linux/kernel/module.c, branch v2.6.18.7

load_module: no BUG if module_subsys uninitialized

2006-10-13T20:23:26Z

Invoking load_module() before param_sysfs_init() is called crashes in mod_sysfs_setup(), since the kset in module_subsys is not initialized yet. In my case, net-pf-1 is getting modprobed as a result of hotplug trying to create a UNIX socket. Calls to hotplug begin after the topology_init initcall. Another patch for the same symptom (module_subsys-initialize-earlier.patch) moves param_sysfs_init() to the subsys initcalls, but this is still not early enough in the boot process in some cases. In particular, topology_init() causes /sbin/hotplug to run, which requests net-pf-1 (the UNIX socket protocol) which can be compiled as a module. Moving param_sysfs_init() to the postcore initcalls fixes this particular race, but there might well be other cases where a usermodehelper causes a module to load earlier still. The patch makes load_module() return an error rather than crashing the kernel if invoked before module_subsys is initialized. Cc: Mark Huang Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

[PATCH] null-terminate over-long /proc/kallsyms symbols

2006-07-15T04:53:52Z

Got a customer bug report (https://bugzilla.novell.com/190296) about kernel symbols longer than 127 characters which end up in a string buffer that is not NULL terminated, leading to garbage in /proc/kallsyms. Using strlcpy prevents this from happening, even though such symbols still won't come out right. A better fix would be to not use a fixed-size buffer, but it's probably not worth the trouble. (Modversion'ed symbols even have a length limit of 60.) [bunk@stusta.de: build fix] Signed-off-by: Andreas Gruenbacher Signed-off-by: Adrian Bunk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] lockdep: core

2006-07-03T22:27:03Z

Do 'make oldconfig' and accept all the defaults for new config options - reboot into the kernel and if everything goes well it should boot up fine and you should have /proc/lockdep and /proc/lockdep_stats files. Typically if the lock validator finds some problem it will print out voluminous debug output that begins with "BUG: ..." and which syslog output can be used by kernel developers to figure out the precise locking scenario. What does the lock validator do? It "observes" and maps all locking rules as they occur dynamically (as triggered by the kernel's natural use of spinlocks, rwlocks, mutexes and rwsems). Whenever the lock validator subsystem detects a new locking scenario, it validates this new rule against the existing set of rules. If this new rule is consistent with the existing set of rules then the new rule is added transparently and the kernel continues as normal. If the new rule could create a deadlock scenario then this condition is printed out. When determining validity of locking, all possible "deadlock scenarios" are considered: assuming arbitrary number of CPUs, arbitrary irq context and task context constellations, running arbitrary combinations of all the existing locking scenarios. In a typical system this means millions of separate scenarios. This is why we call it a "locking correctness" validator - for all rules that are observed the lock validator proves it with mathematical certainty that a deadlock could not occur (assuming that the lock validator implementation itself is correct and its internal data structures are not corrupted by some other kernel subsystem). [see more details and conditionals of this statement in include/linux/lockdep.h and Documentation/lockdep-design.txt] Furthermore, this "all possible scenarios" property of the validator also enables the finding of complex, highly unlikely multi-CPU multi-context races via single single-context rules, increasing the likelyhood of finding bugs drastically. In practical terms: the lock validator already found a bug in the upstream kernel that could only occur on systems with 3 or more CPUs, and which needed 3 very unlikely code sequences to occur at once on the 3 CPUs. That bug was found and reported on a single-CPU system (!). So in essence a race will be found "piecemail-wise", triggering all the necessary components for the race, without having to reproduce the race scenario itself! In its short existence the lock validator found and reported many bugs before they actually caused a real deadlock. To further increase the efficiency of the validator, the mapping is not per "lock instance", but per "lock-class". For example, all struct inode objects in the kernel have inode->inotify_mutex. If there are 10,000 inodes cached, then there are 10,000 lock objects. But ->inotify_mutex is a single "lock type", and all locking activities that occur against ->inotify_mutex are "unified" into this single lock-class. The advantage of the lock-class approach is that all historical ->inotify_mutex uses are mapped into a single (and as narrow as possible) set of locking rules - regardless of how many different tasks or inode structures it took to build this set of rules. The set of rules persist during the lifetime of the kernel. To see the rough magnitude of checking that the lock validator does, here's a portion of /proc/lockdep_stats, fresh after bootup: lock-classes: 694 [max: 2048] direct dependencies: 1598 [max: 8192] indirect dependencies: 17896 all direct dependencies: 16206 dependency chains: 1910 [max: 8192] in-hardirq chains: 17 in-softirq chains: 105 in-process chains: 1065 stack-trace entries: 38761 [max: 131072] combined max dependencies: 2033928 hardirq-safe locks: 24 hardirq-unsafe locks: 176 softirq-safe locks: 53 softirq-unsafe locks: 137 irq-safe locks: 59 irq-unsafe locks: 176 The lock validator has observed 1598 actual single-thread locking patterns, and has validated all possible 2033928 distinct locking scenarios. More details about the design of the lock validator can be found in Documentation/lockdep-design.txt, which can also found at: http://redhat.com/~mingo/lockdep-patches/lockdep-design.txt [bunk@stusta.de: cleanups] Signed-off-by: Ingo Molnar Signed-off-by: Arjan van de Ven Signed-off-by: Adrian Bunk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] lockdep: add is_module_address()

