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Merge branch 'fix-usage-counter-leak-by-adding-a-general-sync-ops'

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Zhang Qilong says:

====================
Fix usage counter leak by adding a general sync ops

In many case, we need to check return value of pm_runtime_get_sync,
but it brings a trouble to the usage counter processing. Many callers
forget to decrease the usage counter when it failed, which could
resulted in reference leak. It has been discussed a lot[0][1]. So we
add a function to deal with the usage counter for better coding and
view. Then, we replace pm_runtime_resume_and_get with it in fec_main.c
to avoid it.

[0] https://lkml.org/lkml/2020/6/14/88
[1] https://patchwork.ozlabs.org/project/linux-tegra/list/?series=178139
====================

Link: https://lore.kernel.org/r/20201110092933.3342784-1-zhangqilong3@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2020-11-16 09:37:13 -08:00
commit 7953446d66
2 changed files with 26 additions and 7 deletions
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12
drivers/net/ethernet/freescale/fec_main.c
View File

@ -1808,7 +1808,7 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
int ret = 0, frame_start, frame_addr, frame_op;
bool is_c45 = !!(regnum & MII_ADDR_C45);
ret = pm_runtime_get_sync(dev);
ret = pm_runtime_resume_and_get(dev);
if (ret < 0)
return ret;
@ -1867,11 +1867,9 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
int ret, frame_start, frame_addr;
bool is_c45 = !!(regnum & MII_ADDR_C45);
ret = pm_runtime_get_sync(dev);
ret = pm_runtime_resume_and_get(dev);
if (ret < 0)
return ret;
else
ret = 0;
if (is_c45) {
frame_start = FEC_MMFR_ST_C45;
@ -2275,7 +2273,7 @@ static void fec_enet_get_regs(struct net_device *ndev,
u32 i, off;
int ret;
ret = pm_runtime_get_sync(dev);
ret = pm_runtime_resume_and_get(dev);
if (ret < 0)
return;
@ -2976,7 +2974,7 @@ fec_enet_open(struct net_device *ndev)
int ret;
bool reset_again;
ret = pm_runtime_get_sync(&fep->pdev->dev);
ret = pm_runtime_resume_and_get(&fep->pdev->dev);
if (ret < 0)
return ret;
@ -3770,7 +3768,7 @@ fec_drv_remove(struct platform_device *pdev)
struct device_node *np = pdev->dev.of_node;
int ret;
ret = pm_runtime_get_sync(&pdev->dev);
ret = pm_runtime_resume_and_get(&pdev->dev);
if (ret < 0)
return ret;

21
include/linux/pm_runtime.h
View File

@ -386,6 +386,27 @@ static inline int pm_runtime_get_sync(struct device *dev)
return __pm_runtime_resume(dev, RPM_GET_PUT);
}
/**
* pm_runtime_resume_and_get - Bump up usage counter of a device and resume it.
* @dev: Target device.
*
* Resume @dev synchronously and if that is successful, increment its runtime
* PM usage counter. Return 0 if the runtime PM usage counter of @dev has been
* incremented or a negative error code otherwise.
*/
static inline int pm_runtime_resume_and_get(struct device *dev)
{
int ret;
ret = __pm_runtime_resume(dev, RPM_GET_PUT);
if (ret < 0) {
pm_runtime_put_noidle(dev);
return ret;
}
return 0;
}
/**
* pm_runtime_put - Drop device usage counter and queue up "idle check" if 0.
* @dev: Target device.