weird cooling_device/cur_state sysfs behaviour
From: Willy Wolff
Date: Fri Mar 20 2020 - 11:11:00 EST
Hi all,
Hope you're doing well with the situation.
I fill that my board get a cold too...
When I write to a sysfs node, I have a weird behaviour about the function that is called behind.
This bug appears on an arm32 odroid-xu3, and only after v5.4, v5.3.18 behave correctly.
Here my modification to see what's going on:
diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index aa99edb4dff7..a437ae3f4b9f 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -706,11 +706,22 @@ cur_state_store(struct device *dev, struct device_attribute *attr,
unsigned long state;
int result;
- if (sscanf(buf, "%ld\n", &state) != 1)
+ dump_stack();
+
+ printk(KERN_INFO "%s:%d:%s buf = \"%s\", count = %zu\n",
+ __FILE__, __LINE__, __func__, buf, count);
+
+ if (sscanf(buf, "%ld\n", &state) != 1) {
+ printk(KERN_INFO "%s:%d:%s\n",
+ __FILE__, __LINE__, __func__);
return -EINVAL;
+ }
- if ((long)state < 0)
+ if ((long)state < 0) {
+ printk(KERN_INFO "%s:%d:%s\n",
+ __FILE__, __LINE__, __func__);
return -EINVAL;
+ }
mutex_lock(&cdev->lock);
@@ -719,9 +730,14 @@ cur_state_store(struct device *dev, struct device_attribute *attr,
thermal_cooling_device_stats_update(cdev, state);
mutex_unlock(&cdev->lock);
+
+ printk(KERN_INFO "%s:%d:%s result = %d, count = %zu\n",
+ __FILE__, __LINE__, __func__, result, count);
+
return result ? result : count;
}
+
static struct device_attribute
dev_attr_cdev_type = __ATTR(type, 0444, cdev_type_show, NULL);
static DEVICE_ATTR_RO(max_state);
And here the prob:
Thursday 2019-02-14 10:26:46 root@odroid-xu3-0 ~
$ echo 11 > /sys/devices/virtual/thermal/cooling_device1/cur_state
[ 908.109955] CPU: 5 PID: 500 Comm: bash Not tainted 5.4.0-dirty #6
[ 908.114910] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 908.121014] [<c0112f08>] (unwind_backtrace) from [<c010df38>] (show_stack+0x10/0x14)
[ 908.128796] [<c010df38>] (show_stack) from [<c0ae89cc>] (dump_stack+0xa4/0xd0)
[ 908.135962] [<c0ae89cc>] (dump_stack) from [<c0759e0c>] (cur_state_store+0x2c/0x14c)
[ 908.143686] [<c0759e0c>] (cur_state_store) from [<c033b360>] (kernfs_fop_write+0x100/0x1e0)
[ 908.152035] [<c033b360>] (kernfs_fop_write) from [<c02a93f4>] (__vfs_write+0x2c/0x1c0)
[ 908.159908] [<c02a93f4>] (__vfs_write) from [<c02ac25c>] (vfs_write+0xa4/0x188)
[ 908.167163] [<c02ac25c>] (vfs_write) from [<c02ac4b0>] (ksys_write+0x58/0xd0)
[ 908.174242] [<c02ac4b0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28)
[ 908.181874] Exception stack(0xeb915fa8 to 0xeb915ff0)
[ 908.186800] 5fa0: 00000074 0050ba08 00000001 0050ba08 00000003 00000000
[ 908.195083] 5fc0: 00000074 0050ba08 b6eb3db0 00000004 00000003 00000003 00000000 00000000
[ 908.203218] 5fe0: 00000004 bef3c830 b6e4b5b3 b6dd4746
[ 908.210744] drivers/thermal/thermal_sysfs.c:712:cur_state_store buf = "11
