* [PATCH 0/3] watchdog: at91sam9_wdt: various fixes and improvements
@ 2013-11-03 17:52 ` Boris BREZILLON
0 siblings, 0 replies; 14+ messages in thread
From: Boris BREZILLON @ 2013-11-03 17:52 UTC (permalink / raw)
To: linux-arm-kernel
Hello,
This patch series fix the secs_to_ticks macro in case 0 is passed as an
argument.
It also rework the heartbeat calculation to increase the security margin of the
watchdog reset timer, and use the min_heartbeat value instead of the calculated
heartbeat value for the first watchdog reset (to avoid spurious watchdog
reset).
Best Regards,
Boris
Boris BREZILLON (3):
watchdog: at91sam9_wdt: fix secs_to_ticks
watchdog: at91sam9_wdt: avoid spurious watchdog reset during init
watchdog: at91sam9_wdt: increase security margin on watchdog counter
reset
drivers/watchdog/at91sam9_wdt.c | 38 +++++++++++++++++++++++++++-----------
1 file changed, 27 insertions(+), 11 deletions(-)
--
1.7.9.5
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH 1/3] watchdog: at91sam9_wdt: fix secs_to_ticks
2013-11-03 17:52 ` Boris BREZILLON
@ 2013-11-03 17:52 ` Boris BREZILLON
-1 siblings, 0 replies; 14+ messages in thread
From: Boris BREZILLON @ 2013-11-03 17:52 UTC (permalink / raw)
To: Wim Van Sebroeck
Cc: Fabio Porcedda, Nicolas Ferre, Guenter Roeck, Yang Wenyou,
linux-kernel, linux-arm-kernel, linux-watchdog, Boris BREZILLON
Fix the secs_to_ticks macro in case 0 is passed as an argument.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
drivers/watchdog/at91sam9_wdt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index 9bd089e..65f4691 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -51,7 +51,7 @@
#define ticks_to_hz_rounddown(t) ((((t) + 1) * HZ) >> 8)
#define ticks_to_hz_roundup(t) (((((t) + 1) * HZ) + 255) >> 8)
#define ticks_to_secs(t) (((t) + 1) >> 8)
-#define secs_to_ticks(s) (((s) << 8) - 1)
+#define secs_to_ticks(s) ((s) ? (((s) << 8) - 1) : 0)
#define WDT_MR_RESET 0x3FFF2FFF
--
1.7.9.5
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH 1/3] watchdog: at91sam9_wdt: fix secs_to_ticks
@ 2013-11-03 17:52 ` Boris BREZILLON
0 siblings, 0 replies; 14+ messages in thread
From: Boris BREZILLON @ 2013-11-03 17:52 UTC (permalink / raw)
To: linux-arm-kernel
Fix the secs_to_ticks macro in case 0 is passed as an argument.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
drivers/watchdog/at91sam9_wdt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index 9bd089e..65f4691 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -51,7 +51,7 @@
#define ticks_to_hz_rounddown(t) ((((t) + 1) * HZ) >> 8)
#define ticks_to_hz_roundup(t) (((((t) + 1) * HZ) + 255) >> 8)
#define ticks_to_secs(t) (((t) + 1) >> 8)
-#define secs_to_ticks(s) (((s) << 8) - 1)
+#define secs_to_ticks(s) ((s) ? (((s) << 8) - 1) : 0)
#define WDT_MR_RESET 0x3FFF2FFF
--
1.7.9.5
^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: [PATCH 1/3] watchdog: at91sam9_wdt: fix secs_to_ticks
2013-11-03 17:52 ` Boris BREZILLON
@ 2013-11-03 18:06 ` Guenter Roeck
-1 siblings, 0 replies; 14+ messages in thread
From: Guenter Roeck @ 2013-11-03 18:06 UTC (permalink / raw)
To: Boris BREZILLON, Wim Van Sebroeck
Cc: Fabio Porcedda, Nicolas Ferre, Guenter Roeck, Yang Wenyou,
linux-kernel, linux-arm-kernel, linux-watchdog
On 11/03/2013 09:52 AM, Boris BREZILLON wrote:
> Fix the secs_to_ticks macro in case 0 is passed as an argument.
