* [PATCH v4] console: allow log level threshold adjustments
@ 2016-12-12 10:16 Jan Beulich
2016-12-12 10:26 ` Wei Liu
2016-12-12 10:51 ` Andrew Cooper
0 siblings, 2 replies; 3+ messages in thread
From: Jan Beulich @ 2016-12-12 10:16 UTC (permalink / raw)
To: xen-devel
Cc: Stefano Stabellini, Wei Liu, George Dunlap, Andrew Cooper,
Ian Jackson, Tim Deegan
[-- Attachment #1: Type: text/plain, Size: 3383 bytes --]
... from serial console so that one doesn't always need to reboot to
see more / less messages.
Note that upper thresholds are sticky, i.e. while they get adjusted
upwards when the lower threshold would otherwise end up above the upper
one, they don't get adjusted when reducing the lower one. Full
flexibility is available only via a future sysctl interface.
Note further that (meaningless) large threshold values aren't being
rejected, for the sake of not adding more checks to the code than are
really necessary for safe operation.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v4: Split out sysctl.
v3: Mention apparently missing threshold upper bound checks in
description. Make flask_sysctl() accept the new operation.
v2: Add sysctl.
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -175,7 +175,7 @@ static void __init parse_guest_loglvl(ch
_parse_loglvl(s, &xenlog_guest_lower_thresh, &xenlog_guest_upper_thresh);
}
-static char * __init loglvl_str(int lvl)
+static char *loglvl_str(int lvl)
{
switch ( lvl )
{
@@ -188,6 +188,50 @@ static char * __init loglvl_str(int lvl)
return "???";
}
+static int *__read_mostly upper_thresh_adj = &xenlog_upper_thresh;
+static int *__read_mostly lower_thresh_adj = &xenlog_lower_thresh;
+static const char *__read_mostly thresh_adj = "standard";
+
+static void do_toggle_guest(unsigned char key, struct cpu_user_regs *regs)
+{
+ if ( upper_thresh_adj == &xenlog_upper_thresh )
+ {
+ upper_thresh_adj = &xenlog_guest_upper_thresh;
+ lower_thresh_adj = &xenlog_guest_lower_thresh;
+ thresh_adj = "guest";
+ }
+ else
+ {
+ upper_thresh_adj = &xenlog_upper_thresh;
+ lower_thresh_adj = &xenlog_lower_thresh;
+ thresh_adj = "standard";
+ }
+ printk("'%c' pressed -> %s log level adjustments enabled\n",
+ key, thresh_adj);
+}
+
+static void do_adj_thresh(unsigned char key)
+{
+ if ( *upper_thresh_adj < *lower_thresh_adj )
+ *upper_thresh_adj = *lower_thresh_adj;
+ printk("'%c' pressed -> %s log level: %s (rate limited %s)\n",
+ key, thresh_adj, loglvl_str(*lower_thresh_adj),
+ loglvl_str(*upper_thresh_adj));
+}
+
+static void do_inc_thresh(unsigned char key, struct cpu_user_regs *regs)
+{
+ ++*lower_thresh_adj;
+ do_adj_thresh(key);
+}
+
+static void do_dec_thresh(unsigned char key, struct cpu_user_regs *regs)
+{
+ if ( *lower_thresh_adj )
+ --*lower_thresh_adj;
+ do_adj_thresh(key);
+}
+
/*
* ********************************************************
* *************** ACCESS TO CONSOLE RING *****************
@@ -816,6 +860,12 @@ void __init console_endboot(void)
register_keyhandler('w', dump_console_ring_key,
"synchronously dump console ring buffer (dmesg)", 0);
+ register_irq_keyhandler('+', &do_inc_thresh,
+ "increase log level threshold", 0);
+ register_irq_keyhandler('-', &do_dec_thresh,
+ "decrease log level threshold", 0);
+ register_irq_keyhandler('G', &do_toggle_guest,
+ "toggle host/guest log level adjustment", 0);
/* Serial input is directed to DOM0 by default. */
switch_serial_input();
[-- Attachment #2: loglvl-adjust.patch --]
[-- Type: text/plain, Size: 3427 bytes --]
console: allow log level threshold adjustments
... from serial console so that one doesn't always need to reboot to
see more / less messages.
Note that upper thresholds are sticky, i.e. while they get adjusted
upwards when the lower threshold would otherwise end up above the upper
one, they don't get adjusted when reducing the lower one. Full
flexibility is available only via a future sysctl interface.
Note further that (meaningless) large threshold values aren't being
rejected, for the sake of not adding more checks to the code than are
really necessary for safe operation.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v4: Split out sysctl.
v3: Mention apparently missing threshold upper bound checks in
description. Make flask_sysctl() accept the new operation.
v2: Add sysctl.
