The patch titled cpufreq: fix obvious condition statement error has been added to the -mm tree. Its filename is cpufreq-fix-obvious-condition-statement-error.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: cpufreq: fix obvious condition statement error From: Yi Yang <yi.y.yang@xxxxxxxxx> The function __cpufreq_set_policy in file drivers/cpufreq/cpufreq.c has a very obvious error: if (policy->min > data->min && policy->min > policy->max) { ret = -EINVAL; goto error_out; } This condtion statement is wrong because it returns -EINVAL only if policy->min is greater than policy->max (in this case, "policy->min > data->min" is true for ever.). In fact, it should return -EINVAL as well if policy->max is less than data->min. The correct condition should be: if (policy->min > data->max || policy->max < data->min) { The following test result testifies the above conclusion: Before applying this patch: [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies 2394000 1596000 [root@yangyi-dev /]# echo 1596000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq 1596000 [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq 1596000 [root@yangyi-dev /]# echo "2000000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq -bash: echo: write error: Invalid argument [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq 1596000 [root@yangyi-dev /]# echo "0" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq 1596000 [root@yangyi-dev /]# echo "1595000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq 1596000 [root@yangyi-dev /]# After applying this patch: [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies 2394000 1596000 [root@yangyi-dev /]# echo 1596000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq 1596000 [root@yangyi-dev /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq 1596000 [root@localhost /]# echo "2000000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq -bash: echo: write error: Invalid argument [root@localhost /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq 1596000 [root@localhost /]# echo "0" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq -bash: echo: write error: Invalid argument [root@localhost /]# echo "1595000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq -bash: echo: write error: Invalid argument [root@localhost /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq 1596000 [root@localhost /]# echo "1596000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq [root@localhost /]# echo "2394000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq [root@localhost /]# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq 2394000 [root@localhost /] Signed-off-by: Yi Yang <yi.y.yang@xxxxxxxxx> Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/cpufreq/cpufreq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN drivers/cpufreq/cpufreq.c~cpufreq-fix-obvious-condition-statement-error drivers/cpufreq/cpufreq.c --- a/drivers/cpufreq/cpufreq.c~cpufreq-fix-obvious-condition-statement-error +++ a/drivers/cpufreq/cpufreq.c @@ -1635,7 +1635,7 @@ static int __cpufreq_set_policy(struct c memcpy(&policy->cpuinfo, &data->cpuinfo, sizeof(struct cpufreq_cpuinfo)); - if (policy->min > data->min && policy->min > policy->max) { + if (policy->min > data->max || policy->max < data->min) { ret = -EINVAL; goto error_out; } _ Patches currently in -mm which might be from yi.y.yang@xxxxxxxxx are git-acpi.patch cpufreq-fix-obvious-condition-statement-error.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html