2020-11-27 09:45:20

by Qinglang Miao

Subject: [PATCH] dmaengine: tegra-apb: fix reference leak in tegra_dma_issue_pending and tegra_dma_synchronize

pm_runtime_get_sync will increment pm usage counter even it
failed. Forgetting to putting operation will result in a
reference leak here.

A new function pm_runtime_resume_and_get is introduced in
[0] to keep usage counter balanced. So We fix the reference
leak by replacing it with new funtion.

[0] dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")

Fixes: 84a3f375eea9 ("dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer")
Fixes: 664475cffb8c ("dmaengine: tegra-apb: Ensure that clock is enabled during of DMA synchronization")
Reported-by: Hulk Robot <[email protected]>
Signed-off-by: Qinglang Miao <[email protected]>
---
drivers/dma/tegra20-apb-dma.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 71827d9b0..b7260749e 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -723,7 +723,7 @@ static void tegra_dma_issue_pending(struct dma_chan *dc)
goto end;
}
if (!tdc->busy) {
- err = pm_runtime_get_sync(tdc->tdma->dev);
+ err = pm_runtime_resume_and_get(tdc->tdma->dev);
if (err < 0) {
dev_err(tdc2dev(tdc), "Failed to enable DMA\n");
goto end;
@@ -818,7 +818,7 @@ static void tegra_dma_synchronize(struct dma_chan *dc)
struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
int err;

- err = pm_runtime_get_sync(tdc->tdma->dev);
+ err = pm_runtime_resume_and_get(tdc->tdma->dev);
if (err < 0) {
dev_err(tdc2dev(tdc), "Failed to synchronize DMA: %d\n", err);
return;
--
2.23.0

2020-11-30 11:15:32

by Jon Hunter

Subject: Re: [PATCH] dmaengine: tegra-apb: fix reference leak in tegra_dma_issue_pending and tegra_dma_synchronize

On 27/11/2020 09:44, Qinglang Miao wrote:
> pm_runtime_get_sync will increment pm usage counter even it
> failed. Forgetting to putting operation will result in a
> reference leak here.
>
> A new function pm_runtime_resume_and_get is introduced in
> [0] to keep usage counter balanced. So We fix the reference
> leak by replacing it with new funtion.
>
> [0] dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
>
> Fixes: 84a3f375eea9 ("dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer")
> Fixes: 664475cffb8c ("dmaengine: tegra-apb: Ensure that clock is enabled during of DMA synchronization")
> Reported-by: Hulk Robot <[email protected]>
> Signed-off-by: Qinglang Miao <[email protected]>
> ---
> drivers/dma/tegra20-apb-dma.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index 71827d9b0..b7260749e 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -723,7 +723,7 @@ static void tegra_dma_issue_pending(struct dma_chan *dc)
> goto end;
> }
> if (!tdc->busy) {
> - err = pm_runtime_get_sync(tdc->tdma->dev);
> + err = pm_runtime_resume_and_get(tdc->tdma->dev);
> if (err < 0) {
> dev_err(tdc2dev(tdc), "Failed to enable DMA\n");
> goto end;
> @@ -818,7 +818,7 @@ static void tegra_dma_synchronize(struct dma_chan *dc)
> struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> int err;
>
> - err = pm_runtime_get_sync(tdc->tdma->dev);
> + err = pm_runtime_resume_and_get(tdc->tdma->dev);
> if (err < 0) {
> dev_err(tdc2dev(tdc), "Failed to synchronize DMA: %d\n", err);
> return;


Reviewed-by: Jon Hunter <[email protected]>

Cheers
Jon

--
nvpublic