, over time leading to memory starvation:

  unreferenced object 0xffffffe008447300 (size 192):
  comm "irq/39-mchp_dsc", pid 343, jiffies 4294906910 (age 981.200s)
  hex dump (first 32 bytes):
    00 00 00 ff 00 00 00 00 b8 c1 00 00 00 00 00 00  ................
    00 00 70 08 10 00 00 00 00 00 00 c0 00 00 00 00  ..p.............
  backtrace:
    [<00000000064a04f4>] kmemleak_alloc+0x1e/0x28
    [<00000000018927a7>] kmem_cache_alloc+0x11e/0x178
    [<000000002aea8d16>] sf_pdma_prep_dma_memcpy+0x40/0x112

Add the missing kfree() to sf_pdma_free_desc(), and remove the redundant
in_use flag.

Fixes: b2cc5c46 ("dmaengine: sf-pdma: Add multithread support for a DMA channel")
Signed-off-by: default avatarShravan Chippa <shravan.chippa@microchip.com>
Reviewed-by: default avatarConor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230120100623.3530634-1-shravan.chippa@microchip.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent a1beaa50

drivers/dma/sf-pdma/sf-pdma.c

+1 −2
Original line number Diff line number Diff line
@@ -96,7 +96,6 @@ sf_pdma_prep_dma_memcpy(struct dma_chan *dchan, dma_addr_t dest, dma_addr_t src, 
	if (!desc)

		return NULL;



	desc->in_use = true;

	desc->dirn = DMA_MEM_TO_MEM;

	desc->async_tx = vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
@@ -290,7 +289,7 @@ static void sf_pdma_free_desc(struct virt_dma_desc *vdesc) 
	struct sf_pdma_desc *desc;



	desc = to_sf_pdma_desc(vdesc);

	desc->in_use = false;

	kfree(desc);

}



static void sf_pdma_donebh_tasklet(struct tasklet_struct *t)

drivers/dma/sf-pdma/sf-pdma.h

+0 −1
Original line number Diff line number Diff line
@@ -78,7 +78,6 @@ struct sf_pdma_desc { 
	u64				src_addr;

	struct virt_dma_desc		vdesc;

	struct sf_pdma_chan		*chan;

	bool				in_use;

	enum dma_transfer_direction	dirn;

	struct dma_async_tx_descriptor *async_tx;

};