On Fri, 22 Jan 2021 17:23:36 +0100 "Rafael J. Wysocki" <rafael@xxxxxxxxxx> wrote: > On Thu, Jan 14, 2021 at 7:35 PM Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: >> >> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> >> >> Calling acpi_thermal_check() from acpi_thermal_notify() directly >> is problematic if _TMP triggers Notify () on the thermal zone for >> which it has been evaluated (which happens on some systems), because >> it causes a new acpi_thermal_notify() invocation to be queued up >> every time and if that takes place too often, an indefinite number of >> pending work items may accumulate in kacpi_notify_wq over time. >> >> Besides, it is not really useful to queue up a new invocation of >> acpi_thermal_check() if one of them is pending already. >> >> For these reasons, rework acpi_thermal_notify() to queue up a thermal >> check instead of calling acpi_thermal_check() directly and only allow >> one thermal check to be pending at a time. Moreover, only allow one >> acpi_thermal_check_fn() instance at a time to run >> thermal_zone_device_update() for one thermal zone and make it return >> early if it sees other instances running for the same thermal zone. >> >> While at it, fold acpi_thermal_check() into acpi_thermal_check_fn(), >> as it is only called from there after the other changes made here. >> >> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=208877 >> Reported-by: Stephen Berman <stephen.berman@xxxxxxx> >> Diagnosed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> >> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Well, it's been over a week since this was posted. > > Does anyone have any comments? Sorry, I haven't been able to make time to test the patch yet, but I'll try to do so this weekend. Is it just the patch below that I should apply, ignoring the previous patches you sent? And can I apply it to the current mainline kernel? Thanks, Steve Berman >> --- >> drivers/acpi/thermal.c | 46 +++++++++++++++++++++++++++++++++------------- >> 1 file changed, 33 insertions(+), 13 deletions(-) >> >> Index: linux-pm/drivers/acpi/thermal.c >> =================================================================== >> --- linux-pm.orig/drivers/acpi/thermal.c >> +++ linux-pm/drivers/acpi/thermal.c >> @@ -174,6 +174,8 @@ struct acpi_thermal { >> struct thermal_zone_device *thermal_zone; >> int kelvin_offset; /* in millidegrees */ >> struct work_struct thermal_check_work; >> + struct mutex thermal_check_lock; >> + refcount_t thermal_check_count; >> }; >> >> /* -------------------------------------------------------------------------- >> @@ -495,14 +497,6 @@ static int acpi_thermal_get_trip_points( >> return 0; >> } >> >> -static void acpi_thermal_check(void *data) >> -{ >> - struct acpi_thermal *tz = data; >> - >> - thermal_zone_device_update(tz->thermal_zone, >> - THERMAL_EVENT_UNSPECIFIED); >> -} >> - >> /* sys I/F for generic thermal sysfs support */ >> >> static int thermal_get_temp(struct thermal_zone_device *thermal, int *temp) >> @@ -900,6 +894,12 @@ static void acpi_thermal_unregister_ther >> Driver Interface >> -------------------------------------------------------------------------- */ >> >> +static void acpi_queue_thermal_check(struct acpi_thermal *tz) >> +{ >> + if (!work_pending(&tz->thermal_check_work)) >> + queue_work(acpi_thermal_pm_queue, &tz->thermal_check_work); >> +} >> + >> static void acpi_thermal_notify(struct acpi_device *device, u32 event) >> { >> struct acpi_thermal *tz = acpi_driver_data(device); >> @@ -910,17 +910,17 @@ static void acpi_thermal_notify(struct a >> >> switch (event) { >> case ACPI_THERMAL_NOTIFY_TEMPERATURE: >> - acpi_thermal_check(tz); >> + acpi_queue_thermal_check(tz); >> break; >> case ACPI_THERMAL_NOTIFY_THRESHOLDS: >> acpi_thermal_trips_update(tz, ACPI_TRIPS_REFRESH_THRESHOLDS); >> - acpi_thermal_check(tz); >> + acpi_queue_thermal_check(tz); >> acpi_bus_generate_netlink_event(device->pnp.device_class, >> dev_name(&device->dev), event, 0); >> break; >> case ACPI_THERMAL_NOTIFY_DEVICES: >> acpi_thermal_trips_update(tz, ACPI_TRIPS_REFRESH_DEVICES); >> - acpi_thermal_check(tz); >> + acpi_queue_thermal_check(tz); >> acpi_bus_generate_netlink_event(device->pnp.device_class, >> dev_name(&device->dev), event, 0); >> break; >> @@ -1020,7 +1020,25 @@ static void acpi_thermal_check_fn(struct >> { >> struct acpi_thermal *tz = container_of(work, struct acpi_thermal, >> thermal_check_work); >> - acpi_thermal_check(tz); >> + >> + /* >> + * In general, it is not sufficient to check the pending bit, because >> + * subsequent instances of this function may be queued after one of them >> + * has started running (e.g. if _TMP sleeps). Avoid bailing out if just >> + * one of them is running, though, because it may have done the actual >> + * check some time ago, so allow at least one of them to block on the >> + * mutex while another one is running the update. >> + */ >> + if (!refcount_dec_not_one(&tz->thermal_check_count)) >> + return; >> + >> + mutex_lock(&tz->thermal_check_lock); >> + >> + thermal_zone_device_update(tz->thermal_zone, THERMAL_EVENT_UNSPECIFIED); >> + >> + refcount_inc(&tz->thermal_check_count); >> + >> + mutex_unlock(&tz->thermal_check_lock); >> } >> >> static int acpi_thermal_add(struct acpi_device *device) >> @@ -1052,6 +1070,8 @@ static int acpi_thermal_add(struct acpi_ >> if (result) >> goto free_memory; >> >> + refcount_set(&tz->thermal_check_count, 3); >> + mutex_init(&tz->thermal_check_lock); >> INIT_WORK(&tz->thermal_check_work, acpi_thermal_check_fn); >> >> pr_info(PREFIX "%s [%s] (%ld C)\n", acpi_device_name(device), >> @@ -1117,7 +1137,7 @@ static int acpi_thermal_resume(struct de >> tz->state.active |= tz->trips.active[i].flags.enabled; >> } >> >> - queue_work(acpi_thermal_pm_queue, &tz->thermal_check_work); >> + acpi_queue_thermal_check(tz); >> >> return AE_OK; >> } >> >> >>
