[PATCH 2.6.23] SysRq: print hotkey info while pressing undef key

[PATCH 2.6.23] SysRq: print hotkey info while pressing undef key

[Yi Yang]

For SysRq, we just can get hot key list from Documentation/sysrq.txt
, but in the most of cases, the user can't access it by hand on
using SysRq to debug, so it is better for SysRq to provide an online
help for the users.

SysRq has already provided a similiar help before this patch, but it
is not so definite that the user doesn't know what happened and how
to do on pressing an undefined hot key.

In addition, that funtion has a big loop with another big loop
embedded which is very inefficient, it is intended to skip some hot
key help info for such a function as "Changing Loglevel", just print
a help info for this, that is very unnecessary. In fact, the key '0'
 - '8' have different results the user should know.

This patch add this online help function, it'll print thw whole hot
key list and corresponding function descriptions, it can print the new
defined hot key without any changed needed.

The output is the below on pressing an undefined hot key:

SysRq : <6>this hot key isn't defined.

SysRq Help Information:

  Hot Key      Function Description
===========    ====================
ALT+SysRq+0    Changing Loglevel to this value
ALT+SysRq+1    Changing Loglevel to this value
ALT+SysRq+2    Changing Loglevel to this value
ALT+SysRq+3    Changing Loglevel to this value
ALT+SysRq+4    Changing Loglevel to this value
ALT+SysRq+5    Changing Loglevel to this value
ALT+SysRq+6    Changing Loglevel to this value
ALT+SysRq+7    Changing Loglevel to this value
ALT+SysRq+8    Changing Loglevel to this value
ALT+SysRq+9    Changing Loglevel to this value
ALT+SysRq+a    Not defined
ALT+SysRq+b    Resetting
ALT+SysRq+c    Trigger a crashdump
ALT+SysRq+d    Not defined
ALT+SysRq+e    Terminate All Tasks
ALT+SysRq+f    Manual OOM execution
ALT+SysRq+g    Not defined
ALT+SysRq+h    Not defined
ALT+SysRq+i    Kill All Tasks
ALT+SysRq+j    Not defined
ALT+SysRq+k    SAK
ALT+SysRq+l    Not defined
ALT+SysRq+m    Show Memory
ALT+SysRq+n    Nice All RT Tasks
ALT+SysRq+o    Power Off
ALT+SysRq+p    Show Regs
ALT+SysRq+q    Show Pending Timers
ALT+SysRq+r    Keyboard mode set to XLATE
ALT+SysRq+s    Emergency Sync
ALT+SysRq+t    Show State
ALT+SysRq+u    Emergency Remount R/O
ALT+SysRq+v    Not defined
ALT+SysRq+w    Show Blocked State
ALT+SysRq+x    Not defined
ALT+SysRq+y    Not defined
ALT+SysRq+z    Not defined

Signed-off-by: Yi Yang <yang.y.yi@gmail.com>
---
 sysrq.c |   38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

--- a/drivers/char/sysrq.c	2007-10-16 18:32:58.000000000 +0800
+++ b/drivers/char/sysrq.c	2007-10-16 23:21:59.000000000 +0800
@@ -45,6 +45,16 @@ int __read_mostly __sysrq_enabled = 1;
 
 static int __read_mostly sysrq_always_enabled;
 
+/*
+ * Hot key table SysRq supports
+ */
+static char __read_mostly sysrq_hot_key_table[36] = {
+	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+	'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
+	'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
+	'u', 'v', 'w', 'x', 'y', 'z'
+};
+
 int sysrq_on(void)
 {
 	return __sysrq_enabled || sysrq_always_enabled;
@@ -81,7 +91,7 @@ static void sysrq_handle_loglevel(int ke
 static struct sysrq_key_op sysrq_loglevel_op = {
 	.handler	= sysrq_handle_loglevel,
 	.help_msg	= "loglevel0-8",
-	.action_msg	= "Changing Loglevel",
+	.action_msg	= "Changing Loglevel to this value",
 	.enable_mask	= SYSRQ_ENABLE_LOG,
 };
 
