xenbus: advertize control feature flags

PATCH Superseded Paul Durrant 2 participants 5 messages Oct 10, 2016 Xen hypervisor interface

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Paul Durrant

author

2016-10-10 08:03 UTC #0 lore raw

PATCH 1/1 xenbus: advertize control feature flags

The Xen docs specify several flags which a guest can set to advertize which values of the xenstore control/shutdown key it will recognize. This patch adds code to write all the relevant feature-flag keys.

Signed-off-by Paul Durrant <[email protected]>

Cc Boris Ostrovsky <[email protected]>

Cc David Vrabel <[email protected]>

Cc Juergen Gross <[email protected]>

---
 drivers/xen/manage.c | 45 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 10 deletions(-)

drivers/xen/manage.c +35 ~~-10~~

index e12bd36..86cf57c 100644
@@ -170,6 +170,7 @@ out:
 struct shutdown_handler {
 	const char *command;
 	void (*cb)(void);
+	bool flag;
 };
 
 static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)

@@ -206,21 +207,22 @@ static void do_reboot(void)
 	ctrl_alt_del();
 }
 
+static struct shutdown_handler shutdown_handlers[] = {
+	{ "poweroff", do_poweroff, true },
+	{ "halt", do_poweroff, true },
+	{ "reboot", do_reboot, false },
+#ifdef CONFIG_HIBERNATE_CALLBACKS
+	{ "suspend", do_suspend, true },
+#endif
+	{NULL, NULL, false },
+};
+
 static void shutdown_handler(struct xenbus_watch *watch,
 			     const char **vec, unsigned int len)
 {
 	char *str;
 	struct xenbus_transaction xbt;
 	int err;
-	static struct shutdown_handler handlers[] = {
-		{ "poweroff",	do_poweroff },
-		{ "halt",	do_poweroff },
-		{ "reboot",	do_reboot   },
-#ifdef CONFIG_HIBERNATE_CALLBACKS
-		{ "suspend",	do_suspend  },
-#endif
-		{NULL, NULL},
-	};
 	static struct shutdown_handler *handler;
 
 	if (shutting_down != SHUTDOWN_INVALID)

@@ -238,7 +240,7 @@ static void shutdown_handler(struct xenbus_watch *watch,
 		return;
 	}
 
-	for (handler = &handlers[0]; handler->command; handler++) {
+	for (handler = &shutdown_handlers[0]; handler->command; handler++) {
 		if (strcmp(str, handler->command) == 0)
 			break;
 	}

@@ -309,8 +311,31 @@ static struct notifier_block xen_reboot_nb = {
 
 static int setup_shutdown_watcher(void)
 {
+	static struct shutdown_handler *handler;
 	int err;
 
+	for (handler = &shutdown_handlers[0]; handler->command; handler++) {
+		const char *fmt = "feature-%s";
+		int size;
+		char *node;
+
+		if (!handler->flag)
+			continue;
+
+		size = snprintf(NULL, 0, fmt, handler->command);
+
+		node = kmalloc(++size, GFP_KERNEL);
+		if (!node) {
+			pr_err("Failed to allocate feature flag\n");
+			return -ENOMEM;
+		}
+
+		(void) snprintf(node, size, fmt, handler->command);
+		xenbus_printf(XBT_NIL, "control", node, "%u", 1);
+
+		kfree(node);
+	}
+
 	err = register_xenbus_watch(&shutdown_watch);
 	if (err) {
 		pr_err("Failed to set shutdown watcher\n");

Signature · 7 lines

2.1.4


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Juergen Gross

maintainer

2016-10-10 09:11 UTC #1 lore raw

Quoted 25 lines · Paul Durrant

The Xen docs specify several flags which a guest can set to advertize which values of the xenstore control/shutdown key it will recognize. This patch adds code to write all the relevant feature-flag keys.
Signed-off-by Paul Durrant <[email protected]>
Cc Boris Ostrovsky <[email protected]>
Cc David Vrabel <[email protected]>
Cc Juergen Gross <[email protected]>
---
 drivers/xen/manage.c | 45 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 10 deletions(-)
drivers/xen/manage.c +1 -0
index e12bd36..86cf57c 100644
@@ -170,6 +170,7 @@ out:
 struct shutdown_handler {
 	const char *command;
 	void (*cb)(void);
+	bool flag;
 };
 
 static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)

drivers/xen/manage.c static void do_reboot(void) · line 213

Quoted 7 lines

drivers/xen/manage.c +4 -0

@@ -206,21 +207,22 @@ static void do_reboot(void)
 	ctrl_alt_del();
 }
 
+static struct shutdown_handler shutdown_handlers[] = {
+	{ "poweroff", do_poweroff, true },
+	{ "halt", do_poweroff, true },
+	{ "reboot", do_reboot, false },

I think you meant to set the flag to "false" for halt and "true" for reboot, no?

