[PATCH V2] dmaengine: Fix client_count is countered one more incorrectly.

Koba Ko
2022-09-30T17:37:04Z

If the passed client_count is 0,
it would be incremented by balance_ref_count first
then increment one more.
This would cause client_count to 2.

cat /sys/class/dma/dma0chan*/in_use
2
2
2

Fixes: d2f4f99db3e9 ("dmaengine: Rework dma_chan_get")
Signed-off-by: Koba Ko <koba.ko@canonical.com>
Reviewed-by: Jie Hai <haijie1@huawei.com>
Test-by: Jie Hai <haijie1@huawei.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>

---
V2: Remove [3/3] on subject.
---
drivers/dma/dmaengine.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 2cfa8458b51be..78f8a9f3ad825 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -451,7 +451,8 @@ static int dma_chan_get(struct dma_chan *chan)
/* The channel is already in use, update client count */
if (chan->client_count) {
__module_get(owner);
- goto out;
+ chan->client_count++;
+ return 0;
}

if (!try_module_get(owner))
@@ -470,11 +471,11 @@ static int dma_chan_get(struct dma_chan *chan)
goto err_out;
}

+ chan->client_count++;
+
if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
balance_ref_count(chan);

-out:
- chan->client_count++;
return 0;

err_out:
--
2.25.1