[PATCH 2/4] phy: qcom: qmp-usbc: Fix possible NULL-deref on early runtime suspend

[Loic Poulain]

There is a small window where the runtime suspend callback may run
after pm_runtime_enable() and before pm_runtime_forbid(). In this
case, a crash occurs because runtime suspend/resume dereferences
qmp->phy pointer, which is not yet initialized:
    `if (!qmp->phy->init_count) {`

Use qmp->usb_init_count instead of qmp->phy->init_count to avoid
depending on the possibly uninitialized phy pointer.

Also reorder pm_runtime_enable() and pm_runtime_forbid() to prevent
the window where an unnecessary runtime suspend can occur.

Fixes: 19281571a4d5 ("phy: qcom: qmp-usb: split USB-C PHY driver")
Signed-off-by: Loic Poulain <loic.poulain at oss.qualcomm.com>
---
 drivers/phy/qualcomm/phy-qcom-qmp-usbc.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c b/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
index 5e7fcb26744a..05717ca85c5b 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-usbc.c
@@ -690,7 +690,7 @@ static int __maybe_unused qmp_usbc_runtime_suspend(struct device *dev)
 
 	dev_vdbg(dev, "Suspending QMP phy, mode:%d\n", qmp->mode);
 
-	if (!qmp->phy->init_count) {
+	if (!qmp->usb_init_count) {
 		dev_vdbg(dev, "PHY not initialized, bailing out\n");
 		return 0;
 	}
@@ -710,7 +710,7 @@ static int __maybe_unused qmp_usbc_runtime_resume(struct device *dev)
 
 	dev_vdbg(dev, "Resuming QMP phy, mode:%d\n", qmp->mode);
 
-	if (!qmp->phy->init_count) {
+	if (!qmp->usb_init_count) {
 		dev_vdbg(dev, "PHY not initialized, bailing out\n");
 		return 0;
 	}
@@ -1083,15 +1083,15 @@ static int qmp_usbc_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_node_put;
 
+	/*
+	 * Enable runtime PM support, but forbid it by default.
+	 * Users can allow it again via the power/control attribute in sysfs.
+	 */
 	pm_runtime_set_active(dev);
+	pm_runtime_forbid(dev);
 	ret = devm_pm_runtime_enable(dev);
 	if (ret)
 		goto err_node_put;
-	/*
-	 * Prevent runtime pm from being ON by default. Users can enable
-	 * it using power/control in sysfs.
-	 */
-	pm_runtime_forbid(dev);
 
 	ret = phy_pipe_clk_register(qmp, np);
 	if (ret)
-- 
2.34.1