>
> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH 2/3] watchdog: at91sam9_wdt: avoid spurious watchdog reset during init
2013-11-03 17:52 ` Boris BREZILLON
@ 2013-11-03 17:52 ` Boris BREZILLON
-1 siblings, 0 replies; 14+ messages in thread
From: Boris BREZILLON @ 2013-11-03 17:52 UTC (permalink / raw)
To: Wim Van Sebroeck
Cc: Fabio Porcedda, Nicolas Ferre, Guenter Roeck, Yang Wenyou,
linux-kernel, linux-arm-kernel, linux-watchdog, Boris BREZILLON
Use the min_heartbeat value instead of the calculated heartbeat value for
the first watchdog reset to avoid spurious watchdog reset.
Resetting the watchdog counter during init might lead to a watchdog fault
reset because the watchdog counter has to be running for at least
min_heartbeat.
Resetting the watchdog counter after heartbeat might lead to a watchdog
timeout reset because the watchdog counter is running for more than
max_heartbeat time.
Using min_heartbeat instead of heartbeat does not guarantee that the
watchdog won't trigger a reset, but at least it reduces the chances to be
in such a case.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
drivers/watchdog/at91sam9_wdt.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index 65f4691..ab0c4e0 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -213,7 +213,15 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
- mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
+
+ /*
+ * Use min_heartbeat the first time to avoid spurious watchdog reset:
+ * we don't know for how long the watchdog counter is running, and
+ * - resetting it right now might trigger a watchdog fault reset
+ * - waiting for heartbeat time might lead to a watchdog timeout
+ * reset
+ */
+ mod_timer(&wdt->timer, jiffies + min_heartbeat);
/* Try to set timeout from device tree first */
if (watchdog_init_timeout(&wdt->wdd, 0, dev))
--
1.7.9.5
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH 2/3] watchdog: at91sam9_wdt: avoid spurious watchdog reset during init
@ 2013-11-03 17:52 ` Boris BREZILLON
0 siblings, 0 replies; 14+ messages in thread
From: Boris BREZILLON @ 2013-11-03 17:52 UTC (permalink / raw)
To: linux-arm-kernel
Use the min_heartbeat value instead of the calculated heartbeat value for
the first watchdog reset to avoid spurious watchdog reset.
Resetting the watchdog counter during init might lead to a watchdog fault
reset because the watchdog counter has to be running for at least
min_heartbeat.
Resetting the watchdog counter after heartbeat might lead to a watchdog
timeout reset because the watchdog counter is running for more than
max_heartbeat time.
Using min_heartbeat instead of heartbeat does not guarantee that the
watchdog won't trigger a reset, but at least it reduces the chances to be
in such a case.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
drivers/watchdog/at91sam9_wdt.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index 65f4691..ab0c4e0 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -213,7 +213,15 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
- mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
+
+ /*
+ * Use min_heartbeat the first time to avoid spurious watchdog reset:
+ * we don't know for how long the watchdog counter is running, and
+ * - resetting it right now might trigger a watchdog fault reset
+ * - waiting for heartbeat time might lead to a watchdog timeout
+ * reset
+ */
+ mod_timer(&wdt->timer, jiffies + min_heartbeat);
/* Try to set timeout from device tree first */
if (watchdog_init_timeout(&wdt->wdd, 0, dev))
--
1.7.9.5
^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: [PATCH 2/3] watchdog: at91sam9_wdt: avoid spurious watchdog reset during init
2013-11-03 17:52 ` Boris BREZILLON
@ 2013-11-03 18:09 ` Guenter Roeck
-1 siblings, 0 replies; 14+ messages in thread
From: Guenter Roeck @ 2013-11-03 18:09 UTC (permalink / raw)
To: Boris BREZILLON, Wim Van Sebroeck
Cc: Fabio Porcedda, Nicolas Ferre, Guenter Roeck, Yang Wenyou,
linux-kernel, linux-arm-kernel, linux-watchdog
On 11/03/2013 09:52 AM, Boris BREZILLON wrote:
> Use the min_heartbeat value instead of the calculated heartbeat value for
> the first watchdog reset to avoid spurious watchdog reset.