Juergen

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Paul Durrant

author

2016-10-10 09:28 UTC #2 lore raw

Quoted 40 lines

-----Original Message-----
From: Juergen Gross [mailto:[email protected]]
Sent: 10 October 2016 10:11
To: Paul Durrant <[email protected]>; [email protected]; [email protected]
Cc: Boris Ostrovsky <[email protected]>; David Vrabel <[email protected]>
Subject: Re: [PATCH] xenbus: advertize control feature flags
Quoted 10 lines · Paul Durrant
The Xen docs specify several flags which a guest can set to advertize which values of the xenstore control/shutdown key it will recognize. This patch adds code to write all the relevant feature-flag keys.
Signed-off-by Paul Durrant <[email protected]>
Cc Boris Ostrovsky <[email protected]>
Cc David Vrabel <[email protected]>
Cc Juergen Gross <[email protected]>
---
 drivers/xen/manage.c | 45 +++++++++++++++++++++++++++++++++++--
--------
Quoted 7 lines
 1 file changed, 35 insertions(+), 10 deletions(-)
drivers/xen/manage.c +0 -0
index e12bd36..86cf57c 100644
drivers/xen/manage.c out: · line 176
Quoted 7 lines
drivers/xen/manage.c +1 -0
@@ -170,6 +170,7 @@ out:
 struct shutdown_handler {
 	const char *command;
 	void (*cb)(void);
+	bool flag;
 };
 
 static int poweroff_nb(struct notifier_block *cb, unsigned long code, void
*unused)
Quoted 4 lines
drivers/xen/manage.c +0 -0
@@ -206,21 +207,22 @@ static void do_reboot(void)
 	ctrl_alt_del();
 }
 

Quoted 8 lines

drivers/xen/manage.c static void do_reboot(void) · line 213
Quoted 4 lines
drivers/xen/manage.c +4 -0
+static struct shutdown_handler shutdown_handlers[] = {
+	{ "poweroff", do_poweroff, true },
+	{ "halt", do_poweroff, true },
+	{ "reboot", do_reboot, false },
I think you meant to set the flag to "false" for halt and "true" for reboot, no?

Yes, you're right. Don't know why I got that backwards. Will fix in v2.

Paul

Quoted 2 lines

Juergen

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Juergen Gross

maintainer

2016-10-10 09:17 UTC #3 lore raw

In reply to Paul Durrant

Quoted 31 lines · Paul Durrant

The Xen docs specify several flags which a guest can set to advertize which values of the xenstore control/shutdown key it will recognize. This patch adds code to write all the relevant feature-flag keys.
Signed-off-by Paul Durrant <[email protected]>
Cc Boris Ostrovsky <[email protected]>
Cc David Vrabel <[email protected]>
Cc Juergen Gross <[email protected]>
---
 drivers/xen/manage.c | 45 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 10 deletions(-)
drivers/xen/manage.c +8 -0
index e12bd36..86cf57c 100644
@@ -309,8 +311,31 @@ static struct notifier_block xen_reboot_nb = {
 
 static int setup_shutdown_watcher(void)
 {
+	static struct shutdown_handler *handler;
 	int err;
 
+	for (handler = &shutdown_handlers[0]; handler->command; handler++) {
+		const char *fmt = "feature-%s";
+		int size;
+		char *node;
+
+		if (!handler->flag)
+			continue;

drivers/xen/manage.c static struct notifier_block xen_reboot_nb = { · line 333

Quoted 10 lines

drivers/xen/manage.c +10 -0

+
+		size = snprintf(NULL, 0, fmt, handler->command);
+
+		node = kmalloc(++size, GFP_KERNEL);
+		if (!node) {
+			pr_err("Failed to allocate feature flag\n");
+			return -ENOMEM;
+		}
+
+		(void) snprintf(node, size, fmt, handler->command);

One other nit: please us kasprintf() instead of open coding it.

Juergen

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Paul Durrant

author

2016-10-10 09:31 UTC #4 lore raw

Quoted 47 lines

-----Original Message-----
From: Juergen Gross [mailto:[email protected]]
Sent: 10 October 2016 10:17
To: Paul Durrant <[email protected]>; [email protected]; [email protected]
Cc: Boris Ostrovsky <[email protected]>; David Vrabel <[email protected]>
Subject: Re: [PATCH] xenbus: advertize control feature flags
Quoted 10 lines · Paul Durrant
The Xen docs specify several flags which a guest can set to advertize which values of the xenstore control/shutdown key it will recognize. This patch adds code to write all the relevant feature-flag keys.
Signed-off-by Paul Durrant <[email protected]>
Cc Boris Ostrovsky <[email protected]>
Cc David Vrabel <[email protected]>
Cc Juergen Gross <[email protected]>
---
 drivers/xen/manage.c | 45 +++++++++++++++++++++++++++++++++++--
--------
Quoted 8 lines
 1 file changed, 35 insertions(+), 10 deletions(-)
drivers/xen/manage.c +0 -0
index e12bd36..86cf57c 100644
drivers/xen/manage.c static struct notifier_block xen_reboot_nb = { · line 317
Quoted 7 lines
drivers/xen/manage.c +2 -0
@@ -309,8 +311,31 @@ static struct notifier_block xen_reboot_nb = {
 
 static int setup_shutdown_watcher(void)
 {
+	static struct shutdown_handler *handler;
 	int err;
 
+	for (handler = &shutdown_handlers[0]; handler->command;
handler++) {
Quoted 10 lines
drivers/xen/manage.c +10 -0
+		const char *fmt = "feature-%s";
+		int size;
+		char *node;
+
+		if (!handler->flag)
+			continue;
+
+		size = snprintf(NULL, 0, fmt, handler->command);
+
+		node = kmalloc(++size, GFP_KERNEL);

Quoted 9 lines

drivers/xen/manage.c static struct notifier_block xen_reboot_nb = { · line 333
Quoted 6 lines
drivers/xen/manage.c +6 -0
+		if (!node) {
+			pr_err("Failed to allocate feature flag\n");
+			return -ENOMEM;
+		}
+
+		(void) snprintf(node, size, fmt, handler->command);
One other nit: please us kasprintf() instead of open coding it.

Yes, that would be better.

Cheers,

Paul

Quoted 2 lines

Juergen

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