[PATCH] sysrq: showBlockedTasks is sysrq-W

Change SysRq showBlockedTasks from sysrq-X to sysrq-W and show that in the Help message. It was previously done via X, but X is already used for Xmon on ppc & powerpc platforms and this collision needs to be avoided. All callers of register_sysrq_key() are now marked in the sysrq op/key table. I didn't mark 'h' as Help because Help is just printed for any unknown key, such as '?'. Added some omitted sysrq key entries in the sysrq.txt file.

Randy Dunlap committed 19 years ago

Commit d346cce1 parent 7d895242 files · +46 −40Browse files

Unified · Split

2 files

Documentation/sysrq.txt +35 −31
drivers/char/sysrq.c +11 −9

Documentation/sysrq.txt+35−31

@@ -1,6 +1,6 @@
1	1	Linux Magic System Request Key Hacks
2		−Documentation for sysrq.c version 1.15
3		−Last update: $Date: 2001/01/28 10:15:59 $
	2	+Documentation for sysrq.c
	3	+Last update: 2007-JAN-06
4	4
5	5	* What is the magic SysRq key?
6	6	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -35,7 +35,7 @@ You can set the value in the file by the following command: · 28 unmodified lines
35	35
36	36	Note that the value of /proc/sys/kernel/sysrq influences only the invocation
37	37	via a keyboard. Invocation of any operation via /proc/sysrq-trigger is always
38		−allowed.
	38	+allowed (by a user with admin privileges).
39	39
40	40	* How do I use the magic SysRq key?
41	41	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -58,7 +58,7 @@ On PowerPC - Press 'ALT - Print Screen (or F13) - <command key>, · 16 unmodified lines
58	58	On other - If you know of the key combos for other architectures, please
59	59	let me know so I can add them to this section.
60	60
61		−On all - write a character to /proc/sysrq-trigger. eg:
	61	+On all - write a character to /proc/sysrq-trigger. e.g.:
62	62
63	63	echo t > /proc/sysrq-trigger
64	64
@@ -74,6 +74,8 @@ On all - write a character to /proc/sysrq-trigger. eg: · 9 unmodified lines
74	74
75	75	'c' - Will perform a kexec reboot in order to take a crashdump.
76	76
	77	+'d' - Shows all locks that are held.
	78	+
77	79	'o' - Will shut your system off (if configured and supported).
78	80
79	81	's' - Will attempt to sync all mounted filesystems.
@@ -87,38 +89,43 @@ On all - write a character to /proc/sysrq-trigger. eg: · 7 unmodified lines
87	89
88	90	'm' - Will dump current memory info to your console.
89	91
	92	+'n' - Used to make RT tasks nice-able
	93	+
90	94	'v' - Dumps Voyager SMP processor info to your console.
91	95
	96	+'w' - Dumps tasks that are in uninterruptable (blocked) state.
	97	+
	98	+'x' - Used by xmon interface on ppc/powerpc platforms.
	99	+
92	100	'0'-'9' - Sets the console log level, controlling which kernel messages
93	101	will be printed to your console. ('0', for example would make
94	102	it so that only emergency messages like PANICs or OOPSes would
95	103	make it to your console.)
96	104
97		−'f' - Will call oom_kill to kill a memory hog process
	105	+'f' - Will call oom_kill to kill a memory hog process.
98	106
99	107	'e' - Send a SIGTERM to all processes, except for init.
100	108
101		−'i' - Send a SIGKILL to all processes, except for init.
	109	+'g' - Used by kgdb on ppc platforms.
102	110
103		−'l' - Send a SIGKILL to all processes, INCLUDING init. (Your system
104		− will be non-functional after this.)
	111	+'i' - Send a SIGKILL to all processes, except for init.
105	112
106		−'h' - Will display help ( actually any other key than those listed
	113	+'h' - Will display help (actually any other key than those listed
107	114	above will display help. but 'h' is easy to remember :-)
108	115
109	116	* Okay, so what can I use them for?
110	117	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
111	118	Well, un'R'aw is very handy when your X server or a svgalib program crashes.
112	119
113		−sa'K' (Secure Access Key) is useful when you want to be sure there are no
114		−trojan program is running at console and which could grab your password
115		−when you would try to login. It will kill all programs on given console
116		−and thus letting you make sure that the login prompt you see is actually
	120	+sa'K' (Secure Access Key) is useful when you want to be sure there is no
	121	+trojan program running at console which could grab your password
	122	+when you would try to login. It will kill all programs on given console,
	123	+thus letting you make sure that the login prompt you see is actually
117	124	the one from init, not some trojan program.
118	125	IMPORTANT: In its true form it is not a true SAK like the one in a :IMPORTANT
