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Subject[PATCH] staging/panel: prevent driver from calling misc_deregister twice on same ressource
Date
From: Peter Huewe <peterhuewe@gmx.de>

This patch prevents the driver from calling misc_deregister twice on the same
ressouce when unloading the driver.
Unloading the driver without this patch results in a Kernel BUG like this:
Panel driver version 0.9.5 registered on parport0 (io=0x378).
BUG: unable to handle kernel paging request at 0000000000100108
IP: [<ffffffff803c02ee>] misc_deregister+0x2d/0x90
PGD 6caff067 PUD 762b7067 PMD 0
Oops: 0002 [#1] PREEMPT SMP
last sysfs file: /sys/devices/platform/w83627hf.656/in8_input
...

This patch fixes this issue, although maybe not in the best way possible :)

linux version v2.6.32-rc1 - linus git tree, Di 29. Sep 01:10:18 CEST 2009

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
---
diff --git a/drivers/staging/panel/panel.c b/drivers/staging/panel/panel.c
old mode 100644
new mode 100755
index dd7d3fd..4ce399b
--- a/drivers/staging/panel/panel.c
+++ b/drivers/staging/panel/panel.c
@@ -2071,11 +2071,15 @@ static void panel_detach(struct parport *port)
return;
}

- if (keypad_enabled && keypad_initialized)
+ if (keypad_enabled && keypad_initialized) {
misc_deregister(&keypad_dev);
+ keypad_initialized = 0;
+ }

- if (lcd_enabled && lcd_initialized)
+ if (lcd_enabled && lcd_initialized) {
misc_deregister(&lcd_dev);
+ lcd_initialized = 0;
+ }

parport_release(pprt);
parport_unregister_device(pprt);
@@ -2211,13 +2215,16 @@ static void __exit panel_cleanup_module(void)
del_timer(&scan_timer);

if (pprt != NULL) {
- if (keypad_enabled)
+ if (keypad_enabled) {
misc_deregister(&keypad_dev);
+ keypad_initialized = 0;
+ }

if (lcd_enabled) {
panel_lcd_print("\x0cLCD driver " PANEL_VERSION
"\nunloaded.\x1b[Lc\x1b[Lb\x1b[L-");
misc_deregister(&lcd_dev);
+ lcd_initialized = 0;
}

/* TODO: free all input signals */

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