[PATCH] ACPI: fix processor limit set error

[Yi Yang <yi.y.yang@intel.com>]

Subject: ACPI: fix processor limit set error
From: Yi Yang <yi.y.yang@intel.com>

when echo some invalid values to /proc/acpi/processor/CPU*/limit,
it doesn't return any error info, on the contrary, it successes
and sets some other values, for example:

[root@localhost /]# echo "0:0A" >/proc/acpi/processor/CPU0/limit
[root@localhost /]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T0
user limit:              P0:T0
thermal limit:           P0:T0
[root@localhost /]# echo "0:0F" >/proc/acpi/processor/CPU0/limit
[root@localhost /]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T0
user limit:              P0:T0
thermal limit:           P0:T0
[root@localhost /]# echo "0:0 0:1 0:2" >/proc/acpi/processor/CPU0/limit
[root@localhost /]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T0
user limit:              P0:T0
thermal limit:           P0:T0
[root@localhost /]#

A correct way is that it should fail and return error info.

This patch fixed this issue, it accepts not only such inputs as "*:*",
but also accepts such inputs as "p*:t*" or "P*:T*" or "p*:*" or "*:t*",
the former "*" in inputs means the allowed processor performance state,
currently it is only a stub and not set to the processor limit data
structure, the latter "*" means the allowed processor throttling state
which rages from 0 to 7 generally. This patch strictly limits inputs to
meet the above conditions, any input which can't meet the above conditions
is considered as invalid input.

Before applying this patch, the test result is below:

[root@localhost /]# echo "0:0A" >/proc/acpi/processor/CPU0/limit
[root@localhost /]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T0
user limit:              P0:T0
thermal limit:           P0:T0
[root@localhost /]# echo "0:0F" >/proc/acpi/processor/CPU0/limit
[root@localhost /]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T0
user limit:              P0:T0
thermal limit:           P0:T0
[root@localhost /]# echo "10:2F" >/proc/acpi/processor/CPU0/limit
[root@localhost /]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T2
user limit:              P0:T2
thermal limit:           P0:T0
[root@localhost /]# echo "0:0 0:1 0:2" >/proc/acpi/processor/CPU0/limit
[root@localhost /]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T0
user limit:              P0:T0
thermal limit:           P0:T0
[root@localhost /]#

After applying this patch, the test result is below:

[root@localhost ~]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T0
user limit:              P0:T0
thermal limit:           P0:T0
[root@localhost ~]# echo "0:0A" > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# echo "0:0F" > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# echo "P0:T1" > /proc/acpi/processor/CPU0/limit
[root@localhost ~]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T1
user limit:              P0:T1
thermal limit:           P0:T0
[root@localhost ~]# echo "p0:t1" > /proc/acpi/processor/CPU0/limit
[root@localhost ~]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T1
user limit:              P0:T1
thermal limit:           P0:T0
[root@localhost ~]# echo "p0:x1" > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# echo "q0:x1" > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# echo "p0:1" > /proc/acpi/processor/CPU0/limit
[root@localhost ~]# echo "q0:x1" > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T1
user limit:              P0:T1
thermal limit:           P0:T0
[root@localhost ~]# echo "0:t1" > /proc/acpi/processor/CPU0/limit
[root@localhost ~]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T1
user limit:              P0:T1
thermal limit:           P0:T0
[root@localhost ~]# echo "0:t1F" > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# echo "" > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# echo "0:0 0:0 0:2 " > /proc/acpi/processor/CPU0/limit
-bash: echo: write error: Invalid argument
[root@localhost ~]# echo "P0:T1" > /proc/acpi/processor/CPU0/limit
[root@localhost ~]# cat /proc/acpi/processor/CPU0/limit
active limit:            P0:T1
user limit:              P0:T1
thermal limit:           P0:T0
[root@localhost ~]#


Signed-off-by: Yi Yang <yi.y.yang@intel.com>
---
 processor_thermal.c |   42 +++++++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/drivers/acpi/processor_thermal.c b/drivers/acpi/processor_thermal.c
index 06e6f3f..262d56e 100644
--- a/drivers/acpi/processor_thermal.c
+++ b/drivers/acpi/processor_thermal.c
@@ -349,9 +349,11 @@ static ssize_t acpi_processor_write_limit(struct file * file,
 	int result = 0;
 	struct seq_file *m = file->private_data;
 	struct acpi_processor *pr = m->private;
-	char limit_string[25] = { '\0' };
+	char limit_string[10] = "";
 	int px = 0;
 	int tx = 0;
+	char *tmpp = NULL;
+	char tmpstring[10] = "";
 
 
 	if (!pr || (count > sizeof(limit_string) - 1)) {
@@ -363,21 +365,39 @@ static ssize_t acpi_processor_write_limit(struct file * file,
 	}
 
 	limit_string[count] = '\0';
+	if ((count > 0) && (limit_string[count-1] == '\n'))
+		limit_string[count-1] = '\0';
 
-	if (sscanf(limit_string, "%d:%d", &px, &tx) != 2) {
-		printk(KERN_ERR PREFIX "Invalid data format\n");
+	tmpp = memchr(limit_string, ':', count);
+	if (tmpp == NULL)
+		return -EINVAL;
+
+	*tmpp = '\0';
+	tmpp = limit_string;
+	if ((limit_string[0] == 'p') || (limit_string[0] == 'P'))
+		tmpp++;
+	px = simple_strtoul(tmpp, NULL, 0);
+	snprintf(tmpstring, 10, "%d", px);
+	if (strcmp(tmpp, tmpstring) != 0)
+		return -EINVAL;
+
+	tmpp += strlen(tmpp) + 1;
+	if ((tmpp[0] == 't') || (tmpp[0] == 'T'))
+		tmpp++;
+	tx = simple_strtoul(tmpp, NULL, 0);
+	if (tx > (pr->throttling.state_count - 1))
+		return -EINVAL;
+	snprintf(tmpstring, 10, "%d", tx);
+	if (strcmp(tmpp, tmpstring) != 0)
 		return -EINVAL;
-	}
 
 	if (pr->flags.throttling) {
-		if ((tx < 0) || (tx > (pr->throttling.state_count - 1))) {
-			printk(KERN_ERR PREFIX "Invalid tx\n");
-			return -EINVAL;
-		}
 		pr->limit.user.tx = tx;
-	}
-
-	result = acpi_processor_apply_limit(pr);
+		result = acpi_processor_apply_limit(pr);
+		if (result != 0)
+			return result;
+	} else
+		return -ENODEV;
 
 	return count;
 }