Re: [PATCH] console logging detour via printk
From: Samo Pogacnik
Date: Sat May 01 2010 - 18:23:44 EST
Dne 30.04.2010 (pet) ob 15:45 -0700 je Randy Dunlap zapisal(a):
> On Sat, 01 May 2010 00:03:00 +0200 Samo Pogacnik wrote:
>
> > Hi,
>
> > diff --git a_linux-2.6.33.3/drivers/char/Kconfig b_linux-2.6.33.3/drivers/char/Kconfig
> > index e023682..b5d0909 100644
> > --- a_linux-2.6.33.3/drivers/char/Kconfig
> > +++ b_linux-2.6.33.3/drivers/char/Kconfig
> > @@ -66,6 +66,23 @@ config VT_CONSOLE
> >
> > If unsure, say Y.
> >
> > +config VT_CONSOLE_DETOUR
> > + bool "Support for VT console detour via printk"
> > + depends on VT_CONSOLE
> > + default n
> > + ---help---
> > + If you do say Y here, the support for writing console messages via
>
> If you say Y here,
>
> > + printk is included into VT console code.
> > +
> > + The feature is usefull to catch all console log. In order to use this
>
> useful log messages.
>
> > + feature, you should specify kernel command line option "detour" or write a
> > + positive number into /proc/sys/kernel/console_detour. You can disable
> > + the feature on-line by writing zero into the proc file. By writing a
> > + negative value into the proc file, the feature is disabled permanently
> > + (until next boot).
> > +
> > + If unsure, say N.
> > +
> > config HW_CONSOLE
> > bool
> > depends on VT && !S390 && !UML
>
> > diff --git a_linux-2.6.33.3/drivers/serial/Kconfig b_linux-2.6.33.3/drivers/serial/Kconfig
> > index 9ff47db..20acfab 100644
> > --- a_linux-2.6.33.3/drivers/serial/Kconfig
> > +++ b_linux-2.6.33.3/drivers/serial/Kconfig
> > @@ -1031,6 +1031,23 @@ config SERIAL_CORE
> > config SERIAL_CORE_CONSOLE
> > bool
> >
> > +config SERIAL_CORE_CONSOLE_DETOUR
> > + bool "Support for serial console detour via printk"
> > + depends on SERIAL_CORE_CONSOLE
> > + default n
> > + ---help---
> > + If you do say Y here, the support for writing console messages via
>
> If you say Y here,
>
> > + printk is included into serial console code.
> > +
> > + The feature is usefull to catch all console log. In order to use this
>
> useful log messages.
>
> > + feature, you should specify kernel command line option "detour" or write a
> > + positive number into /proc/sys/kernel/console_detour. You can disable
> > + the feature on-line by writing zero into the proc file. By writing a
> > + negative value into the proc file, the feature is disabled permanently
> > + (until next boot).
> > +
> > + If unsure, say N.
> > +
>
> The kernel command line option needs to be added to Documentation/kernel-parameters.txt
> also, please.
>
> > config CONSOLE_POLL
> > bool
> >
> > diff --git a_linux-2.6.33.3/include/linux/console.h b_linux-2.6.33.3/include/linux/console.h
> > index dcca533..bc88030 100644
> > --- a_linux-2.6.33.3/include/linux/console.h
> > +++ b_linux-2.6.33.3/include/linux/console.h
> > @@ -108,6 +108,12 @@ struct console {
> > struct console *next;
> > };
> >
> > +extern int console_detour;
> > +extern void console_printk_detour(const unsigned char *, int);
>
> Please include parameter names in function prototype(s).
>
> > +
> > +struct ctl_table;
> > +int detour_sysctl_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
>
> ditto
>
> > +
> > extern int console_set_on_cmdline;
> >
> > extern int add_preferred_console(char *name, int idx, char *options);
>
>
> Looks interesting/useful to me. Thanks.
>
> ---
> ~Randy
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
Hi,
Here is the updated patch providing your hints and generalized for any
console type.
regards, Samo
---
Signed-off-by: Samo Pogacnik <samo_pogacnik@xxxxxxx>
diff --git a_linux-2.6.33.3/Documentation/kernel-parameters.txt b_linux-2.6.33.3/Documentation/kernel-parameters.txt
index e2c7487..ab0072c 100644
--- a_linux-2.6.33.3/Documentation/kernel-parameters.txt
+++ b_linux-2.6.33.3/Documentation/kernel-parameters.txt
@@ -628,6 +628,8 @@ and is between 256 and 4096 characters. It is defined in the file
Defaults to the default architecture's huge page size
if not specified.
+ detour [KNL] Enable console logging detour via printk.
+
dhash_entries= [KNL]
Set number of hash buckets for dentry cache.
diff --git a_linux-2.6.33.3/drivers/char/Kconfig b_linux-2.6.33.3/drivers/char/Kconfig
index e023682..43c552e 100644
--- a_linux-2.6.33.3/drivers/char/Kconfig
+++ b_linux-2.6.33.3/drivers/char/Kconfig
@@ -88,6 +88,22 @@ config VT_HW_CONSOLE_BINDING
information. For framebuffer console users, please refer to
<file:Documentation/fb/fbcon.txt>.
+config CONSOLE_DETOUR
+ bool "Support for console detour via printk"
+ default n
+ ---help---
+ If you say Y here, the support for writing console messages via
+ printk is included into the console code.