119	126	IMPORTANT: c2 compliant system, and it should not be mistaken as :IMPORTANT
120	127	IMPORTANT: such. :IMPORTANT
121		− It seems other find it useful as (System Attention Key) which is
	128	+ It seems others find it useful as (System Attention Key) which is
122	129	useful when you want to exit a program that will not let you switch consoles.
123	130	(For example, X or a svgalib program.)
124	131
@@ -139,8 +146,8 @@ OK or Done message...) · 14 unmodified lines
139	146	Again, the unmount (remount read-only) hasn't taken place until you see the
140	147	"OK" and "Done" message appear on the screen.
141	148
142		−The loglevel'0'-'9' is useful when your console is being flooded with
143		−kernel messages you do not want to see. Setting '0' will prevent all but
	149	+The loglevels '0'-'9' are useful when your console is being flooded with
	150	+kernel messages you do not want to see. Selecting '0' will prevent all but
144	151	the most urgent kernel messages from reaching your console. (They will
145	152	still be logged if syslogd/klogd are alive, though.)
146	153
@@ -152,7 +159,7 @@ processes. · 5 unmodified lines
152	159	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
153	160	That happens to me, also. I've found that tapping shift, alt, and control
154	161	on both sides of the keyboard, and hitting an invalid sysrq sequence again
155		−will fix the problem. (ie, something like alt-sysrq-z). Switching to another
	162	+will fix the problem. (i.e., something like alt-sysrq-z). Switching to another
156	163	virtual console (ALT+Fn) and then back again should also help.
157	164
158	165	* I hit SysRq, but nothing seems to happen, what's wrong?
@@ -174,11 +181,11 @@ handler function you will use, B) a help_msg string, that will print when SysRQ · 15 unmodified lines
174	181	prints help, and C) an action_msg string, that will print right before your
175	182	handler is called. Your handler must conform to the prototype in 'sysrq.h'.
176	183
177		−After the sysrq_key_op is created, you can call the macro
178		−register_sysrq_key(int key, struct sysrq_key_op *op_p) that is defined in
179		−sysrq.h, this will register the operation pointed to by 'op_p' at table
180		−key 'key', if that slot in the table is blank. At module unload time, you must
181		−call the macro unregister_sysrq_key(int key, struct sysrq_key_op *op_p), which
	184	+After the sysrq_key_op is created, you can call the kernel function
	185	+register_sysrq_key(int key, struct sysrq_key_op *op_p); this will
	186	+register the operation pointed to by 'op_p' at table key 'key',
	187	+if that slot in the table is blank. At module unload time, you must call
	188	+the function unregister_sysrq_key(int key, struct sysrq_key_op *op_p), which
182	189	will remove the key op pointed to by 'op_p' from the key 'key', if and only if
183	190	it is currently registered in that slot. This is in case the slot has been
184	191	overwritten since you registered it.
@@ -186,15 +193,12 @@ overwritten since you registered it. · 1 unmodified line
186	193	The Magic SysRQ system works by registering key operations against a key op
187	194	lookup table, which is defined in 'drivers/char/sysrq.c'. This key table has
188	195	a number of operations registered into it at compile time, but is mutable,
189		−and 4 functions are exported for interface to it: __sysrq_lock_table,
190		−__sysrq_unlock_table, __sysrq_get_key_op, and __sysrq_put_key_op. The
191		−functions __sysrq_swap_key_ops and __sysrq_swap_key_ops_nolock are defined
192		−in the header itself, and the REGISTER and UNREGISTER macros are built from
193		−these. More complex (and dangerous!) manipulations of the table are possible
194		−using these functions, but you must be careful to always lock the table before
195		−you read or write from it, and to unlock it again when you are done. (And of
196		−course, to never ever leave an invalid pointer in the table). Null pointers in
197		−the table are always safe :)
	196	+and 2 functions are exported for interface to it:
	197	+ register_sysrq_key and unregister_sysrq_key.
	198	+Of course, never ever leave an invalid pointer in the table. I.e., when
	199	+your module that called register_sysrq_key() exits, it must call
	200	+unregister_sysrq_key() to clean up the sysrq key table entry that it used.
	201	+Null pointers in the table are always safe. :)
198	202
199	203	If for some reason you feel the need to call the handle_sysrq function from
200	204	within a function called by handle_sysrq, you must be aware that you are in