2006-07-03T22:27:00Z

Add is_module_address() method - to be used by lockdep. Signed-off-by: Ingo Molnar Signed-off-by: Arjan van de Ven Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Remove obsolete #include

2006-06-30T17:25:36Z

Signed-off-by: Jörn Engel Signed-off-by: Adrian Bunk

[PATCH] load_module() cleanup

2006-06-28T21:59:04Z

Undo bizarre declaration in load_module(). Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] Add EXPORT_UNUSED_SYMBOL and EXPORT_UNUSED_SYMBOL_GPL

2006-06-28T21:59:04Z

Temporarily add EXPORT_UNUSED_SYMBOL and EXPORT_UNUSED_SYMBOL_GPL. These will be used as a transition measure for symbols that aren't used in the kernel and are on the way out. When a module uses such a symbol, a warning is printk'd at modprobe time. The main reason for removing unused exports is size: eacho export takes roughly between 100 and 150 bytes of kernel space in the binary. This patch gives users the option to immediately get this size gain via a config option. Signed-off-by: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild

2006-06-26T18:05:15Z

* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild: (40 commits) kbuild: trivial fixes in Makefile kbuild: adding symbols in Kconfig and defconfig to TAGS kbuild: replace abort() with exit(1) kbuild: support for %.symtypes files kbuild: fix silentoldconfig recursion kbuild: add option for stripping modules while installing them kbuild: kill some false positives from modpost kbuild: export-symbol usage report generator kbuild: fix make -rR breakage kbuild: append -dirty for updated but uncommited changes kbuild: append git revision for all untagged commits kbuild: fix module.symvers parsing in modpost kbuild: ignore make's built-in rules & variables kbuild: bugfix with initramfs kbuild: modpost build fix kbuild: check license compatibility when building modules kbuild: export-type enhancement to modpost.c kbuild: add dependency on kernel.release to the package targets kbuild: `make kernelrelease' speedup kconfig: KCONFIG_OVERWRITECONFIG ...

[PATCH] x86_64: reliable stack trace support

2006-06-26T17:48:17Z

These are the generic bits needed to enable reliable stack traces based on Dwarf2-like (.eh_frame) unwind information. Subsequent patches will enable x86-64 and i386 to make use of this. Thanks to Andi Kleen and Ingo Molnar, who pointed out several possibilities for improvement. Signed-off-by: Jan Beulich Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds

[PATCH] ensure NULL deref can't possibly happen in is_exported()

2006-06-25T17:00:59Z

If CONFIG_KALLSYMS is defined and if it should happen that is_exported() is given a NULL 'mod' and lookup_symbol(name, __start___ksymtab, __stop___ksymtab) returns 0, then we'll end up dereferencing a NULL pointer. Signed-off-by: Jesper Juhl Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds