linux-kernel - [PATCH] mfd: omap-usb-tll: Don't hold lock during pm_runtime_get/put

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Date:	Wed, 18 Dec 2013 15:31:49 +0530
From:	Roger Quadros <rogerq@...com>
To:	<lee.jones@...aro.org>, <sameo@...ux.intel.com>
CC:	<balbi@...com>, <linux-kernel@...r.kernel.org>,
	<linux-usb@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	Roger Quadros <rogerq@...com>, <stable@...r.kernel.org>
Subject: [PATCH] mfd: omap-usb-tll: Don't hold lock during pm_runtime_get/put_sync()

pm_runtime_get/put_sync() can sleep so don't hold spinlock while
calling them.

This patch prevents a BUG() when CONFIG_DEBUG_ATOMIC_SLEEP is enabled.
Bug is present in Kernel versions v3.9 onwards.

Reported-by: Tomi Valkeinen <tomi.valkeinen@...com>
Signed-off-by: Roger Quadros <rogerq@...com>
Tested-by: Tomi Valkeinen <tomi.valkeinen@...com>
Cc: <stable@...r.kernel.org> # 3.9+
---
 drivers/mfd/omap-usb-tll.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
index 0d946ae1..248004c 100644
--- a/drivers/mfd/omap-usb-tll.c
+++ b/drivers/mfd/omap-usb-tll.c
@@ -346,7 +346,9 @@ int omap_tll_init(struct usbhs_omap_platform_data *pdata)
 	for (i = 0; i < tll->nch; i++)
 		needs_tll |= omap_usb_mode_needs_tll(pdata->port_mode[i]);
 
+	spin_unlock(&tll_lock);
 	pm_runtime_get_sync(tll_dev);
+	spin_lock(&tll_lock);
 
 	if (needs_tll) {
 		void __iomem *base = tll->base;
@@ -398,9 +400,8 @@ int omap_tll_init(struct usbhs_omap_platform_data *pdata)
 		}
 	}
 
-	pm_runtime_put_sync(tll_dev);
-
 	spin_unlock(&tll_lock);
+	pm_runtime_put_sync(tll_dev);
 
 	return 0;
 }
@@ -420,7 +421,9 @@ int omap_tll_enable(struct usbhs_omap_platform_data *pdata)
 
 	tll = dev_get_drvdata(tll_dev);
 
+	spin_unlock(&tll_lock);
 	pm_runtime_get_sync(tll_dev);
+	spin_lock(&tll_lock);
 
 	for (i = 0; i < tll->nch; i++) {
 		if (omap_usb_mode_needs_tll(pdata->port_mode[i])) {
@@ -438,7 +441,6 @@ int omap_tll_enable(struct usbhs_omap_platform_data *pdata)
 	}
 
 	spin_unlock(&tll_lock);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(omap_tll_enable);
@@ -464,9 +466,8 @@ int omap_tll_disable(struct usbhs_omap_platform_data *pdata)
 		}
 	}
 
-	pm_runtime_put_sync(tll_dev);
-
 	spin_unlock(&tll_lock);
+	pm_runtime_put_sync(tll_dev);
 
 	return 0;
 }
-- 
1.8.3.2

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