@@ -410,7 +420,7 @@ void __handle_sysrq(int key, struct tty_
 	spin_lock_irqsave(&sysrq_key_table_lock, flags);
 	orig_log_level = console_loglevel;
 	console_loglevel = 7;
-	printk(KERN_INFO "SysRq : ");
+	printk(KERN_INFO "\nSysRq : ");
 
         op_p = __sysrq_get_key_op(key);
         if (op_p) {
@@ -426,18 +436,22 @@ void __handle_sysrq(int key, struct tty_
 			printk("This sysrq operation is disabled.\n");
 		}
 	} else {
-		printk("HELP : ");
-		/* Only print the help msg once per handler */
+		/*
+		 * Print SysRq hot key list
+		 */
+		printk(KERN_INFO "this hot key isn't defined.\n");
+		printk(KERN_INFO "\nSysRq Help Information:\n");
+		printk(KERN_INFO "\n  Hot Key      Function Description\n");
+		printk(KERN_INFO "===========    ====================\n");
 		for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
 			if (sysrq_key_table[i]) {
-				int j;
-
-				for (j = 0; sysrq_key_table[i] !=
-						sysrq_key_table[j]; j++)
-					;
-				if (j != i)
-					continue;
-				printk("%s ", sysrq_key_table[i]->help_msg);
+				printk(KERN_INFO "ALT+SysRq+%c    %s\n",
+					sysrq_hot_key_table[i],
+					sysrq_key_table[i]->action_msg);
+			} else {
+				printk(KERN_INFO "ALT+SysRq+%c    %s\n",
+					sysrq_hot_key_table[i],
+					"Not defined");
 			}
 		}
 		printk("\n");

Re: [PATCH 2.6.23] SysRq: print hotkey info while pressing undef key

[Andreas Schwab]

Yi Yang <yang.y.yi@gmail.com> writes:

> For SysRq, we just can get hot key list from Documentation/sysrq.txt
> , but in the most of cases, the user can't access it by hand on
> using SysRq to debug, so it is better for SysRq to provide an online
> help for the users.
>
> SysRq has already provided a similiar help before this patch, but it
> is not so definite that the user doesn't know what happened and how
> to do on pressing an undefined hot key.
>
> In addition, that funtion has a big loop with another big loop
> embedded which is very inefficient, it is intended to skip some hot
> key help info for such a function as "Changing Loglevel", just print
> a help info for this, that is very unnecessary. In fact, the key '0'
>  - '8' have different results the user should know.
>
> This patch add this online help function, it'll print thw whole hot
> key list and corresponding function descriptions, it can print the new
> defined hot key without any changed needed.
>
> The output is the below on pressing an undefined hot key:
>
> SysRq : <6>this hot key isn't defined.
          ^^^

This is misplaced.

> @@ -410,7 +420,7 @@ void __handle_sysrq(int key, struct tty_
>  	spin_lock_irqsave(&sysrq_key_table_lock, flags);
>  	orig_log_level = console_loglevel;
>  	console_loglevel = 7;
> -	printk(KERN_INFO "SysRq : ");
> +	printk(KERN_INFO "\nSysRq : ");

It does not make any sense to put the printk level just before the
newline, since the newline resets it to the default level.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: [PATCH 2.6.23] SysRq: print hotkey info while pressing undef key

[Pavel Machek]

Hi!