>
> Resetting the watchdog counter during init might lead to a watchdog fault
> reset because the watchdog counter has to be running for at least
> min_heartbeat.
>
> Resetting the watchdog counter after heartbeat might lead to a watchdog
> timeout reset because the watchdog counter is running for more than
> max_heartbeat time.
>
> Using min_heartbeat instead of heartbeat does not guarantee that the
> watchdog won't trigger a reset, but at least it reduces the chances to be
> in such a case.
>
> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH 2/3] watchdog: at91sam9_wdt: avoid spurious watchdog reset during init
@ 2013-11-03 18:09 ` Guenter Roeck
0 siblings, 0 replies; 14+ messages in thread
From: Guenter Roeck @ 2013-11-03 18:09 UTC (permalink / raw)
To: linux-arm-kernel
On 11/03/2013 09:52 AM, Boris BREZILLON wrote:
> Use the min_heartbeat value instead of the calculated heartbeat value for
> the first watchdog reset to avoid spurious watchdog reset.
>
> Resetting the watchdog counter during init might lead to a watchdog fault
> reset because the watchdog counter has to be running for at least
> min_heartbeat.
>
> Resetting the watchdog counter after heartbeat might lead to a watchdog
> timeout reset because the watchdog counter is running for more than
> max_heartbeat time.
>
> Using min_heartbeat instead of heartbeat does not guarantee that the
> watchdog won't trigger a reset, but at least it reduces the chances to be
> in such a case.
>
> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH 3/3] watchdog: at91sam9_wdt: increase security margin on watchdog counter reset
2013-11-03 17:52 ` Boris BREZILLON
@ 2013-11-03 17:52 ` Boris BREZILLON
-1 siblings, 0 replies; 14+ messages in thread
From: Boris BREZILLON @ 2013-11-03 17:52 UTC (permalink / raw)
To: Wim Van Sebroeck
Cc: Fabio Porcedda, Nicolas Ferre, Guenter Roeck, Yang Wenyou,
linux-kernel, linux-arm-kernel, linux-watchdog, Boris BREZILLON
Try to reset the watchdog counter 4 or 2 times more often than actually
requested, to avoid spurious watchdog reset.
If this is not possible because of the min_heartbeat value, reset it at
the min_heartbeat period.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
drivers/watchdog/at91sam9_wdt.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index ab0c4e0..489729b 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -158,6 +158,7 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
int err;
u32 mask = wdt->mr_mask;
unsigned long min_heartbeat = 1;
+ unsigned long max_heartbeat;
struct device *dev = &pdev->dev;
tmp = wdt_read(wdt, AT91_WDT_MR);
@@ -181,23 +182,29 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
if (delta < value)
min_heartbeat = ticks_to_hz_roundup(value - delta);
- wdt->heartbeat = ticks_to_hz_rounddown(value);
- if (!wdt->heartbeat) {
+ max_heartbeat = ticks_to_hz_rounddown(value);
+ if (!max_heartbeat) {
dev_err(dev,
"heartbeat is too small for the system to handle it correctly\n");
return -EINVAL;
}
- if (wdt->heartbeat < min_heartbeat + 4) {
+ /*
+ * Try to reset the watchdog counter 4 or 2 times more often than
+ * actually requested, to avoid spurious watchdog reset.
+ * If this is not possible because of the min_heartbeat value, reset
+ * it at the min_heartbeat period.
