linux/kernel/stop_machine.c, branch v2.6.28

stop_machine: fix race with return value (fixes Bug #11989)

2008-11-16T23:09:52Z

Bug #11989: Suspend failure on NForce4-based boards due to chanes in stop_machine We should not access active.fnret outside the lock; in theory the next stop_machine could overwrite it. Signed-off-by: Rusty Russell Tested-by: "Rafael J. Wysocki" Signed-off-by: Linus Torvalds

Revert "Call init_workqueues before pre smp initcalls."

2008-10-26T02:53:38Z

This reverts commit a802dd0eb5fc97a50cf1abb1f788a8f6cc5db635 by moving the call to init_workqueues() back where it belongs - after SMP has been initialized. It also moves stop_machine_init() - which needs workqueues - to a later phase using a core_initcall() instead of early_initcall(). That should satisfy all ordering requirements, and was apparently the reason why init_workqueues() was moved to be too early. Cc: Heiko Carstens Cc: Rusty Russell Signed-off-by: Linus Torvalds

stop_machine: fix error code handling on multiple cpus

2008-10-21T23:00:26Z

Using |= for updating a value which might be updated on several cpus concurrently will not always work since we need to make sure that the update happens atomically. To fix this just use a write if the called function returns an error code on a cpu. We end up writing the error code of an arbitrary cpu if multiple ones fail but that should be sufficient. Signed-off-by: Heiko Carstens Signed-off-by: Rusty Russell

stop_machine: use workqueues instead of kernel threads

2008-10-21T23:00:26Z

Convert stop_machine to a workqueue based approach. Instead of using kernel threads for stop_machine we now use a an rt workqueue to synchronize all cpus. This has the advantage that all needed per cpu threads are already created when stop_machine gets called. And therefore a call to stop_machine won't fail anymore. This is needed for s390 which needs a mechanism to synchronize all cpus without allocating any memory. As Rusty pointed out free_module() needs a non-failing stop_machine interface as well. As a side effect the stop_machine code gets simplified. Signed-off-by: Heiko Carstens Signed-off-by: Rusty Russell

stop_machine: remove unused variable

2008-08-12T07:52:55Z

Signed-off-by: Li Zefan Signed-off-by: Rusty Russell

stop_machine(): stop_machine_run() changed to use cpu mask

2008-07-28T02:16:30Z

Instead of a "cpu" arg with magic values NR_CPUS (any cpu) and ~0 (all cpus), pass a cpumask_t. Allow NULL for the common case (where we don't care which CPU the function is run on): temporary cpumask_t's are usually considered bad for stack space. This deprecates stop_machine_run, to be removed soon when all the callers are dead. Signed-off-by: Rusty Russell

Simplify stop_machine

2008-07-28T02:16:29Z

stop_machine creates a kthread which creates kernel threads. We can create those threads directly and simplify things a little. Some care must be taken with CPU hotunplug, which has special needs, but that code seems more robust than it was in the past. Signed-off-by: Rusty Russell Acked-by: Christian Borntraeger

stop_machine: add ALL_CPUS option

2008-07-28T02:16:28Z

-allow stop_mahcine_run() to call a function on all cpus. Calling stop_machine_run() with a 'ALL_CPUS' invokes this new behavior. stop_machine_run() proceeds as normal until the calling cpu has invoked 'fn'. Then, we tell all the other cpus to call 'fn'. Signed-off-by: Jason Baron Signed-off-by: Mathieu Desnoyers Signed-off-by: Rusty Russell CC: Adrian Bunk CC: Andi Kleen CC: Alexey Dobriyan CC: Christoph Hellwig CC: mingo@elte.hu CC: akpm@osdl.org

cpumask: Replace cpumask_of_cpu with cpumask_of_cpu_ptr

2008-07-18T20:02:57Z

* This patch replaces the dangerous lvalue version of cpumask_of_cpu with new cpumask_of_cpu_ptr macros. These are patterned after the node_to_cpumask_ptr macros. In general terms, if there is a cpumask_of_cpu_map[] then a pointer to the cpumask_of_cpu_map[cpu] entry is used. The cpumask_of_cpu_map is provided when there is a large NR_CPUS count, reducing greatly the amount of code generated and stack space used for cpumask_of_cpu(). The pointer to the cpumask_t value is needed for calling set_cpus_allowed_ptr() to reduce the amount of stack space needed to pass the cpumask_t value. If there isn't a cpumask_of_cpu_map[], then a temporary variable is declared and filled in with value from cpumask_of_cpu(cpu) as well as a pointer variable pointing to this temporary variable. Afterwards, the pointer is used to reference the cpumask value. The compiler will optimize out the extra dereference through the pointer as well as the stack space used for the pointer, resulting in identical code. A good example of the orthogonal usages is in net/sunrpc/svc.c: case SVC_POOL_PERCPU: { unsigned int cpu = m->pool_to[pidx]; cpumask_of_cpu_ptr(cpumask, cpu); *oldmask = current->cpus_allowed; set_cpus_allowed_ptr(current, cpumask); return 1; } case SVC_POOL_PERNODE: { unsigned int node = m->pool_to[pidx]; node_to_cpumask_ptr(nodecpumask, node); *oldmask = current->cpus_allowed; set_cpus_allowed_ptr(current, nodecpumask); return 1; } Signed-off-by: Mike Travis Signed-off-by: Ingo Molnar

sched: add new API sched_setscheduler_nocheck: add a flag to control access checks

2008-06-23T20:57:56Z

Hidehiro Kawai noticed that sched_setscheduler() can fail in stop_machine: it calls sched_setscheduler() from insmod, which can have CAP_SYS_MODULE without CAP_SYS_NICE. Two cases could have failed, so are changed to sched_setscheduler_nocheck: kernel/softirq.c:cpu_callback() - CPU hotplug callback kernel/stop_machine.c:__stop_machine_run() - Called from various places, including modprobe() Signed-off-by: Rusty Russell Cc: Jeremy Fitzhardinge Cc: Hidehiro Kawai Cc: Andrew Morton Cc: linux-mm@kvack.org Cc: sugita Cc: Satoshi OSHIMA Signed-off-by: Ingo Molnar