drivers/char/sysrq.c+11−9

@@ -215,7 +215,7 @@ static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty) · 214 unmodified lines
215	215	}
216	216	static struct sysrq_key_op sysrq_showstate_blocked_op = {
217	217	.handler = sysrq_handle_showstate_blocked,
218		− .help_msg = "showBlockedTasks",
	218	+ .help_msg = "shoW-blocked-tasks",
219	219	.action_msg = "Show Blocked State",
220	220	.enable_mask = SYSRQ_ENABLE_DUMP,
221	221	};
@@ -315,15 +315,16 @@ static struct sysrq_key_op *sysrq_key_table[36] = { · 93 unmodified lines
315	315	&sysrq_loglevel_op, /* 9 */
316	316
317	317	/*
318		− * Don't use for system provided sysrqs, it is handled specially on
319		− * sparc and will never arrive
	318	+ * a: Don't use for system provided sysrqs, it is handled specially on
	319	+ * sparc and will never arrive.
320	320	*/
321	321	NULL, /* a */
322	322	&sysrq_reboot_op, /* b */
323		− &sysrq_crashdump_op, /* c */
	323	+ &sysrq_crashdump_op, /* c & ibm_emac driver debug */
324	324	&sysrq_showlocks_op, /* d */
325	325	&sysrq_term_op, /* e */
326	326	&sysrq_moom_op, /* f */
	327	+ /* g: May be registered by ppc for kgdb */
327	328	NULL, /* g */
328	329	NULL, /* h */
329	330	&sysrq_kill_op, /* i */
@@ -332,18 +333,19 @@ static struct sysrq_key_op *sysrq_key_table[36] = { · 2 unmodified lines
332	333	NULL, /* l */
333	334	&sysrq_showmem_op, /* m */
334	335	&sysrq_unrt_op, /* n */
335		− /* This will often be registered as 'Off' at init time */
	336	+ /* o: This will often be registered as 'Off' at init time */
336	337	NULL, /* o */
337	338	&sysrq_showregs_op, /* p */
338	339	NULL, /* q */
339		− &sysrq_unraw_op, /* r */
	340	+ &sysrq_unraw_op, /* r */
340	341	&sysrq_sync_op, /* s */
341	342	&sysrq_showstate_op, /* t */
342	343	&sysrq_mountro_op, /* u */
343		− /* May be assigned at init time by SMP VOYAGER */
	344	+ /* v: May be registered at init time by SMP VOYAGER */
344	345	NULL, /* v */
345		− NULL, /* w */
346		− &sysrq_showstate_blocked_op, /* x */
	346	+ &sysrq_showstate_blocked_op, /* w */
	347	+ /* x: May be registered on ppc/powerpc for xmon */
	348	+ NULL, /* x */
347	349	NULL, /* y */
348	350	NULL /* z */
349	351	};