* [PATCH v2] usb: dwc3: gadget: don't rely on jiffies while holding spinlock
@ 2016-08-23 11:48 Nicolas Saenz Julienne
0 siblings, 0 replies; 2+ messages in thread
From: Nicolas Saenz Julienne @ 2016-08-23 11:48 UTC (permalink / raw)
To: balbi; +Cc: gregkh, linux-usb, linux-kernel
__dwc3_gadget_wakeup() is called while holding a spinlock, then depends on
jiffies in order to timeout while polling the USB core for a link state
update. In the case the wakeup failed, the timeout will never happen and
will also cause the cpu to stall until rcu_preempt kicks in.
This switches to a "decrement variable and wait" timeout scheme.
Signed-off-by: Nicolas Saenz Julienne <nicolassaenzj@gmail.com>
---
v2. removed udelay() from while loop
note: resubmitting since earlier patch had errata on e-mail address
drivers/usb/dwc3/gadget.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 1f5597e..122e64d 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1433,7 +1433,7 @@ static int dwc3_gadget_get_frame(struct usb_gadget *g)
static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
{
- unsigned long timeout;
+ int retries;
int ret;
u32 reg;
@@ -1484,9 +1484,9 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
}
/* poll until Link State changes to ON */
- timeout = jiffies + msecs_to_jiffies(100);
+ retries = 20000;
- while (!time_after(jiffies, timeout)) {
+ while (retries--) {
reg = dwc3_readl(dwc->regs, DWC3_DSTS);
/* in HS, means ON */
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH v2] usb: dwc3: gadget: don't rely on jiffies while holding spinlock
@ 2016-08-16 9:22 Nicolas Saenz Julienne
0 siblings, 0 replies; 2+ messages in thread
From: Nicolas Saenz Julienne @ 2016-08-16 9:22 UTC (permalink / raw)
To: balbi; +Cc: gregkh, linux-usb, linux-kernel, Nicolas Saenz Julienne
From: Nicolas Saenz Julienne <nicolassaenzj@gmeil.com>
__dwc3_gadget_wakeup() is called while holding a spinlock, then depends on
jiffies in order to timeout while polling the USB core for a link state
update. In the case the wakeup failed, the timeout will never happen and
will also cause the cpu to stall until rcu_preempt kicks in.
This switches to a "decrement variable and wait" timeout scheme.
Signed-off-by: Nicolas Saenz Julienne <nicolassaenzj@gmail.com>
---
v2. removed udelay()
drivers/usb/dwc3/gadget.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 8f8c215..c9451c2 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1433,7 +1433,7 @@ static int dwc3_gadget_get_frame(struct usb_gadget *g)
static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
{
- unsigned long timeout;
+ int retries;
int ret;
u32 reg;
@@ -1484,9 +1484,9 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
}
/* poll until Link State changes to ON */
- timeout = jiffies + msecs_to_jiffies(100);
+ retries = 20000;
- while (!time_after(jiffies, timeout)) {
+ while (retries--) {
reg = dwc3_readl(dwc->regs, DWC3_DSTS);
/* in HS, means ON */
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
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