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SubjectRe: Magic SysRq +# in 2.4.9-ac/2.4.10-pre12
Alan Cox wrote:
>
> > Anyway, in looking at SysRq loglevel handling in
> > 2.4.9-ac (and 2.4.10-pre12), I see that it has been modified
> > quite a bit. Looks extensible, which can be good.
> > However, looking over it gave me several nagging questions
> > and problems.
> >
> > If someone (Crutcher ?) wants to patch it, that's fine.
> > If I patched it, I would just add a
> > next_loglevel = -1;
> > at the beginning of __handle_sysrq_nolock() and then
> > let the loglevel handler(s) set next_loglevel.
> > If next_loglevel != -1 at the end of __handle_sysrq_nolock(),
> > set console_loglevel to next_loglevel.
>
> Send me a patch and cc Linus/Crutcher

Here's a patch to fix SysRq handling of console_loglevel.

Please apply to 2.4.10-pre12 and to 2.4.9-ac12.

Thanks,
~Randy--- linux/drivers/char/sysrq.c.org Mon Sep 17 10:15:48 2001
+++ linux/drivers/char/sysrq.c Wed Sep 19 10:15:12 2001
@@ -39,6 +39,8 @@
/* Whether we react on sysrq keys or just ignore them */
int sysrq_enabled = 1;

+static int entry_loglevel, next_loglevel;
+
/* Machine specific power off function */
void (*sysrq_power_off)(void);

@@ -47,13 +49,13 @@
struct kbd_struct *kbd, struct tty_struct *tty) {
int i;
i = key - '0';
- console_loglevel = 7;
printk("%d\n", i);
- console_loglevel = i;
-}
+ next_loglevel = i;
+}
+
static struct sysrq_key_op sysrq_loglevel_op = {
handler: sysrq_handle_loglevel,
- help_msg: "loglevel0-8",
+ help_msg: "loglevel0-9",
action_msg: "Loglevel set to ",
};

@@ -66,6 +68,7 @@
do_SAK(tty);
reset_vc(fg_console);
}
+
static struct sysrq_key_op sysrq_SAK_op = {
handler: sysrq_handle_SAK,
help_msg: "saK",
@@ -137,9 +140,6 @@
/* do_emergency_sync helper function */
static void go_sync(struct super_block *sb, int remount_flag)
{
- int orig_loglevel;
- orig_loglevel = console_loglevel;
- console_loglevel = 7;
printk(KERN_INFO "%sing device %s ... ",
remount_flag ? "Remount" : "Sync",
kdevname(sb->s_dev));
@@ -178,7 +178,6 @@
fsync_dev(sb->s_dev);
printk("OK\n");
}
- console_loglevel = orig_loglevel;
}
/*
* Emergency Sync or Unmount. We cannot do it directly, so we set a special
@@ -192,7 +191,6 @@
void do_emergency_sync(void) {
struct super_block *sb;
int remount_flag;
- int orig_loglevel;

lock_kernel();
remount_flag = (emergency_sync_scheduled == EMERG_REMOUNT);
@@ -211,11 +209,7 @@
go_sync(sb, remount_flag);

unlock_kernel();
-
- orig_loglevel = console_loglevel;
- console_loglevel = 7;
printk(KERN_INFO "Done.\n");
- console_loglevel = orig_loglevel;
}

static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
@@ -223,6 +217,7 @@
emergency_sync_scheduled = EMERG_SYNC;
wakeup_bdflush(0);
}
+
static struct sysrq_key_op sysrq_sync_op = {
handler: sysrq_handle_sync,
help_msg: "Sync",
@@ -250,6 +245,7 @@
if (pt_regs)
show_regs(pt_regs);
}
+
static struct sysrq_key_op sysrq_showregs_op = {
handler: sysrq_handle_showregs,
help_msg: "showPc",
@@ -261,6 +257,7 @@
struct kbd_struct *kbd, struct tty_struct *tty) {
show_state();
}
+
static struct sysrq_key_op sysrq_showstate_op = {
handler: sysrq_handle_showstate,
help_msg: "showTasks",
@@ -272,6 +269,7 @@
struct kbd_struct *kbd, struct tty_struct *tty) {
show_mem();
}
+
static struct sysrq_key_op sysrq_showmem_op = {
handler: sysrq_handle_showmem,
help_msg: "showMem",
@@ -303,8 +301,9 @@
static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
struct kbd_struct *kbd, struct tty_struct *tty) {
send_sig_all(SIGTERM, 0);
- console_loglevel = 8;
+ next_loglevel = 8;
}
+
static struct sysrq_key_op sysrq_term_op = {
handler: sysrq_handle_term,
help_msg: "tErm",
@@ -314,8 +313,9 @@
static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
struct kbd_struct *kbd, struct tty_struct *tty) {
send_sig_all(SIGKILL, 0);
- console_loglevel = 8;
+ next_loglevel = 8;
}
+
static struct sysrq_key_op sysrq_kill_op = {
handler: sysrq_handle_kill,
help_msg: "kIll",
@@ -325,8 +325,9 @@
static void sysrq_handle_killall(int key, struct pt_regs *pt_regs,
struct kbd_struct *kbd, struct tty_struct *tty) {
send_sig_all(SIGKILL, 1);
- console_loglevel = 8;
+ next_loglevel = 8;
}
+
static struct sysrq_key_op sysrq_killall_op = {
handler: sysrq_handle_killall,
help_msg: "killalL",
@@ -381,7 +382,7 @@
/* v */ NULL,
/* w */ NULL,
/* x */ NULL,
-/* w */ NULL,
+/* y */ NULL,
/* z */ NULL
};

@@ -434,6 +435,7 @@

void handle_sysrq(int key, struct pt_regs *pt_regs,
struct kbd_struct *kbd, struct tty_struct *tty) {
+
if (!sysrq_enabled)
return;

@@ -451,13 +453,13 @@
void __handle_sysrq_nolock(int key, struct pt_regs *pt_regs,
struct kbd_struct *kbd, struct tty_struct *tty) {
struct sysrq_key_op *op_p;
- int orig_log_level;
int i, j;

if (!sysrq_enabled)
return;

- orig_log_level = console_loglevel;
+ entry_loglevel = console_loglevel;
+ next_loglevel = -1;
console_loglevel = 7;
printk(KERN_INFO "SysRq : ");

@@ -476,7 +478,7 @@
}
printk ("\n");
}
- console_loglevel = orig_log_level;
+ console_loglevel = (next_loglevel == -1) ? entry_loglevel : next_loglevel;
}

EXPORT_SYMBOL(handle_sysrq);
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