0005634: rmmod hangs when trying to remove a busy kernel module using delete_module() from µClibc

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Category

Severity

Reproducibility

Date Submitted

Last Update

0005634

[BusyBox] Kernel Module Support

minor

always

10-22-08 00:46

10-22-08 04:59

Reporter

zaphod

View Status

public

Assigned To

uClibc

Priority

normal

Resolution

open

Status

assigned

Product Version

svn

Summary

0005634: rmmod hangs when trying to remove a busy kernel module using delete_module() from µClibc

Description

Busybox uses delete_module() to remove a kernel module. It assumes delete_module() to be a function with the following prototype:

int delete_module(const char *module, unsigned int flags);

Unfortunatly µClibc provides delete_module() as follows:

int delete_module(const char *name);

The flags containing O_NONBLOCK gets lost on the way to the kernel and rmmod hangs.

To fix this simply fall back to busybox own implementation, which is used in all cases except for µClibc:

#ifdef __UCLIBC__
extern int delete_module(const char *module, unsigned int flags);
#else
# include <sys/syscall.h>
# define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)
#endif

Additional Information

in all linux-2.4.x delete_module was a syscall1 (as opposed to later kernels). I'll take a look.

Attached Files

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Notes
(0013974) zaphod 10-22-08 04:35	In a note in the µClibc delete_module report you asked, whether I could check the syscall2 version of delete_module under a 2.4 kernel. The following is from strace rmmod under 2.4.32: delete_module("ip_conntrack_ftp", O_RDONLY\|O_EXCL\|O_NONBLOCK) = -1 EBUSY (Device or resource busy) rmmod sets the flags to O_NONBLOCK\|O_EXCL, O_RDONLY is defined as 0, so delete_module passes the right flags to the kernel and the kernel ignores them as expected.

(0013984) bernhardf 10-22-08 04:59	thanks. If relly needed that #ifndef could be extended to #if defined __UCLIBC__ && (__UCLIBC_MAJOR__ == 0 && __UCLIBC_MINOR__ == 9 && __UCLIBC_SUBLEVEL__ < 30)

Issue History
Date Modified	Username	Field	Change
10-22-08 00:46	zaphod	New Issue
10-22-08 00:46	zaphod	Status	new => assigned
10-22-08 00:46	zaphod	Assigned To	=> BusyBox
10-22-08 01:13	bernhardf	Assigned To	BusyBox => uClibc
10-22-08 01:13	bernhardf	Additional Information Updated
10-22-08 04:35	zaphod	Note Added: 0013974
10-22-08 04:59	bernhardf	Note Added: 0013984