Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH V2 1/1] thermal/sysfs: Clear cooling_device_stats_attr_group before initialized | Date | Fri, 22 Jul 2022 20:42:17 +0200 |
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On Friday, July 22, 2022 7:18:42 PM CEST Rafael J. Wysocki wrote: > On Fri, Jul 22, 2022 at 10:44 AM Di Shen <di.shen@unisoc.com> wrote: > > > > There's a space allocated for cooling_device_stats_attr_group > > within cooling_device_attr_groups. This space is shared by all > > cooling devices. > > That's correct. > > > If the stats structure of one cooling device successfully > > creates stats sysfs. After that, another cooling device fails > > to get max_states in cooling_device_stats_setup(). It can > > return directly without initializing the stats structure, but > > the cooling_device_stats_attr_group is still the attribute > > group of the last cooling device. > > I cannot parse the above, sorry. > > For example, how can a "stats structure of one cooling device" create > anything? As a data structure, it is a passive entity, so it doesn't > carry out any actions. > > I think (but I am not sure) that you are referring to the error code > path in which the ->get_max_state() callback fails for a cooling > device after cooling_device_stats_setup() has completed successfully > for another one. > > > At this time, read or write stats sysfs nodes can cause kernel > > crash. Like the following, kernel crashed when > > 'cat time_in_state_ms'. > > > > [<5baac8d4>] panic+0x1b4/0x3c8 > > [<9d287b0f>] arm_notify_die+0x0/0x78 > > [<094fc22c>] __do_kernel_fault+0x94/0xa4 > > [<3b4b69a4>] do_page_fault+0xd4/0x364 > > [<23793e7a>] do_translation_fault+0x38/0xc0 > > [<6e5cc52a>] do_DataAbort+0x4c/0xd0 > > [<a28c16b8>] __dabt_svc+0x5c/0xa0 > > [<747516ae>] _raw_spin_lock+0x20/0x60 > > [<9a9e4cd4>] time_in_state_ms_show+0x28/0x148 > > [<cb78325e>] dev_attr_show+0x38/0x64 > > [<aea3e364>] sysfs_kf_seq_show+0x8c/0xf0 > > [<c0a843ab>] seq_read+0x244/0x620 > > [<b316b374>] vfs_read+0xd8/0x218 > > [<3aebf5fa>] sys_read+0x80/0xe4 > > [<7cf100f5>] ret_fast_syscall+0x0/0x28 > > [<08cbe22f>] 0xbe8c1198 > > > > stats sysfs: > > phone:/sys/class/thermal/cooling_device2/stats # ls > > reset time_in_state_ms total_trans trans_table > > > > The same as cat total_trans, trans_table, and echo reset.
So does the (untested) patch below work too?
--- drivers/thermal/thermal_sysfs.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
Index: linux-pm/drivers/thermal/thermal_sysfs.c =================================================================== --- linux-pm.orig/drivers/thermal/thermal_sysfs.c +++ linux-pm/drivers/thermal/thermal_sysfs.c @@ -813,12 +813,13 @@ static const struct attribute_group cool static void cooling_device_stats_setup(struct thermal_cooling_device *cdev) { + const struct attribute_group *stats_attr_group = NULL; struct cooling_dev_stats *stats; unsigned long states; int var; if (cdev->ops->get_max_state(cdev, &states)) - return; + goto out; states++; /* Total number of states is highest state + 1 */ @@ -828,7 +829,7 @@ static void cooling_device_stats_setup(s stats = kzalloc(var, GFP_KERNEL); if (!stats) - return; + goto out; stats->time_in_state = (ktime_t *)(stats + 1); stats->trans_table = (unsigned int *)(stats->time_in_state + states); @@ -838,9 +839,12 @@ static void cooling_device_stats_setup(s spin_lock_init(&stats->lock); + stats_attr_group = &cooling_device_stats_attr_group; + +out: /* Fill the empty slot left in cooling_device_attr_groups */ var = ARRAY_SIZE(cooling_device_attr_groups) - 2; - cooling_device_attr_groups[var] = &cooling_device_stats_attr_group; + cooling_device_attr_groups[var] = stats_attr_group; } static void cooling_device_stats_destroy(struct thermal_cooling_device *cdev)
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