Re: linux-2.6.17-mm6: can not boot: bad spinlock magic

[Andrew Morton]

On Thu, 6 Jul 2006 13:08:49 +0400
Paul Drynoff <pauldrynoff@xxxxxxxxx> wrote:

> I tried 2.6.17-mm6, and got durring boot:
> fb0: VGA16 VGA frame buffer device
> BUG: spinlock bad magic on CPU#0, swapper/1
> _raw_spin_lock
> _spin_lock_irqsave
> __down
> __down_faied
> .text.lock.cm_sbs
> acpi_ac_init
> init
> kernel_thread_helper

Thanks.  This'll probably help.


From: Andrew Morton <akpm@xxxxxxxx>

cm_sbs_sem is being downed (via acpi_ac_init->acpi_lock_ac_dir) before it is
initialised, with grave results.

- Make it a mutex

- Initialise it

- Make it static

- Clean other stuff up.

Cc: "Brown, Len" <len.brown@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---

 drivers/acpi/cm_sbs.c |   46 ++++++++++++----------------------------
 1 file changed, 14 insertions(+), 32 deletions(-)

diff -puN drivers/acpi/cm_sbs.c~acpi-initialise-cm_sbs_sem drivers/acpi/cm_sbs.c
--- a/drivers/acpi/cm_sbs.c~acpi-initialise-cm_sbs_sem
+++ a/drivers/acpi/cm_sbs.c
@@ -39,50 +39,43 @@ ACPI_MODULE_NAME("cm_sbs")
 static struct proc_dir_entry *acpi_ac_dir;
 static struct proc_dir_entry *acpi_battery_dir;
 
-static struct semaphore cm_sbs_sem;
+static DEFINE_MUTEX(cm_sbs_mutex);
 
-static int lock_ac_dir_cnt = 0;
-static int lock_battery_dir_cnt = 0;
+static int lock_ac_dir_cnt;
+static int lock_battery_dir_cnt;
 
 struct proc_dir_entry *acpi_lock_ac_dir(void)
 {
-
-	down(&cm_sbs_sem);
-	if (!acpi_ac_dir) {
+	mutex_lock(&cm_sbs_mutex);
+	if (!acpi_ac_dir)
 		acpi_ac_dir = proc_mkdir(ACPI_AC_CLASS, acpi_root_dir);
-	}
 	if (acpi_ac_dir) {
 		lock_ac_dir_cnt++;
 	} else {
 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 				  "Cannot create %s\n", ACPI_AC_CLASS));
 	}
-	up(&cm_sbs_sem);
+	mutex_unlock(&cm_sbs_mutex);
 	return acpi_ac_dir;
 }
-
 EXPORT_SYMBOL(acpi_lock_ac_dir);
 
 void acpi_unlock_ac_dir(struct proc_dir_entry *acpi_ac_dir_param)
 {
-
-	down(&cm_sbs_sem);
-	if (acpi_ac_dir_param) {
+	mutex_lock(&cm_sbs_mutex);
+	if (acpi_ac_dir_param)
 		lock_ac_dir_cnt--;
-	}
 	if (lock_ac_dir_cnt == 0 && acpi_ac_dir_param && acpi_ac_dir) {
 		remove_proc_entry(ACPI_AC_CLASS, acpi_root_dir);
 		acpi_ac_dir = 0;
 	}
-	up(&cm_sbs_sem);
+	mutex_unlock(&cm_sbs_mutex);
 }
-
 EXPORT_SYMBOL(acpi_unlock_ac_dir);
 
 struct proc_dir_entry *acpi_lock_battery_dir(void)
 {
-
-	down(&cm_sbs_sem);
+	mutex_lock(&cm_sbs_mutex);
 	if (!acpi_battery_dir) {
 		acpi_battery_dir =
 		    proc_mkdir(ACPI_BATTERY_CLASS, acpi_root_dir);
@@ -93,39 +86,28 @@ struct proc_dir_entry *acpi_lock_battery
 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 				  "Cannot create %s\n", ACPI_BATTERY_CLASS));
 	}
-	up(&cm_sbs_sem);
+	mutex_unlock(&cm_sbs_mutex);
 	return acpi_battery_dir;
 }
-
 EXPORT_SYMBOL(acpi_lock_battery_dir);
 
 void acpi_unlock_battery_dir(struct proc_dir_entry *acpi_battery_dir_param)
 {
-
-	down(&cm_sbs_sem);
-	if (acpi_battery_dir_param) {
+	mutex_lock(&cm_sbs_mutex);
+	if (acpi_battery_dir_param)
 		lock_battery_dir_cnt--;
-	}
 	if (lock_battery_dir_cnt == 0 && acpi_battery_dir_param
 	    && acpi_battery_dir) {
 		remove_proc_entry(ACPI_BATTERY_CLASS, acpi_root_dir);
 		acpi_battery_dir = 0;
 	}
-	up(&cm_sbs_sem);
+	mutex_unlock(&cm_sbs_mutex);
 	return;
 }
-
 EXPORT_SYMBOL(acpi_unlock_battery_dir);
 
 static int __init acpi_cm_sbs_init(void)
 {
-
-	if (acpi_disabled)
-		return 0;
-
-	init_MUTEX(&cm_sbs_sem);
-
 	return 0;
 }
-
 subsys_initcall(acpi_cm_sbs_init);
_

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