+ */
+ if ((max_heartbeat / 4) >= min_heartbeat)
+ wdt->heartbeat = max_heartbeat / 4;
+ else if ((max_heartbeat / 2) >= min_heartbeat)
+ wdt->heartbeat = max_heartbeat / 2;
+ else
wdt->heartbeat = min_heartbeat;
+
+ if (max_heartbeat < min_heartbeat + 4)
dev_warn(dev,
"min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");
- if (wdt->heartbeat < 4)
- dev_warn(dev,
- "heartbeat might be too small for the system to handle it correctly\n");
- } else {
- wdt->heartbeat -= 4;
- }
if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
err = request_irq(wdt->irq, wdt_interrupt,
--
1.7.9.5
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH 3/3] watchdog: at91sam9_wdt: increase security margin on watchdog counter reset
@ 2013-11-03 17:52 ` Boris BREZILLON
0 siblings, 0 replies; 14+ messages in thread
From: Boris BREZILLON @ 2013-11-03 17:52 UTC (permalink / raw)
To: linux-arm-kernel
Try to reset the watchdog counter 4 or 2 times more often than actually
requested, to avoid spurious watchdog reset.
If this is not possible because of the min_heartbeat value, reset it at
the min_heartbeat period.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
drivers/watchdog/at91sam9_wdt.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index ab0c4e0..489729b 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -158,6 +158,7 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
int err;
u32 mask = wdt->mr_mask;
unsigned long min_heartbeat = 1;
+ unsigned long max_heartbeat;
struct device *dev = &pdev->dev;
tmp = wdt_read(wdt, AT91_WDT_MR);
@@ -181,23 +182,29 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
if (delta < value)
min_heartbeat = ticks_to_hz_roundup(value - delta);
- wdt->heartbeat = ticks_to_hz_rounddown(value);
- if (!wdt->heartbeat) {
+ max_heartbeat = ticks_to_hz_rounddown(value);
+ if (!max_heartbeat) {
dev_err(dev,
"heartbeat is too small for the system to handle it correctly\n");
return -EINVAL;
}
- if (wdt->heartbeat < min_heartbeat + 4) {
+ /*
+ * Try to reset the watchdog counter 4 or 2 times more often than
+ * actually requested, to avoid spurious watchdog reset.
+ * If this is not possible because of the min_heartbeat value, reset
+ * it@the min_heartbeat period.
+ */
+ if ((max_heartbeat / 4) >= min_heartbeat)
+ wdt->heartbeat = max_heartbeat / 4;
+ else if ((max_heartbeat / 2) >= min_heartbeat)
+ wdt->heartbeat = max_heartbeat / 2;
+ else
wdt->heartbeat = min_heartbeat;
+
+ if (max_heartbeat < min_heartbeat + 4)
dev_warn(dev,
"min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");
- if (wdt->heartbeat < 4)
- dev_warn(dev,
- "heartbeat might be too small for the system to handle it correctly\n");
- } else {
- wdt->heartbeat -= 4;
- }
if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
err = request_irq(wdt->irq, wdt_interrupt,
--
1.7.9.5
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH 3/3] watchdog: at91sam9_wdt: increase security margin on watchdog counter reset
2013-11-03 17:52 ` Boris BREZILLON
@ 2013-11-03 18:32 ` Guenter Roeck
-1 siblings, 0 replies; 14+ messages in thread
From: Guenter Roeck @ 2013-11-03 18:32 UTC (permalink / raw)
To: Boris BREZILLON, Wim Van Sebroeck
Cc: Fabio Porcedda, Nicolas Ferre, Guenter Roeck, Yang Wenyou,
linux-kernel, linux-arm-kernel, linux-watchdog
On 11/03/2013 09:52 AM, Boris BREZILLON wrote:
> Try to reset the watchdog counter 4 or 2 times more often than actually
> requested, to avoid spurious watchdog reset.
> If this is not possible because of the min_heartbeat value, reset it at
> the min_heartbeat period.
>
> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH 3/3] watchdog: at91sam9_wdt: increase security margin on watchdog counter reset
@ 2013-11-03 18:32 ` Guenter Roeck
0 siblings, 0 replies; 14+ messages in thread
From: Guenter Roeck @ 2013-11-03 18:32 UTC (permalink / raw)
To: linux-arm-kernel
On 11/03/2013 09:52 AM, Boris BREZILLON wrote:
> Try to reset the watchdog counter 4 or 2 times more often than actually
> requested, to avoid spurious watchdog reset.
> If this is not possible because of the min_heartbeat value, reset it at
> the min_heartbeat period.
>
> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
^ permalink raw reply [flat|nested] 14+ messages in thread