On Monday, December 01, 2014 05:03:04 AM Zheng, Lv wrote: > Hi, Rafael > > > From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx] > > Sent: Monday, December 01, 2014 9:53 AM > > > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > There is a race condition between acpi_hw_disable_all_gpes() or > > acpi_enable_all_wakeup_gpes() and acpi_ev_asynch_enable_gpe() such > > that if the latter wins the race, it may mistakenly enable a GPE > > disabled by the former. This may lead to premature system wakeups > > during system suspend and potentially to more serious consequences. > > > > The source of the problem is how acpi_hw_low_set_gpe() works when > > passed ACPI_GPE_CONDITIONAL_ENABLE as the second argument. In that > > case, the GPE will be enabled if the corresponding bit is set in the > > enable_for_run mask of the GPE enable register containing that bit. > > However, acpi_hw_disable_all_gpes() and acpi_enable_all_wakeup_gpes() > > don't modify the enable_for_run masks of GPE registers when writing > > to them. In consequence, if acpi_ev_asynch_enable_gpe(), which > > eventually calls acpi_hw_low_set_gpe() with the second argument > > equal to ACPI_GPE_CONDITIONAL_ENABLE, is executed in parallel with > > one of these functions, it may reverse changes made by them. > > > > To fix the problem, introduce a new enable_mask field in struct > > acpi_gpe_register_info in which to store the current mask of > > enabled GPEs and modify acpi_hw_low_set_gpe() to take this > > mask into account instead of enable_for_run when its second > > argument is equal to ACPI_GPE_CONDITIONAL_ENABLE. Also modify > > the low-level routines called by acpi_hw_disable_all_gpes(), > > acpi_enable_all_wakeup_gpes() and acpi_enable_all_runtime_gpes() > > to update the enable_mask masks of GPE registers after all > > (successful) writes to those registers. > > Both the solution and the patch looks OK. > You'll still need the following fix to ensure the atomicity of acpi_ev_asynch_enable_gpe(): > https://bugzilla.kernel.org/attachment.cgi?id=157391 > > Acked-by: Lv Zheng <lv.zheng@xxxxxxxxx> Thanks! Can you please submit the patch from https://bugzilla.kernel.org/attachment.cgi?id=157391 to linux-acpi officially? I'd like it to be included into 3.19 as a fix. Rafael -- 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
