linux-kernel - RE: [PATCH v2] usb: dwc2: fix a devres leak in hw

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Message-ID: <BYAPR12MB33992472023C4D6BB4127B0CA7849@BYAPR12MB3399.namprd12.prod.outlook.com>
Date:   Fri, 24 Mar 2023 05:07:51 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Fabrice Gasnier <fabrice.gasnier@...s.st.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "maz@...nel.org" <maz@...nel.org>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "amelie.delaunay@...s.st.com" <amelie.delaunay@...s.st.com>,
        "alexandre.torgue@...s.st.com" <alexandre.torgue@...s.st.com>
Subject: RE: [PATCH v2] usb: dwc2: fix a devres leak in hw_enable upon suspend
 resume

Hi Fabrice,

>On 3/16/2023 12:41 PM, Fabrice Gasnier <fabrice.gasnier@...s.st.com> wrote:
>From: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
>Sent: Thursday, March 16, 2023 12:41 PM
>To: Minas Harutyunyan <hminas@...opsys.com>; gregkh@...uxfoundation.org;
>maz@...nel.org; m.szyprowski@...sung.com
>Cc: linux-usb@...r.kernel.org; linux-kernel@...r.kernel.org; linux-stm32@st-
>md-mailman.stormreply.com; amelie.delaunay@...s.st.com;
>alexandre.torgue@...s.st.com; fabrice.gasnier@...s.st.com
>Subject: [PATCH v2] usb: dwc2: fix a devres leak in hw_enable upon suspend
>resume
>
>Each time the platform goes to low power, PM suspend / resume routines
>call: __dwc2_lowlevel_hw_enable -> devm_add_action_or_reset().
>This adds a new devres each time.
>This may also happen at runtime, as dwc2_lowlevel_hw_enable() can be called
>from udc_start().
>
>This can be seen with tracing:
>- echo 1 > /sys/kernel/debug/tracing/events/dev/devres_log/enable
>- go to low power
>- cat /sys/kernel/debug/tracing/trace
>
>A new "ADD" entry is found upon each low power cycle:
>... devres_log: 49000000.usb-otg ADD 82a13bba devm_action_release (8 bytes)
>... devres_log: 49000000.usb-otg ADD 49889daf devm_action_release (8 bytes)
>...
>
>A second issue is addressed here:
>- regulator_bulk_enable() is called upon each PM cycle (suspend/resume).
>- regulator_bulk_disable() never gets called.
>
>So the reference count for these regulators constantly increase, by one upon
>each low power cycle, due to missing regulator_bulk_disable() call in
>__dwc2_lowlevel_hw_disable().
>
>The original fix that introduced the devm_add_action_or_reset() call, fixed
>an issue during probe, that happens due to other errors in
>dwc2_driver_probe() -> dwc2_core_reset(). Then the probe fails without
>disabling regulators, when dr_mode == USB_DR_MODE_PERIPHERAL.
>
>Rather fix the error path: disable all the low level hardware in the error
>path, by using the "hsotg->ll_hw_enabled" flag. Checking dr_mode has been
>introduced to avoid a dual call to dwc2_lowlevel_hw_disable().
>"ll_hw_enabled" should achieve the same (and is used currently in the
>remove() routine).
>
>Fixes: 54c196060510 ("usb: dwc2: Always disable regulators on driver
>teardown")
>Fixes: 33a06f1300a7 ("usb: dwc2: Fix error path in gadget registration")
>Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>

Reviewed-by: Quentin Schulz <quentin.schulz@...obroma-systems.com>
Tested-by: Quentin Schulz <quentin.schulz@...obroma-systems.com>
Acked-by: Minas Harutyunyan <hminas@...opsys.com>

>---
>Changes in v2: commit message updated to remove useless tags
>---
> drivers/usb/dwc2/platform.c | 16 ++--------------
> 1 file changed, 2 insertions(+), 14 deletions(-)
>
>diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c index
>262c13b6362a..d1589ba7d322 100644
>--- a/drivers/usb/dwc2/platform.c
>+++ b/drivers/usb/dwc2/platform.c
>@@ -91,13 +91,6 @@ static int dwc2_get_dr_mode(struct dwc2_hsotg *hsotg)
> 	return 0;
> }
>
>-static void __dwc2_disable_regulators(void *data) -{
>-	struct dwc2_hsotg *hsotg = data;
>-
>-	regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies), hsotg->supplies);
>-}
>-
> static int __dwc2_lowlevel_hw_enable(struct dwc2_hsotg *hsotg)  {
> 	struct platform_device *pdev = to_platform_device(hsotg->dev); @@ -
>108,11 +101,6 @@ static int __dwc2_lowlevel_hw_enable(struct dwc2_hsotg
>*hsotg)
> 	if (ret)
> 		return ret;
>
>-	ret = devm_add_action_or_reset(&pdev->dev,
>-				       __dwc2_disable_regulators, hsotg);
>-	if (ret)
>-		return ret;
>-
> 	if (hsotg->clk) {
> 		ret = clk_prepare_enable(hsotg->clk);
> 		if (ret)
>@@ -168,7 +156,7 @@ static int __dwc2_lowlevel_hw_disable(struct dwc2_hsotg
>*hsotg)
> 	if (hsotg->clk)
> 		clk_disable_unprepare(hsotg->clk);
>
>-	return 0;
>+	return regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies),
>+hsotg->supplies);
> }
>
> /**
>@@ -607,7 +595,7 @@ static int dwc2_driver_probe(struct platform_device
>*dev)
> 	if (hsotg->params.activate_stm_id_vb_detection)
> 		regulator_disable(hsotg->usb33d);
> error:
>-	if (hsotg->dr_mode != USB_DR_MODE_PERIPHERAL)
>+	if (hsotg->ll_hw_enabled)
> 		dwc2_lowlevel_hw_disable(hsotg);
> 	return retval;
> }
>--
>2.25.1