> For SysRq, we just can get hot key list from Documentation/sysrq.txt
> , but in the most of cases, the user can't access it by hand on
> using SysRq to debug, so it is better for SysRq to provide an online
> help for the users.
> 
> SysRq has already provided a similiar help before this patch, but it
> is not so definite that the user doesn't know what happened and how
> to do on pressing an undefined hot key.
> 
> In addition, that funtion has a big loop with another big loop
> embedded which is very inefficient, it is intended to skip some hot
> key help info for such a function as "Changing Loglevel", just print
> a help info for this, that is very unnecessary. In fact, the key '0'
>  - '8' have different results the user should know.
> 
> This patch add this online help function, it'll print thw whole hot
> key list and corresponding function descriptions, it can print the new
> defined hot key without any changed needed.
> 
> The output is the below on pressing an undefined hot key:
> 
> SysRq : <6>this hot key isn't defined.
> 
> SysRq Help Information:
> 
>   Hot Key      Function Description
> ===========    ====================
> ALT+SysRq+0    Changing Loglevel to this value
> ALT+SysRq+1    Changing Loglevel to this value
> ALT+SysRq+2    Changing Loglevel to this value
> ALT+SysRq+3    Changing Loglevel to this value
> ALT+SysRq+4    Changing Loglevel to this value
> ALT+SysRq+5    Changing Loglevel to this value
> ALT+SysRq+6    Changing Loglevel to this value
> ALT+SysRq+7    Changing Loglevel to this value
> ALT+SysRq+8    Changing Loglevel to this value
> ALT+SysRq+9    Changing Loglevel to this value
> ALT+SysRq+a    Not defined
> ALT+SysRq+b    Resetting
> ALT+SysRq+c    Trigger a crashdump
> ALT+SysRq+d    Not defined
> ALT+SysRq+e    Terminate All Tasks
> ALT+SysRq+f    Manual OOM execution
> ALT+SysRq+g    Not defined
> ALT+SysRq+h    Not defined
> ALT+SysRq+i    Kill All Tasks
> ALT+SysRq+j    Not defined
> ALT+SysRq+k    SAK
> ALT+SysRq+l    Not defined
> ALT+SysRq+m    Show Memory
> ALT+SysRq+n    Nice All RT Tasks
> ALT+SysRq+o    Power Off
> ALT+SysRq+p    Show Regs
> ALT+SysRq+q    Show Pending Timers
> ALT+SysRq+r    Keyboard mode set to XLATE
> ALT+SysRq+s    Emergency Sync
> ALT+SysRq+t    Show State
> ALT+SysRq+u    Emergency Remount R/O
> ALT+SysRq+v    Not defined
> ALT+SysRq+w    Show Blocked State
> ALT+SysRq+x    Not defined
> ALT+SysRq+y    Not defined
> ALT+SysRq+z    Not defined

This will scroll out of users view on small terminals.

Plus it is untrue. On sparc, it is stop+x, not sysrq+x.

> +/*
> + * Hot key table SysRq supports
> + */
> +static char __read_mostly sysrq_hot_key_table[36] = {
> +	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
> +	'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
> +	'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
> +	'u', 'v', 'w', 'x', 'y', 'z'
> +};

Plus this is practically guaranteed to get out of sync with
reality. If you did this to make sysrq printing faster... then that is
very bad optimization.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2.6.23] SysRq: print hotkey info while pressing undef key

[Yi Yang]

Andreas Schwab 写道:
> Yi Yang <yang.y.yi@gmail.com> writes:
>
>   
>> For SysRq, we just can get hot key list from Documentation/sysrq.txt
>> , but in the most of cases, the user can't access it by hand on
>> using SysRq to debug, so it is better for SysRq to provide an online
>> help for the users.
>>
>> SysRq has already provided a similiar help before this patch, but it
>> is not so definite that the user doesn't know what happened and how
>> to do on pressing an undefined hot key.
>>
>> In addition, that funtion has a big loop with another big loop
>> embedded which is very inefficient, it is intended to skip some hot
>> key help info for such a function as "Changing Loglevel", just print
>> a help info for this, that is very unnecessary. In fact, the key '0'
>>  - '8' have different results the user should know.
>>
>> This patch add this online help function, it'll print thw whole hot
>> key list and corresponding function descriptions, it can print the new
>> defined hot key without any changed needed.
>>
>> The output is the below on pressing an undefined hot key:
>>
>> SysRq : <6>this hot key isn't defined.
>>     
>           ^^^
>
> This is misplaced.
>   

printk(KERN_INFO "SysRq : \n") can fix it.

