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SubjectRe: [PATCH] tty: only print sysrq help for handlers that are enabled
On 12/24/2013 12:04 AM, shawn@churchofgit.com wrote:
>> On Tue, Dec 03, 2013 at 07:55:25AM -0800, Shawn Landden wrote:
>>> Also print out a notice when sysrq is in selective mode.
>>>
>>> Signed-off-by: Shawn Landden <shawn@churchofgit.com>
>>> ---
>>> drivers/tty/sysrq.c | 7 ++++++-
>>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
>>> index ce396ec..4eee0e4 100644
>>> --- a/drivers/tty/sysrq.c
>>> +++ b/drivers/tty/sysrq.c
>>> @@ -548,9 +548,14 @@ void __handle_sysrq(int key, bool check_mask)
>>> ;
>>> if (j != i)
>>> continue;
>>> - printk("%s ", sysrq_key_table[i]->help_msg);
>>> + /* only print if handler is enabled */
>>> + if (sysrq_enabled & 1 ||
>>> + sysrq_enabled & sysrq_key_table[i]->enable_mask)
>>> + printk("%s ", sysrq_key_table[i]->help_msg);
>>> }
>>> }
>>> + if (!(sysrq_enabled & 1))
>>> + printk("(some options are disabled)");
>>> printk("\n");
>>> console_loglevel = orig_log_level;
>>> }
>>
>> What exactly is this fixing? What is broken here that this change
>> resolves? Where is it applicable? I need a lot more context here
>> please.
>
> Without this patch you get something like
> re[b]oot [r]aw [s]ync [h]elp ....
> even if none of these sysrq triggers are available because of the setting
> mask of
> kernel.sysrq
> With this patch then if (e.g.)
> kernel.sysrq = 16
> then you will only see
> [s]ync
> i.e. those commands you have privilege to issue via sysrq keypresses.
> Contact me if you need more,
> Shawn

But all operations are enabled when triggered via /proc/sysrq-trigger.
How about indicating key-disabled operations with a symbol instead?

Regards,
Peter Hurley



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