Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | [PATCH 2/2] modules: Whine about suspicious return values from module's ->init() hook | Date | Tue, 4 Mar 2008 23:22:26 +1100 |
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Subject: Whine about suspicious return values from module's ->init() hook Date: Mon, 11 Feb 2008 01:09:06 +0300 From: Alexey Dobriyan <adobriyan@gmail.com>
Return value convention of module's init functions is 0/-E. Sometimes, e.g. during forward-porting mistakes happen and buggy module created, where result of comparison "workqueue != NULL" is propagated all the way up to sys_init_module. What happens is that some other module created workqueue in question, our module created it again and module was successfully loaded.
Or it could be some other bug.
Let's make such mistakes much more visible. In retrospective, such messages would noticeably shorten some of my head-scratching sessions.
Note, that dump_stack() is just a way to get attention from user. Sample message:
sys_init_module: 'foo'->init suspiciously returned 1, it should follow 0/-E convention sys_init_module: loading module anyway... Pid: 4223, comm: modprobe Not tainted 2.6.24-25f666300625d894ebe04bac2b4b3aadb907c861 #5
Call Trace: [<ffffffff80254b05>] sys_init_module+0xe5/0x1d0 [<ffffffff8020b39b>] system_call_after_swapgs+0x7b/0x80
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> --- kernel/module.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff -u --- a/kernel/module.c +++ b/kernel/module.c @@ -2174,6 +2174,14 @@ sys_init_module(void __user *umod, wake_up(&module_wq); return ret; } + if (ret > 0) { + printk(KERN_WARNING "%s: '%s'->init suspiciously returned %d, " + "it should follow 0/-E convention\n" + KERN_WARNING "%s: loading module anyway...\n", + __func__, mod->name, ret, + __func__); + dump_stack(); + } /* Now it's a first class citizen! */ mutex_lock(&module_mutex);
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