Shaohua Li wrote: > On Thu, 2007-09-27 at 11:30 +0800, Zhang Rui wrote: >> Hi, all, >> >> I found a bug that linux/acpi may execute notify handler that >> has been removed. >> >> When a system notify(0~0x7f) is received, linux/acpi will >> first invoke the generic system notify handler (acpi_bus_notify) >> and then invoke the per-device notify handler if present. >> >> In my case, I add some code in acpi_bus_notify for battery >> hotplug support, so that the generic system notify handler will >> remove the battery device, including the per-device notify handler >> acpi_battery_notify() when receiving notification >> ACPI_NOTIFY_EJECT_REQUEST. >> But linux/acpi invokes the per-device notify handler soon and >> this breaks the system. >> >> Further more, device hot-removal is not the only case to encounter >> this bug. For example, linux/acpi receives a notification and adds it >> in the workqueue, and then the driver(notify handler) is removed >> before kacpid_notify invoke it... > For the non-hotplug case, adding a flush work queue just after notify > handler is removed should be ok. I think, the real problem with ACPI hotplug is that we know which devices might appear -- they are all enumerated in DSDT, but we don't add them until they appear. If we do .add for all devices in DSDT, and then just .start/.stop them as they appear/disappear, we will have to do much less work, and avoid a problem described above... Regards, Alex. - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
