| Message ID | 20200621054710.9915-1-dinghao.liu@zju.edu.cn (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v4] dmaengine: tegra210-adma: Fix runtime PM imbalance on error | expand |
On 21/06/2020 06:47, Dinghao Liu wrote: > pm_runtime_get_sync() increments the runtime PM usage counter even > when it returns an error code. Thus a pairing decrement is needed on > the error handling path to keep the counter balanced. So you have not mentioned here why you are using _noidle and not _put. Furthermore, in this patch [0] you are not using _noidle to fix the same problem in another driver. We should fix this in a consistent manner across all drivers, otherwise it leads to more confusion. Finally, Rafael mentions we should just use _put [0] and so I think we should follow his recommendation. Jon [0] https://lkml.org/lkml/2020/5/21/601
Hi Jon, More stirring in the cesspool ;-) On Tue, Jun 23, 2020 at 12:13 PM Jon Hunter <jonathanh@nvidia.com> wrote: > On 21/06/2020 06:47, Dinghao Liu wrote: > > pm_runtime_get_sync() increments the runtime PM usage counter even > > when it returns an error code. Thus a pairing decrement is needed on > > the error handling path to keep the counter balanced. > > So you have not mentioned here why you are using _noidle and not _put. > Furthermore, in this patch [0] you are not using _noidle to fix the same > problem in another driver. We should fix this in a consistent manner > across all drivers, otherwise it leads to more confusion. > > Finally, Rafael mentions we should just use _put [0] and so I think we > should follow his recommendation. > > Jon > > [0] https://lkml.org/lkml/2020/5/21/601 "_noidle() is the simplest one and it is sufficient." https://lore.kernel.org/linux-i2c/CAJZ5v0i87NGcy9+kxubScdPDyByr8ypQWcGgBFn+V-wDd69BHQ@mail.gmail.com/ You never know what additional things the other put* variants will start doing in the future... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
Hi Geert, On 23/06/2020 13:08, Geert Uytterhoeven wrote: > Hi Jon, > > More stirring in the cesspool ;-) Ha! Indeed. > On Tue, Jun 23, 2020 at 12:13 PM Jon Hunter <jonathanh@nvidia.com> wrote: >> On 21/06/2020 06:47, Dinghao Liu wrote: >>> pm_runtime_get_sync() increments the runtime PM usage counter even >>> when it returns an error code. Thus a pairing decrement is needed on >>> the error handling path to keep the counter balanced. >> >> So you have not mentioned here why you are using _noidle and not _put. >> Furthermore, in this patch [0] you are not using _noidle to fix the same >> problem in another driver. We should fix this in a consistent manner >> across all drivers, otherwise it leads to more confusion. >> >> Finally, Rafael mentions we should just use _put [0] and so I think we >> should follow his recommendation. >> >> Jon >> >> [0] https://lkml.org/lkml/2020/5/21/601 > > "_noidle() is the simplest one and it is sufficient." > https://lore.kernel.org/linux-i2c/CAJZ5v0i87NGcy9+kxubScdPDyByr8ypQWcGgBFn+V-wDd69BHQ@mail.gmail.com/ Good to know. This detail should be spelled out in the changelog so that it is clear why we are using _noidle and not _put. I did take a look and it did seem to handle the usage_count OK, but I was concerned if there could be something else in the _put path that may get missed. Anyway, I am fine with the change, but with an updated changelog on why _noidle is being used. > You never know what additional things the other put* variants > will start doing in the future... Hopefully not, as that would be a breakage of the API itself. From what Rafael said that all _put calls should work and if at some point in the future they don't, then that seems like a regression. Jon
diff --git a/drivers/dma/tegra210-adma.c b/drivers/dma/tegra210-adma.c index db58d7e4f9fe..c5fa2ef74abc 100644 --- a/drivers/dma/tegra210-adma.c +++ b/drivers/dma/tegra210-adma.c @@ -658,6 +658,7 @@ static int tegra_adma_alloc_chan_resources(struct dma_chan *dc) ret = pm_runtime_get_sync(tdc2dev(tdc)); if (ret < 0) { + pm_runtime_put_noidle(tdc2dev(tdc)); free_irq(tdc->irq, tdc); return ret; } @@ -869,8 +870,10 @@ static int tegra_adma_probe(struct platform_device *pdev) pm_runtime_enable(&pdev->dev); ret = pm_runtime_get_sync(&pdev->dev); - if (ret < 0) + if (ret < 0) { + pm_runtime_put_noidle(&pdev->dev); goto rpm_disable; + } ret = tegra_adma_init(tdma); if (ret)
pm_runtime_get_sync() increments the runtime PM usage counter even when it returns an error code. Thus a pairing decrement is needed on the error handling path to keep the counter balanced. Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn> --- v2: - Merge two patches that fix runtime PM imbalance in tegra_adma_probe() and tegra_adma_alloc_chan_resources() respectively. v3: - Use pm_runtime_put_noidle() instead of pm_runtime_put_sync() in tegra_adma_alloc_chan_resources(). v4: - Use pm_runtime_put_noidle() instead of pm_runtime_put_sync() in tegra_adma_probe(). --- drivers/dma/tegra210-adma.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)