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -175,7 +175,7 @@ static void __init parse_guest_loglvl(ch
_parse_loglvl(s, &xenlog_guest_lower_thresh, &xenlog_guest_upper_thresh);
}
-static char * __init loglvl_str(int lvl)
+static char *loglvl_str(int lvl)
{
switch ( lvl )
{
@@ -188,6 +188,50 @@ static char * __init loglvl_str(int lvl)
return "???";
}
+static int *__read_mostly upper_thresh_adj = &xenlog_upper_thresh;
+static int *__read_mostly lower_thresh_adj = &xenlog_lower_thresh;
+static const char *__read_mostly thresh_adj = "standard";
+
+static void do_toggle_guest(unsigned char key, struct cpu_user_regs *regs)
+{
+ if ( upper_thresh_adj == &xenlog_upper_thresh )
+ {
+ upper_thresh_adj = &xenlog_guest_upper_thresh;
+ lower_thresh_adj = &xenlog_guest_lower_thresh;
+ thresh_adj = "guest";
+ }
+ else
+ {
+ upper_thresh_adj = &xenlog_upper_thresh;
+ lower_thresh_adj = &xenlog_lower_thresh;
+ thresh_adj = "standard";
+ }
+ printk("'%c' pressed -> %s log level adjustments enabled\n",
+ key, thresh_adj);
+}
+
+static void do_adj_thresh(unsigned char key)
+{
+ if ( *upper_thresh_adj < *lower_thresh_adj )
+ *upper_thresh_adj = *lower_thresh_adj;
+ printk("'%c' pressed -> %s log level: %s (rate limited %s)\n",
+ key, thresh_adj, loglvl_str(*lower_thresh_adj),
+ loglvl_str(*upper_thresh_adj));
+}
+
+static void do_inc_thresh(unsigned char key, struct cpu_user_regs *regs)
+{
+ ++*lower_thresh_adj;
+ do_adj_thresh(key);
+}
+
+static void do_dec_thresh(unsigned char key, struct cpu_user_regs *regs)
+{
+ if ( *lower_thresh_adj )
+ --*lower_thresh_adj;
+ do_adj_thresh(key);
+}
+
/*
* ********************************************************
* *************** ACCESS TO CONSOLE RING *****************
@@ -816,6 +860,12 @@ void __init console_endboot(void)
register_keyhandler('w', dump_console_ring_key,
"synchronously dump console ring buffer (dmesg)", 0);
+ register_irq_keyhandler('+', &do_inc_thresh,
+ "increase log level threshold", 0);
+ register_irq_keyhandler('-', &do_dec_thresh,
+ "decrease log level threshold", 0);
+ register_irq_keyhandler('G', &do_toggle_guest,
+ "toggle host/guest log level adjustment", 0);
/* Serial input is directed to DOM0 by default. */
switch_serial_input();
[-- Attachment #3: Type: text/plain, Size: 127 bytes --]
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v4] console: allow log level threshold adjustments
2016-12-12 10:16 [PATCH v4] console: allow log level threshold adjustments Jan Beulich
@ 2016-12-12 10:26 ` Wei Liu
2016-12-12 10:51 ` Andrew Cooper
1 sibling, 0 replies; 3+ messages in thread
From: Wei Liu @ 2016-12-12 10:26 UTC (permalink / raw)
To: Jan Beulich
Cc: Stefano Stabellini, Wei Liu, George Dunlap, Andrew Cooper,
Ian Jackson, Tim Deegan, xen-devel
On Mon, Dec 12, 2016 at 03:16:27AM -0700, Jan Beulich wrote:
> ... from serial console so that one doesn't always need to reboot to
> see more / less messages.
>
> Note that upper thresholds are sticky, i.e. while they get adjusted
> upwards when the lower threshold would otherwise end up above the upper
> one, they don't get adjusted when reducing the lower one. Full
> flexibility is available only via a future sysctl interface.
>
> Note further that (meaningless) large threshold values aren't being
> rejected, for the sake of not adding more checks to the code than are
> really necessary for safe operation.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v4] console: allow log level threshold adjustments
2016-12-12 10:16 [PATCH v4] console: allow log level threshold adjustments Jan Beulich
2016-12-12 10:26 ` Wei Liu
@ 2016-12-12 10:51 ` Andrew Cooper
1 sibling, 0 replies; 3+ messages in thread
From: Andrew Cooper @ 2016-12-12 10:51 UTC (permalink / raw)
To: Jan Beulich, xen-devel
Cc: Stefano Stabellini, Wei Liu, George Dunlap, Tim Deegan,
Ian Jackson
On 12/12/16 10:16, Jan Beulich wrote:
> ... from serial console so that one doesn't always need to reboot to
> see more / less messages.
>
> Note that upper thresholds are sticky, i.e. while they get adjusted
> upwards when the lower threshold would otherwise end up above the upper
> one, they don't get adjusted when reducing the lower one. Full
> flexibility is available only via a future sysctl interface.
>
> Note further that (meaningless) large threshold values aren't being
> rejected, for the sake of not adding more checks to the code than are
> really necessary for safe operation.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-12-12 10:26 ` Wei Liu
2016-12-12 10:51 ` Andrew Cooper
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