Hi, > From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx] > Sent: Tuesday, December 02, 2014 6:33 AM > > 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. OK. I'll post it to this thread. Thanks and best regards -Lv ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
