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SubjectRe: [RFC] Suspicious bug in module refcounting
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On Wednesday 04 February 2009 20:41:30 Russell King wrote:
> On Wed, Feb 04, 2009 at 02:18:08PM +1030, Rusty Russell wrote:
> > gameport.c, serio.c and input.c increment their own refcount, but to get
> > into those init functions someone must be holding a refcount already (ie. a
> > module depends on this module). Ditto cyber2000fb.c, and MTD.
>
> Err, wrong. cyber2000fb.c does it in its module initialization function
> to prevent the module (when built for Shark) from being unloaded. It
> does this because it's from the days of 2.2 kernels and no one bothered
> writing the module unload support for Shark. I'm certainly not in a
> position to do that.

Thanks, here's the patch then:

Subject: cyber2000fb.c: use proper method for stopping unload if CONFIG_ARCH_SHARK

Russell explains the __module_get():
> cyber2000fb.c does it in its module initialization function
> to prevent the module (when built for Shark) from being unloaded. It
> does this because it's from the days of 2.2 kernels and no one bothered
> writing the module unload support for Shark.

Since 2.4, the correct answer has been to not define an unload fn.

Cc: Russell King <rmk+lkml@arm.linux.org.uk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/video/cyber2000fb.c b/drivers/video/cyber2000fb.c
--- a/drivers/video/cyber2000fb.c
+++ b/drivers/video/cyber2000fb.c
@@ -1736,10 +1736,8 @@ static int __init cyber2000fb_init(void)

#ifdef CONFIG_ARCH_SHARK
err = cyberpro_vl_probe();
- if (!err) {
+ if (!err)
ret = 0;
- __module_get(THIS_MODULE);
- }
#endif
#ifdef CONFIG_PCI
err = pci_register_driver(&cyberpro_driver);
@@ -1749,14 +1747,15 @@ static int __init cyber2000fb_init(void)

return ret ? err : 0;
}
+module_init(cyber2000fb_init);

+#ifndef CONFIG_ARCH_SHARK
static void __exit cyberpro_exit(void)
{
pci_unregister_driver(&cyberpro_driver);
}
-
-module_init(cyber2000fb_init);
module_exit(cyberpro_exit);
+#endif

MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("CyberPro 2000, 2010 and 5000 framebuffer driver");

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