+
+ The feature is useful to catch all console log messages.
+ In order to use this feature, you should specify kernel command line
+ option "detour" or write a positive number into
+ /proc/sys/kernel/console_detour. You can disable the feature on-line
+ by writing zero into the proc file. By writing a negative value into
+ the proc file, the feature is disabled permanently (until next boot).
+
+ If unsure, say N.
+
config DEVKMEM
bool "/dev/kmem virtual device support"
default y
diff --git a_linux-2.6.33.3/drivers/char/tty_io.c b_linux-2.6.33.3/drivers/char/tty_io.c
index 76253cf..f77de34 100644
--- a_linux-2.6.33.3/drivers/char/tty_io.c
+++ b_linux-2.6.33.3/drivers/char/tty_io.c
@@ -1087,6 +1087,13 @@ ssize_t redirected_tty_write(struct file *file, const char __user *buf,
}
spin_unlock(&redirect_lock);
+#ifdef CONFIG_CONSOLE_DETOUR
+ if (console_detour) {
+ console_printk_detour(buf, count);
+ if (!p)
+ return count;
+ }
+#endif
if (p) {
ssize_t res;
res = vfs_write(p, buf, count, &p->f_pos);
diff --git a_linux-2.6.33.3/include/linux/console.h b_linux-2.6.33.3/include/linux/console.h
index dcca533..354a7a8 100644
--- a_linux-2.6.33.3/include/linux/console.h
+++ b_linux-2.6.33.3/include/linux/console.h
@@ -108,6 +108,13 @@ struct console {
struct console *next;
};
+extern int console_detour;
+extern void console_printk_detour(const unsigned char *buf, int count);
+
+struct ctl_table;
+int detour_sysctl_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos);
+
extern int console_set_on_cmdline;
extern int add_preferred_console(char *name, int idx, char *options);
diff --git a_linux-2.6.33.3/init/main.c b_linux-2.6.33.3/init/main.c
index 512ba15..add9e95 100644
--- a_linux-2.6.33.3/init/main.c
+++ b_linux-2.6.33.3/init/main.c
@@ -25,6 +25,7 @@
#include <linux/bootmem.h>
#include <linux/acpi.h>
#include <linux/tty.h>
+#include <linux/console.h>
#include <linux/gfp.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
@@ -249,6 +250,14 @@ static int __init loglevel(char *str)
early_param("loglevel", loglevel);
+static int __init detour(char *str)
+{
+ console_detour = 1;
+ return 0;
+}
+
+early_param("detour", detour);
+
/*
* Unknown boot options get handed to init, unless they look like
* unused parameters (modprobe will find them in /proc/cmdline).
diff --git a_linux-2.6.33.3/kernel/printk.c b_linux-2.6.33.3/kernel/printk.c
index 1751c45..953c6ea 100644
--- a_linux-2.6.33.3/kernel/printk.c
+++ b_linux-2.6.33.3/kernel/printk.c
@@ -1368,6 +1368,51 @@ static int __init disable_boot_consoles(void)
}
late_initcall(disable_boot_consoles);
+/*
+ * This option can be enabled with kernel command line option "detour" or
+ * through a proc file (/proc/sys/kernel/console_detour). It enables console
+ * logging through printk, if supported by enabled console.
+ */
+int console_detour;
+EXPORT_SYMBOL(console_detour);
+
+#define DETOUR_STR_SIZE 512
+void console_printk_detour(const unsigned char *buf, int count)
+{
+ char tmp[DETOUR_STR_SIZE + 1];
+
+ do {
+ if (count > DETOUR_STR_SIZE) {
+ memcpy(tmp, buf, DETOUR_STR_SIZE);
+ tmp[DETOUR_STR_SIZE] = '\0';
+ } else {
+ memcpy(tmp, buf, count);
+ tmp[count] = '\0';
+ }
+ count -= DETOUR_STR_SIZE;
+ printk(KERN_INFO "%s", tmp);
+ } while (count > 0);
+}
+EXPORT_SYMBOL(console_printk_detour);
+
+int detour_sysctl_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos)
+{
+ static int disable_forever;
+
+ proc_dointvec(table, write, buffer, length, ppos);
+ if (write) {
+ if ((console_detour < 0) || (disable_forever != 0)) {
+ disable_forever = 1;
+ console_detour = 0;
+ return 0;
+ }
+ if (console_detour > 1)
+ console_detour = 1;
+ }
+ return 0;
+}
+
#if defined CONFIG_PRINTK
/*
diff --git a_linux-2.6.33.3/kernel/sysctl.c b_linux-2.6.33.3/kernel/sysctl.c
index 8a68b24..ab644cb 100644
--- a_linux-2.6.33.3/kernel/sysctl.c
+++ b_linux-2.6.33.3/kernel/sysctl.c
@@ -50,6 +50,7 @@
#include <linux/ftrace.h>
#include <linux/slow-work.h>
#include <linux/perf_event.h>
+#include <linux/console.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@@ -936,6 +937,13 @@ static struct ctl_table kern_table[] = {
.proc_handler = proc_dointvec,
},
#endif
+ {
+ .procname = "console_detour",
+ .data = &console_detour,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &detour_sysctl_handler,
+ },
/*
* NOTE: do not add new entries to this table unless you have read
* Documentation/sysctl/ctl_unnumbered.txt
--
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