[ 908.210744] ", count = 3
[ 908.221520] drivers/thermal/thermal_sysfs.c:735:cur_state_store result = 1, count = 3
[ 908.228681] CPU: 5 PID: 500 Comm: bash Not tainted 5.4.0-dirty #6
[ 908.234268] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 908.240372] [<c0112f08>] (unwind_backtrace) from [<c010df38>] (show_stack+0x10/0x14)
[ 908.248159] [<c010df38>] (show_stack) from [<c0ae89cc>] (dump_stack+0xa4/0xd0)
[ 908.255325] [<c0ae89cc>] (dump_stack) from [<c0759e0c>] (cur_state_store+0x2c/0x14c)
[ 908.263048] [<c0759e0c>] (cur_state_store) from [<c033b360>] (kernfs_fop_write+0x100/0x1e0)
[ 908.271398] [<c033b360>] (kernfs_fop_write) from [<c02a93f4>] (__vfs_write+0x2c/0x1c0)
[ 908.279271] [<c02a93f4>] (__vfs_write) from [<c02ac25c>] (vfs_write+0xa4/0x188)
[ 908.286527] [<c02ac25c>] (vfs_write) from [<c02ac4b0>] (ksys_write+0x58/0xd0)
[ 908.293608] [<c02ac4b0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28)
[ 908.301241] Exception stack(0xeb915fa8 to 0xeb915ff0)
[ 908.306168] 5fa0: 00000074 0050ba09 00000001 0050ba09 00000002 00000000
[ 908.314448] 5fc0: 00000074 0050ba09 b6eb3db0 00000004 00000003 00000003 00000000 00000000
[ 908.322581] 5fe0: 00000004 bef3c830 b6e4b5b3 b6dd4746
[ 908.328660] drivers/thermal/thermal_sysfs.c:712:cur_state_store buf = "1
[ 908.328660] ", count = 2
[ 908.338432] drivers/thermal/thermal_sysfs.c:735:cur_state_store result = 1, count = 2
[ 908.345695] CPU: 5 PID: 500 Comm: bash Not tainted 5.4.0-dirty #6
[ 908.351172] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 908.357276] [<c0112f08>] (unwind_backtrace) from [<c010df38>] (show_stack+0x10/0x14)
[ 908.365062] [<c010df38>] (show_stack) from [<c0ae89cc>] (dump_stack+0xa4/0xd0)
[ 908.372227] [<c0ae89cc>] (dump_stack) from [<c0759e0c>] (cur_state_store+0x2c/0x14c)
[ 908.379951] [<c0759e0c>] (cur_state_store) from [<c033b360>] (kernfs_fop_write+0x100/0x1e0)
[ 908.388302] [<c033b360>] (kernfs_fop_write) from [<c02a93f4>] (__vfs_write+0x2c/0x1c0)
[ 908.396176] [<c02a93f4>] (__vfs_write) from [<c02ac25c>] (vfs_write+0xa4/0x188)
[ 908.403433] [<c02ac25c>] (vfs_write) from [<c02ac4b0>] (ksys_write+0x58/0xd0)
[ 908.410511] [<c02ac4b0>] (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28)
[ 908.418145] Exception stack(0xeb915fa8 to 0xeb915ff0)
[ 908.423068] 5fa0: 00000074 0050ba0a 00000001 0050ba0a 00000001 00000000
[ 908.431352] 5fc0: 00000074 0050ba0a b6eb3db0 00000004 00000003 00000003 00000000 00000000
[ 908.439487] 5fe0: 00000004 bef3c830 b6e4b5b3 b6dd4746
[ 908.445365] drivers/thermal/thermal_sysfs.c:712:cur_state_store buf = "
[ 908.445365] ", count = 1
[ 908.454762] drivers/thermal/thermal_sysfs.c:716:cur_state_store
-bash: echo: write error: Invalid argument
As you can see, the function is recalled with one character less, until the "buffer is empty".
I don't understand why. Can anybody help me for this thing?
Many thanks in advance.
Best Regards,
Willy