Bug 55595
| Summary: | 2.4.9-7 breaks kernel module interfaces for kiovec | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | Douglas Miller <drmiller> |
| Component: | kernel | Assignee: | Arjan van de Ven <arjanv> |
| Status: | CLOSED NOTABUG | QA Contact: | Brock Organ <borgan> |
| Severity: | high | Docs Contact: | |
| Priority: | medium | ||
| Version: | 7.2 | CC: | drmiller |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2001-11-02 18:31:17 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
No binary compatibility for kernel modules is guaranteed to work between different kernels. In fact, I can guarantee you that you MUST recompile kernel modules for different kernel versions..... Ummm... 2 points. This isn't a binary-only module issue - this is a source level incompatibility. You just deleted two public interfaces in an allegedly stable release (2.4.X), even though they weren't broken per se. This is generally considered "a bad thing"(TM). Second, why were modversions added to the kernel and why do Red Hat ship with modversions enabled if you're supposed to rebuild modules for every different kernel ? It seems that they serve no useful purpose in that case. Tim Re modversions: the primary reason for those is to prevent accentally loading modules for the wrong kernel (say i386 modules into a i686 kernel). Internal kernel interfaces have never been stable and probably never will be. This was an upstream change and we try to mirror the upstream kernels. The exported, stable, interfaces of the kernel (syscalls, ioctls and several /proc files) are of course intended to be VERY non changing, and compatibility is hardly ever broken. |
From Bugzilla Helper: User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.4.2-2 i686) Description of problem: The 2.4.9-7 kernel shipped with 7.2 breaks the interfaces for alloc_kiovec/free_kiovec, specifcally by removing the interfaces. Granted, they are replaced by more performant interfaces but this still breaks any kernel modules that are not compiled, and breaks module compatability between the 2.4.7-10 kernel also shipped with 7.2. A better approach would be to provide both interfaces. Attached (addtnl info) is a patch that does just that. Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1. try to load a kernel module that uses all_kiovec on 2.4.9-7 kernel 2. 3. Additional info: diff -Nru linux-RH/fs/iobuf.c linux/fs/iobuf.c --- linux-RH/fs/iobuf.c Fri Nov 2 08:25:27 2001 +++ linux/fs/iobuf.c Fri Nov 2 08:44:24 2001 @@ -164,3 +164,41 @@ } +int alloc_kiovec(int nr, struct kiobuf **bufp) +{ + int i; + struct kiobuf *iobuf; + + for (i = 0; i < nr; i++) { + iobuf = kmem_cache_alloc(kiobuf_cachep, SLAB_KERNEL); + if (!iobuf) { + free_kiovec(i, bufp); + return -ENOMEM; + } + kiobuf_init(iobuf); + if (alloc_kiobuf_bhs_sz(iobuf, KIO_MAX_SECTORS)) { + kmem_cache_free(kiobuf_cachep, iobuf); + free_kiovec(i, bufp); + return -ENOMEM; + } + bufp[i] = iobuf; + } + + return 0; +} + +void free_kiovec(int nr, struct kiobuf **bufp) +{ + int i; + struct kiobuf *iobuf; + + for (i = 0; i < nr; i++) { + iobuf = bufp[i]; + if (iobuf->locked) + unlock_kiovec(1, &iobuf); + if (iobuf->array_len > KIO_STATIC_PAGES) + kfree (iobuf->maplist); + free_kiobuf_bhs_sz(iobuf, KIO_MAX_SECTORS); + kmem_cache_free(kiobuf_cachep, bufp[i]); + } +} diff -Nru linux-RH/include/linux/iobuf.h linux/include/linux/iobuf.h --- linux-RH/include/linux/iobuf.h Fri Nov 2 08:25:27 2001 +++ linux/include/linux/iobuf.h Fri Nov 2 08:46:08 2001 @@ -73,6 +73,8 @@ void simple_wakeup_kiobuf(struct kiobuf *); int alloc_kiovec_sz(int nr, struct kiobuf **, int *); void free_kiovec_sz(int nr, struct kiobuf **, int *); +int alloc_kiovec(int nr, struct kiobuf **); +void free_kiovec(int nr, struct kiobuf **); int expand_kiobuf(struct kiobuf *, int); void kiobuf_wait_for_io(struct kiobuf *); extern int alloc_kiobuf_bhs(struct kiobuf *); diff -Nru linux-RH/kernel/ksyms.c linux/kernel/ksyms.c --- linux-RH/kernel/ksyms.c Fri Nov 2 08:25:27 2001 +++ linux/kernel/ksyms.c Fri Nov 2 08:46:31 2001 @@ -421,6 +421,8 @@ /* Kiobufs */ EXPORT_SYMBOL(alloc_kiovec_sz); EXPORT_SYMBOL(free_kiovec_sz); +EXPORT_SYMBOL(alloc_kiovec); +EXPORT_SYMBOL(free_kiovec); EXPORT_SYMBOL(expand_kiobuf); EXPORT_SYMBOL(map_user_kiobuf);