Commit 7953446d authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

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

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: default avatarJakub Kicinski <kuba@kernel.org>
parents e2142ef2 da875fa5

drivers/net/ethernet/freescale/fec_main.c

+5 −7
Original line number Diff line number Diff line
@@ -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;

include/linux/pm_runtime.h

+21 −0
Original line number Diff line number Diff line
@@ -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.

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