diff mbox

[v4,1/3] powerpc/xmon: Fix an unexpected xmon on/off state change

Message ID 20170322192751.30531-2-gpiccoli@linux.vnet.ibm.com (mailing list archive)
State Accepted
Headers show

Commit Message

Guilherme G. Piccoli March 22, 2017, 7:27 p.m. UTC 
From: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>

Once xmon is triggered by sysrq-x, it is enabled always afterwards even
if it is disabled during boot. This will cause a system reset interrupt
fail to dump. So keep xmon in its original state after exit.

We have several ways to set xmon on or off.
1) by a build config CONFIG_XMON_DEFAULT.
2) by a boot cmdline with xmon or xmon=early or xmon=on to enable xmon
and xmon=off to disable xmon. This value will override that in step 1.
3) by a debugfs interface, as proposed in this patchset.
And this value can override those in step 1 and 2.

Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
---
v3: changed xmon_off to xmon_on, simplifying the logic [mpe suggestion].

 arch/powerpc/xmon/xmon.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

Comments

Michael Ellerman March 31, 2017, 12:33 p.m. UTC | #1 
On Wed, 2017-03-22 at 19:27:49 UTC, "Guilherme G. Piccoli" wrote:
> From: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
> 
> Once xmon is triggered by sysrq-x, it is enabled always afterwards even
> if it is disabled during boot. This will cause a system reset interrupt
> fail to dump. So keep xmon in its original state after exit.
> 
> We have several ways to set xmon on or off.
> 1) by a build config CONFIG_XMON_DEFAULT.
> 2) by a boot cmdline with xmon or xmon=early or xmon=on to enable xmon
> and xmon=off to disable xmon. This value will override that in step 1.
> 3) by a debugfs interface, as proposed in this patchset.
> And this value can override those in step 1 and 2.
> 
> Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/3b5bf42b81d56085fd58692b5117f6

cheers
diff mbox

Patch

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 16321ad9e70c..a89db1b3f66d 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -76,6 +76,7 @@  static int xmon_gate;
 #endif /* CONFIG_SMP */
 
 static unsigned long in_xmon __read_mostly = 0;
+static int xmon_on = IS_ENABLED(CONFIG_XMON_DEFAULT);
 
 static unsigned long adrs;
 static int size = 1;
@@ -3302,6 +3303,8 @@  static void sysrq_handle_xmon(int key)
 	/* ensure xmon is enabled */
 	xmon_init(1);
 	debugger(get_irq_regs());
+	if (!xmon_on)
+		xmon_init(0);
 }
 
 static struct sysrq_key_op sysrq_xmon_op = {
@@ -3318,7 +3321,7 @@  static int __init setup_xmon_sysrq(void)
 __initcall(setup_xmon_sysrq);
 #endif /* CONFIG_MAGIC_SYSRQ */
 
-static int __initdata xmon_early, xmon_off;
+static int __initdata xmon_early;
 
 static int __init early_parse_xmon(char *p)
 {
@@ -3326,10 +3329,12 @@  static int __init early_parse_xmon(char *p)
 		/* just "xmon" is equivalent to "xmon=early" */
 		xmon_init(1);
 		xmon_early = 1;
-	} else if (strncmp(p, "on", 2) == 0)
+		xmon_on = 1;
+	} else if (strncmp(p, "on", 2) == 0) {
 		xmon_init(1);
-	else if (strncmp(p, "off", 3) == 0)
-		xmon_off = 1;
+		xmon_on = 1;
+	} else if (strncmp(p, "off", 3) == 0)
+		xmon_on = 0;
 	else if (strncmp(p, "nobt", 4) == 0)
 		xmon_no_auto_backtrace = 1;
 	else
@@ -3341,10 +3346,8 @@  early_param("xmon", early_parse_xmon);
 
 void __init xmon_setup(void)
 {
-#ifdef CONFIG_XMON_DEFAULT
-	if (!xmon_off)
+	if (xmon_on)
 		xmon_init(1);
-#endif
 	if (xmon_early)
 		debugger(NULL);
 }