linux/kernel/module.c, branch v3.19

module: make module_refcount() a signed integer.

2015-01-22T00:45:54Z

James Bottomley points out that it will be -1 during unload. It's only used for diagnostics, so let's not hide that as it could be a clue as to what's gone wrong. Cc: Jason Wessel Acked-and-documention-added-by: James Bottomley Reviewed-by: Masami Hiramatsu Signed-off-by: Rusty Russell

module: fix race in kallsyms resolution during module load success.

2015-01-20T01:08:34Z

The kallsyms routines (module_symbol_name, lookup_module_* etc) disable preemption to walk the modules rather than taking the module_mutex: this is because they are used for symbol resolution during oopses. This works because there are synchronize_sched() and synchronize_rcu() in the unload and failure paths. However, there's one case which doesn't have that: the normal case where module loading succeeds, and we free the init section. We don't want a synchronize_rcu() there, because it would slow down module loading: this bug was introduced in 2009 to speed module loading in the first place. Thus, we want to do the free in an RCU callback. We do this in the simplest possible way by allocating a new rcu_head: if we put it in the module structure we'd have to worry about that getting freed. Reported-by: Rui Xiang Signed-off-by: Rusty Russell

module: remove mod arg from module_free, rename module_memfree().

2015-01-20T01:08:33Z

Nothing needs the module pointer any more, and the next patch will call it from RCU, where the module itself might no longer exist. Removing the arg is the safest approach. This just codifies the use of the module_alloc/module_free pattern which ftrace and bpf use. Signed-off-by: Rusty Russell Acked-by: Alexei Starovoitov Cc: Mikael Starvik Cc: Jesper Nilsson Cc: Ralf Baechle Cc: Ley Foon Tan Cc: Benjamin Herrenschmidt Cc: Chris Metcalf Cc: Steven Rostedt Cc: x86@kernel.org Cc: Ananth N Mavinakayanahalli Cc: Anil S Keshavamurthy Cc: Masami Hiramatsu Cc: linux-cris-kernel@axis.com Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: nios2-dev@lists.rocketboards.org Cc: linuxppc-dev@lists.ozlabs.org Cc: sparclinux@vger.kernel.org Cc: netdev@vger.kernel.org

module_arch_freeing_init(): new hook for archs before module->module_init freed.

2015-01-20T01:08:32Z

Archs have been abusing module_free() to clean up their arch-specific allocations. Since module_free() is also (ab)used by BPF and trace code, let's keep it to simple allocations, and provide a hook called before that. This means that avr32, ia64, parisc and s390 no longer need to implement their own module_free() at all. avr32 doesn't need module_finalize() either. Signed-off-by: Rusty Russell Cc: Chris Metcalf Cc: Haavard Skinnemoen Cc: Hans-Christian Egtvedt Cc: Tony Luck Cc: Fenghua Yu Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: linux-kernel@vger.kernel.org Cc: linux-ia64@vger.kernel.org Cc: linux-parisc@vger.kernel.org Cc: linux-s390@vger.kernel.org

Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2014-12-19T04:55:41Z

Pull module updates from Rusty Russell: "The exciting thing here is the getting rid of stop_machine on module removal. This is possible by using a simple atomic_t for the counter, rather than our fancy per-cpu counter: it turns out that no one is doing a module increment per net packet, so the slowdown should be in the noise" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: param: do not set store func without write perm params: cleanup sysfs allocation kernel:module Fix coding style errors and warnings. module: Remove stop_machine from module unloading module: Replace module_ref with atomic_t refcnt lib/bug: Use RCU list ops for module_bug_list module: Unlink module with RCU synchronizing instead of stop_machine module: Wait for RCU synchronizing before releasing a module

kernel:module Fix coding style errors and warnings.

2014-11-11T06:37:47Z

Fixed codin style errors and warnings. Changes printk with print_debug/warn. Changed seq_printf to seq_puts. Signed-off-by: Ionut Alexa Signed-off-by: Rusty Russell (removed bogus KERN_DEFAULT conversion)

module: Remove stop_machine from module unloading

2014-11-11T06:37:46Z

Remove stop_machine from module unloading by adding new reference counting algorithm. This atomic refcounter works like a semaphore, it can get (be incremented) only when the counter is not 0. When loading a module, kmodule subsystem sets the counter MODULE_REF_BASE (= 1). And when unloading the module, it subtracts MODULE_REF_BASE from the counter. If no one refers the module, the refcounter becomes 0 and we can remove the module safely. If someone referes it, we try to recover the counter by adding MODULE_REF_BASE unless the counter becomes 0, because the referrer can put the module right before recovering. If the recovering is failed, we can get the 0 refcount and it never be incremented again, it can be removed safely too. Note that __module_get() forcibly gets the module refcounter, users should use try_module_get() instead of that. Signed-off-by: Masami Hiramatsu Signed-off-by: Rusty Russell

module: Replace module_ref with atomic_t refcnt

2014-11-11T06:37:46Z

Replace module_ref per-cpu complex reference counter with an atomic_t simple refcnt. This is for code simplification. Signed-off-by: Masami Hiramatsu Signed-off-by: Rusty Russell

lib/bug: Use RCU list ops for module_bug_list

2014-11-11T06:37:46Z

Actually since module_bug_list should be used in BUG context, we may not need this. But for someone who want to use this from normal context, this makes module_bug_list an RCU list. Signed-off-by: Masami Hiramatsu Signed-off-by: Rusty Russell

module: Unlink module with RCU synchronizing instead of stop_machine

2014-11-11T06:37:45Z

Unlink module from module list with RCU synchronizing instead of using stop_machine(). Since module list is already protected by rcu, we don't need stop_machine() anymore. Signed-off-by: Masami Hiramatsu Signed-off-by: Rusty Russell