On 18 August 2026 23:52:21 BST, Masami Hiramatsu <[email protected]>
wrote:
>On Tue, 18 Aug 2026 01:49:20 +0000
>Bradley Morgan <[email protected]> wrote:
>
>> This enabled knob is a disgusting terrible hack. It has rolled its
>> own read/write pair since 2007, writing '1' or '0' into a three byte
>> buffer by hand just to print a single character, with an XXX comment
>> begging debugfs for write callbacks on bool files.
>> DEFINE_DEBUGFS_ATTRIBUTE showed up in 2016 and does exactly that, so
>> the disgusting terrible hack has outlived its excuse for nine years.
>> Kill it, and the stale comment with it.
>
>Hm, OK, but please calm down. Just describe the technical reason here.
>
>>
>> The behavior does not change, except the write only accepts 0/1 now
>> instead of y/n/on/off, and nothing uses anything else.
>
>I think this comment is needed.
>
What do you suggest?
I'm saying
/* Let's kill this hack */
(I love using the word hack!)
>Please add Signed-off-by.
>
V2 acks it
>The code looks good to me.
>
>Thanks,
>
>> ---
>> kernel/kprobes.c | 43 +++++++++----------------------------------
>> 1 file changed, 9 insertions(+), 34 deletions(-)
>>
>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>> index bfc89083daa9..044c6b5fd2aa 100644
>> --- a/kernel/kprobes.c
>> +++ b/kernel/kprobes.c
>> @@ -3013,47 +3013,22 @@ static int disarm_all_kprobes(void)
>> return ret;
>> }
>>
>> -/*
>> - * XXX: The debugfs bool file interface doesn't allow for callbacks
>> - * when the bool state is switched. We can reuse that facility when
>> - * available
>> - */
>> -static ssize_t read_enabled_file_bool(struct file *file,
>> - char __user *user_buf, size_t count, loff_t *ppos)
>> +static int kprobes_enabled_set(void *data, u64 val)
>> {
>> - char buf[3];
>> + if (val)
>> + return arm_all_kprobes();
>>
>> - if (!kprobes_all_disarmed)
>> - buf[0] = '1';
>> - else
>> - buf[0] = '0';
>> - buf[1] = '\n';
>> - buf[2] = 0x00;
>> - return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
>> + return disarm_all_kprobes();
>> }
>>
>> -static ssize_t write_enabled_file_bool(struct file *file,
>> - const char __user *user_buf, size_t count, loff_t *ppos)
>> +static int kprobes_enabled_get(void *data, u64 *val)
>> {
>> - bool enable;
>> - int ret;
>> -
>> - ret = kstrtobool_from_user(user_buf, count, &enable);
>> - if (ret)
>> - return ret;
>> -
>> - ret = enable ? arm_all_kprobes() : disarm_all_kprobes();
>> - if (ret)
>> - return ret;
>> -
>> - return count;
>> + *val = !kprobes_all_disarmed;
>> + return 0;
>> }
>>
>> -static const struct file_operations fops_kp = {
>> - .read = read_enabled_file_bool,
>> - .write = write_enabled_file_bool,
>> - .llseek = default_llseek,
>> -};
>> +DEFINE_DEBUGFS_ATTRIBUTE(fops_kp, kprobes_enabled_get,
>> + kprobes_enabled_set, "%llu\n");
>>
>> static int __init debugfs_kprobe_init(void)
>> {
>> --
>> 2.47.3
>>
>
>
>
Thanks!