>   
>> @@ -410,7 +420,7 @@ void __handle_sysrq(int key, struct tty_
>>  	spin_lock_irqsave(&sysrq_key_table_lock, flags);
>>  	orig_log_level = console_loglevel;
>>  	console_loglevel = 7;
>> -	printk(KERN_INFO "SysRq : ");
>> +	printk(KERN_INFO "\nSysRq : ");
>>     
>
> It does not make any sense to put the printk level just before the
> newline, since the newline resets it to the default level.
>   
Thank you, I'll remove \n.
> Andreas.
>
>   

Re: [PATCH 2.6.23] SysRq: print hotkey info while pressing undef key

[Yi Yang]

Pavel Machek 写道:
> Hi!
>
>   
>> For SysRq, we just can get hot key list from Documentation/sysrq.txt
>> , but in the most of cases, the user can't access it by hand on
>> using SysRq to debug, so it is better for SysRq to provide an online
>> help for the users.
>>
>> SysRq has already provided a similiar help before this patch, but it
>> is not so definite that the user doesn't know what happened and how
>> to do on pressing an undefined hot key.
>>
>> In addition, that funtion has a big loop with another big loop
>> embedded which is very inefficient, it is intended to skip some hot
>> key help info for such a function as "Changing Loglevel", just print
>> a help info for this, that is very unnecessary. In fact, the key '0'
>>  - '8' have different results the user should know.
>>
>> This patch add this online help function, it'll print thw whole hot
>> key list and corresponding function descriptions, it can print the new
>> defined hot key without any changed needed.
>>
>> The output is the below on pressing an undefined hot key:
>>
>> SysRq : <6>this hot key isn't defined.
>>
>> SysRq Help Information:
>>
>>   Hot Key      Function Description
>> ===========    ====================
>> ALT+SysRq+0    Changing Loglevel to this value
>> ALT+SysRq+1    Changing Loglevel to this value
>> ALT+SysRq+2    Changing Loglevel to this value
>> ALT+SysRq+3    Changing Loglevel to this value
>> ALT+SysRq+4    Changing Loglevel to this value
>> ALT+SysRq+5    Changing Loglevel to this value
>> ALT+SysRq+6    Changing Loglevel to this value
>> ALT+SysRq+7    Changing Loglevel to this value
>> ALT+SysRq+8    Changing Loglevel to this value
>> ALT+SysRq+9    Changing Loglevel to this value
>> ALT+SysRq+a    Not defined
>> ALT+SysRq+b    Resetting
>> ALT+SysRq+c    Trigger a crashdump
>> ALT+SysRq+d    Not defined
>> ALT+SysRq+e    Terminate All Tasks
>> ALT+SysRq+f    Manual OOM execution
>> ALT+SysRq+g    Not defined
>> ALT+SysRq+h    Not defined
>> ALT+SysRq+i    Kill All Tasks
>> ALT+SysRq+j    Not defined
>> ALT+SysRq+k    SAK
>> ALT+SysRq+l    Not defined
>> ALT+SysRq+m    Show Memory
>> ALT+SysRq+n    Nice All RT Tasks
>> ALT+SysRq+o    Power Off
>> ALT+SysRq+p    Show Regs
>> ALT+SysRq+q    Show Pending Timers
>> ALT+SysRq+r    Keyboard mode set to XLATE
>> ALT+SysRq+s    Emergency Sync
>> ALT+SysRq+t    Show State
>> ALT+SysRq+u    Emergency Remount R/O
>> ALT+SysRq+v    Not defined
>> ALT+SysRq+w    Show Blocked State
>> ALT+SysRq+x    Not defined
>> ALT+SysRq+y    Not defined
>> ALT+SysRq+z    Not defined
>>     
>
> This will scroll out of users view on small terminals.
>
> Plus it is untrue. On sparc, it is stop+x, not sysrq+x.
>
>   
You're right, it it better to remove ALT+SysRq
>> +/*
>> + * Hot key table SysRq supports
>> + */
>> +static char __read_mostly sysrq_hot_key_table[36] = {
>> +	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
>> +	'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
>> +	'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
>> +	'u', 'v', 'w', 'x', 'y', 'z'
>> +};
>>     
>
> Plus this is practically guaranteed to get out of sync with
> reality. If you did this to make sysrq printing faster... then that is
> very bad optimization.
> 									Pavel
>   
This char array is just for output, thees are jsut the keys sysrq has 
defined, in the current
design of sysrq, to add a new key is not easy unless you use an existed 
but unused key,
so this has no problem.

SysRq is just for debugging or emergent handling, so this array is 
impossible to result in
any bad effects, it is just for convenience.