[PATCH] Protect device shutdown from hot unplug events.
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From: Hugh Daschbach on 22 Mar 2010 13:40 While device_shutdown() walks through devices_kset to shutdown all devices, device unplug events may race to shutdown individual devices. Specifically, sd_shutdown(), on behalf of fc_starget_delete(), has been observed deleting devices during device_shutdown()'s list traversal. So we factor out list_for_each_entry_safe_reverse(...) in favor of while (!list_empty(...)). Signed-off-by: Hugh Daschbach <hdasch(a)broadcom.com> --- drivers/base/core.c | 25 ++++++++++++++++++++++--- 1 files changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index ef55df3..ac4c09a 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1729,10 +1729,25 @@ EXPORT_SYMBOL_GPL(device_move); */ void device_shutdown(void) { - struct device *dev, *devn; + struct device *dev; + + spin_lock(&devices_kset->list_lock); + /* + * Walk the devices list backward, shutting down each in turn. + * Beware that device unplug events may also start pulling + * devices offline, even as the system is shutting down. + */ + while (!list_empty(&devices_kset->list)) { + dev = list_entry(devices_kset->list.prev, struct device, + kobj.entry); + get_device(dev); + /* + * Make sure the device is off the kset list, in the + * event that dev->*->shutdown() doesn't remove it. + */ + list_del_init(&dev->kobj.entry); + spin_unlock(&devices_kset->list_lock); - list_for_each_entry_safe_reverse(dev, devn, &devices_kset->list, - kobj.entry) { if (dev->bus && dev->bus->shutdown) { dev_dbg(dev, "shutdown\n"); dev->bus->shutdown(dev); @@ -1740,6 +1755,10 @@ void device_shutdown(void) dev_dbg(dev, "shutdown\n"); dev->driver->shutdown(dev); } + put_device(dev); + + spin_lock(&devices_kset->list_lock); } + spin_unlock(&devices_kset->list_lock); async_synchronize_full(); } -- 1.7.0.rc0.48.gdace5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |