[PATCH] ACPI: fix processor throttling set error

From: Yi Yang
Date: Mon Jan 07 2008 - 02:45:58 EST

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Subject: ACPI: fix processor throttling set error
From: Yi Yang <yi.y.yang@xxxxxxxxx>

When echo some invalid values to /proc/acpi/processor/*/throttling,
there isn't any error info returned, on the contray, it sets
throttling value to some T* successfully, obviously, this is incorrect,
a correct way should be to let it fail and return error info.

This patch fixed the aforementioned issue, it also enables
/proc/acpi/processor/*/throttling to accept such values as 't0' and 'T0',
it also strictly limits /proc/acpi/processor/*/throttling only to accept
"*", "t*" and "T*", "*" is the throttling state value the processor can
support, current, it is 0 - 7.

Before applying this patch, the test result is below:

[root@localhost acpi]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T1
state available: T0 to T7
states:
T0: 100%
*T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost acpi]# echo "1xxxxxx" > /proc/acpi/processor/CPU0/throttling
[root@localhost acpi]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T1
state available: T0 to T7
states:
T0: 100%
*T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost acpi]# echo "0" > /proc/acpi/processor/CPU0/throttling
[root@localhost acpi]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost acpi]# cd /
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost /]# echo "T0" > /proc/acpi/processor/CPU0/throttling
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost /]# echo "T7" > /proc/acpi/processor/CPU0/throttling
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost /]# echo "T100" > /proc/acpi/processor/CPU0/throttling
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost /]# echo "xxx" > /proc/acpi/processor/CPU0/throttling
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost /]# echo "2xxxx" > /proc/acpi/processor/CPU0/throttling
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T2
state available: T0 to T7
states:
T0: 100%
T1: 87%
*T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost /]# echo "" > /proc/acpi/processor/CPU0/throttling
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost /]# echo "7777" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost /]# echo "7xxx" > /proc/acpi/processor/CPU0/throttling
[root@localhost /]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T7
state available: T0 to T7
states:
T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
*T7: 12%
[root@localhost /]#

After applying this patch, the test result is below:

[root@localhost linux-2.6.24-rc6]# echo > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo "" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo "0" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# echo "t0" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# echo "T0" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T0
state available: T0 to T7
states:
*T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
T7: 12%
[root@localhost linux-2.6.24-rc6]# echo "T7" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T7
state available: T0 to T7
states:
T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
*T7: 12%
[root@localhost linux-2.6.24-rc6]# echo "T8" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# vi drivers/acpi/processor_throttling.c
[root@localhost linux-2.6.24-rc6]# echo "T8" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo "t7" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# echo "t70" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo "70" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo "7000" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo "70" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo "xxx" > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo -n > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# echo -n "" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# echo $?
0
[root@localhost linux-2.6.24-rc6]# echo -n "" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T7
state available: T0 to T7
states:
T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
*T7: 12%
[root@localhost linux-2.6.24-rc6]# echo -n "" > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# cat /proc/acpi/processor/CPU0/throttling
state count: 8
active state: T7
state available: T0 to T7
states:
T0: 100%
T1: 87%
T2: 75%
T3: 62%
T4: 50%
T5: 37%
T6: 25%
*T7: 12%
[root@localhost linux-2.6.24-rc6]# echo t0 > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# echo T0 > /proc/acpi/processor/CPU0/throttling
[root@localhost linux-2.6.24-rc6]# echo Tt0 > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]# echo T > /proc/acpi/processor/CPU0/throttling
-bash: echo: write error: Invalid argument
[root@localhost linux-2.6.24-rc6]#

Signed-off-by: Yi Yang <yi.y.yang@xxxxxxxxx>
---
processor_throttling.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index 6742d7b..10035a6 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -898,7 +898,10 @@ static ssize_t acpi_processor_write_throttling(struct file *file,
int result = 0;
struct seq_file *m = file->private_data;
struct acpi_processor *pr = m->private;
- char state_string[12] = { '\0' };
+ char state_string[5] = "";
+ char *charp = NULL;
+ size_t state_val = 0;
+ char tmpbuf[5] = "";

if (!pr || (count > sizeof(state_string) - 1))
return -EINVAL;
@@ -907,10 +910,23 @@ static ssize_t acpi_processor_write_throttling(struct file *file,
return -EFAULT;

state_string[count] = '\0';
+ if ((count > 0) && (state_string[count-1] == '\n'))
+ state_string[count-1] = '\0';

- result = acpi_processor_set_throttling(pr,
- simple_strtoul(state_string,
- NULL, 0));
+ charp = state_string;
+ if ((state_string[0] == 't') || (state_string[0] == 'T'))
+ charp++;
+
+ state_val = simple_strtoul(charp, NULL, 0);
+ if (state_val >= pr->throttling.state_count)
+ return -EINVAL;
+
+ snprintf(tmpbuf, 5, "%d", state_val);
+
+ if (strcmp(tmpbuf, charp) != 0)
+ return -EINVAL;
+
+ result = acpi_processor_set_throttling(pr, state_val);
if (result)
return result;

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Next message: Tejun Heo: "Re: [Bluez-devel] Oops involving RFCOMM and sysfs"
Previous message: Paul Rolland: "Re: Module for simulating network default"
In reply to: Yi Yang: "[PATCH linux-acpi] fix acpi fan state set error"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]