If somebody removes that driver, it will unregister the platform device
which will set watchdog_dev.c:wdd to NULL, which will cause a kernel panic
the next time the watchdog daemon accesses /dev/watchdog. You can easily
reproduce the panic by doing just that.
Therefore we shouldn't be allowed to remove lpc_sch while the watchdog
is in use, so this patch keeps it pinned.
Signed-off-by: Chris Wilson <chris+github@xxxxxxxxx>
---
drivers/watchdog/ie6xx_wdt.c | 23 ++++++++++++++++++++++-
1 files changed, 22 insertions(+), 1 deletions(-)
diff --git a/drivers/watchdog/ie6xx_wdt.c b/drivers/watchdog/ie6xx_wdt.c
index 6b7b520..6d95120 100644
--- a/drivers/watchdog/ie6xx_wdt.c
+++ b/drivers/watchdog/ie6xx_wdt.c
@@ -83,6 +83,7 @@ MODULE_PARM_DESC(resetmode,
static struct {
unsigned short sch_wdtba;
struct spinlock unlock_sequence;
+ struct platform_device *pdev;
#ifdef CONFIG_DEBUG_FS
struct dentry *debugfs;
#endif
@@ -147,6 +148,15 @@ static int ie6xx_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
static int ie6xx_wdt_start(struct watchdog_device *wdd)
{
+ /* watchdog_dev.c has pinned this module, but nobody pinned lpc_sch.
+ If it's unloaded while the device is open, the device will be
+ unregistered, watchdog_dev will set its wdd to NULL and the next file
+ operation will panic. So we'd better pin lpc_sch, or more accurately,
+ whoever created the parent (pci_device) of the platform_device that
+ we're using, because it wasn't us! */
+ if (!try_module_get(ie6xx_wdt_data.pdev->dev.parent->driver->owner))
+ return -ESHUTDOWN; // driver is unloading
+
ie6xx_wdt_set_timeout(wdd, wdd->timeout);
/* Enable the watchdog timer */
@@ -167,6 +177,8 @@ static int ie6xx_wdt_stop(struct watchdog_device *wdd)
outb(0, ie6xx_wdt_data.sch_wdtba + WDTLR);
spin_unlock(&ie6xx_wdt_data.unlock_sequence);
+ module_put(ie6xx_wdt_data.pdev->dev.parent->driver->owner);
+
return 0;
}
@@ -277,8 +289,15 @@ static int __devinit ie6xx_wdt_probe(struct platform_device *pdev)
outb(WDT_TIMEOUT, ie6xx_wdt_data.sch_wdtba + RR1);
}
+ // Need to remember our platform_device so we can pin its owner
+ // while the watchdog is open.
+ ie6xx_wdt_data.pdev = pdev;
+ dev_info(&pdev->dev, "pdev owner: %s\n", pdev->dev.driver->owner->name);
+
ie6xx_wdt_dev.timeout = timeout;
- watchdog_set_nowayout(&ie6xx_wdt_dev, nowayout);
+ // watchdog_set_nowayout(&ie6xx_wdt_dev, nowayout);
+ if (nowayout)
+ set_bit(WDOG_NO_WAY_OUT, &ie6xx_wdt_dev.status);
spin_lock_init(&ie6xx_wdt_data.unlock_sequence);
@@ -304,6 +323,7 @@ misc_register_error:
ie6xx_wdt_debugfs_exit();
release_region(res->start, resource_size(res));
ie6xx_wdt_data.sch_wdtba = 0;
+ ie6xx_wdt_data.pdev = NULL;
return ret;
}
@@ -317,6 +337,7 @@ static int __devexit ie6xx_wdt_remove(struct platform_device *pdev)
ie6xx_wdt_debugfs_exit();
release_region(res->start, resource_size(res));
ie6xx_wdt_data.sch_wdtba = 0;
+ ie6xx_wdt_data.pdev = NULL;
return 0;
}
--
1.7.5.4
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