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* [PATCH 2/2] usb: isp1760: Replace mdelay with msleep in isp1760_stop
@ 2018-04-10  7:37 ` Jia-Ju Bai
  0 siblings, 0 replies; 2+ messages in thread
From: Jia-Ju Bai @ 2018-04-10  7:37 UTC (permalink / raw)
  To: gregkh; +Cc: linux-usb, linux-kernel, Jia-Ju Bai

isp1760_stop() is never called in atomic context.

The call chain ending up at isp1760_stop() is:
[1] isp1760_stop() <- isp1760_shutdown()

isp1760_shutdown() is set as ".shutdown" in struct hc_driver.
isp1760_stop() is also set as ".stop" in hc_driver.
These functions are not called in atomic context.

Despite never getting called from atomic context, isp1760_stop()
calls mdelay() to busily wait.
This is not necessary and can be replaced with msleep() to
avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 drivers/usb/isp1760/isp1760-hcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/isp1760/isp1760-hcd.c b/drivers/usb/isp1760/isp1760-hcd.c
index 8e59e0c..5599310 100644
--- a/drivers/usb/isp1760/isp1760-hcd.c
+++ b/drivers/usb/isp1760/isp1760-hcd.c
@@ -2090,7 +2090,7 @@ static void isp1760_stop(struct usb_hcd *hcd)
 
 	isp1760_hub_control(hcd, ClearPortFeature, USB_PORT_FEAT_POWER,	1,
 			NULL, 0);
-	mdelay(20);
+	msleep(20);
 
 	spin_lock_irq(&priv->lock);
 	ehci_reset(hcd);
-- 
1.9.1


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* [2/2] usb: isp1760: Replace mdelay with msleep in isp1760_stop
@ 2018-04-10  7:37 ` Jia-Ju Bai
  0 siblings, 0 replies; 2+ messages in thread
From: Jia-Ju Bai @ 2018-04-10  7:37 UTC (permalink / raw)
  To: gregkh; +Cc: linux-usb, linux-kernel, Jia-Ju Bai

isp1760_stop() is never called in atomic context.

The call chain ending up at isp1760_stop() is:
[1] isp1760_stop() <- isp1760_shutdown()

isp1760_shutdown() is set as ".shutdown" in struct hc_driver.
isp1760_stop() is also set as ".stop" in hc_driver.
These functions are not called in atomic context.

Despite never getting called from atomic context, isp1760_stop()
calls mdelay() to busily wait.
This is not necessary and can be replaced with msleep() to
avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 drivers/usb/isp1760/isp1760-hcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/isp1760/isp1760-hcd.c b/drivers/usb/isp1760/isp1760-hcd.c
index 8e59e0c..5599310 100644
--- a/drivers/usb/isp1760/isp1760-hcd.c
+++ b/drivers/usb/isp1760/isp1760-hcd.c
@@ -2090,7 +2090,7 @@ static void isp1760_stop(struct usb_hcd *hcd)
 
 	isp1760_hub_control(hcd, ClearPortFeature, USB_PORT_FEAT_POWER,	1,
 			NULL, 0);
-	mdelay(20);
+	msleep(20);
 
 	spin_lock_irq(&priv->lock);
 	ehci_reset(hcd);

^ permalink raw reply related	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2018-04-10  7:37 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
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2018-04-10  7:37 [PATCH 2/2] usb: isp1760: Replace mdelay with msleep in isp1760_stop Jia-Ju Bai
2018-04-10  7:37 ` [2/2] " Jia-Ju Bai

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