* Is register_cpu() now obligatory?
@ 2012-01-09 1:00 Richard Weinberger
2012-01-09 2:36 ` Randy Dunlap
0 siblings, 1 reply; 2+ messages in thread
From: Richard Weinberger @ 2012-01-09 1:00 UTC (permalink / raw)
To: linux-kernel; +Cc: gregkh, user-mode-linux-devel
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Hi!
In Linus' tree as of today UML is broken.
It's crashing because get_cpu_device() in topology_add_dev()
returns a device with an invalid kobj (address is 0x10).
The code seems to assume that each arch has to register their CPUs
using register_cpu().
Is this a regression or was UML always faulty because it did not register it's CPU?
The below patch fixes the issue for UML.
Thanks,
//richard
---
diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index bc49474..f3b43fe 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -12,7 +12,7 @@ clean-files :=
obj-y = config.o exec.o exitcode.o init_task.o irq.o ksyms.o mem.o \
physmem.o process.o ptrace.o reboot.o sigio.o \
signal.o smp.o syscall.o sysrq.o time.o tlb.o trap.o \
- um_arch.o umid.o skas/
+ um_arch.o umid.o cpu.o skas/
obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
obj-$(CONFIG_GPROF) += gprof_syms.o
diff --git a/arch/um/kernel/cpu.c b/arch/um/kernel/cpu.c
new file mode 100644
index 0000000..4914df2
--- /dev/null
+++ b/arch/um/kernel/cpu.c
@@ -0,0 +1,19 @@
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/cpu.h>
+#include <linux/percpu.h>
+
+static DEFINE_PER_CPU(struct cpu, cpu_devices);
+
+static int __init topology_init(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct cpu *c = &per_cpu(cpu_devices, cpu);
+ register_cpu(c, cpu);
+ }
+
+ return 0;
+}
+subsys_initcall(topology_init);
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: Is register_cpu() now obligatory?
2012-01-09 1:00 Is register_cpu() now obligatory? Richard Weinberger
@ 2012-01-09 2:36 ` Randy Dunlap
0 siblings, 0 replies; 2+ messages in thread
From: Randy Dunlap @ 2012-01-09 2:36 UTC (permalink / raw)
To: Richard Weinberger; +Cc: linux-kernel, gregkh, user-mode-linux-devel
On 01/08/2012 05:00 PM, Richard Weinberger wrote:
> Hi!
>
> In Linus' tree as of today UML is broken.
> It's crashing because get_cpu_device() in topology_add_dev()
> returns a device with an invalid kobj (address is 0x10).
>
> The code seems to assume that each arch has to register their CPUs
> using register_cpu().
>
> Is this a regression or was UML always faulty because it did not register it's CPU?
See Linus's comment yesterday:
https://lkml.org/lkml/2012/1/7/114
> The below patch fixes the issue for UML.
>
> Thanks,
> //richard
>
> ---
> diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
> index bc49474..f3b43fe 100644
> --- a/arch/um/kernel/Makefile
> +++ b/arch/um/kernel/Makefile
> @@ -12,7 +12,7 @@ clean-files :=
> obj-y = config.o exec.o exitcode.o init_task.o irq.o ksyms.o mem.o \
> physmem.o process.o ptrace.o reboot.o sigio.o \
> signal.o smp.o syscall.o sysrq.o time.o tlb.o trap.o \
> - um_arch.o umid.o skas/
> + um_arch.o umid.o cpu.o skas/
>
> obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
> obj-$(CONFIG_GPROF) += gprof_syms.o
> diff --git a/arch/um/kernel/cpu.c b/arch/um/kernel/cpu.c
> new file mode 100644
> index 0000000..4914df2
> --- /dev/null
> +++ b/arch/um/kernel/cpu.c
> @@ -0,0 +1,19 @@
> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/cpu.h>
> +#include <linux/percpu.h>
> +
> +static DEFINE_PER_CPU(struct cpu, cpu_devices);
> +
> +static int __init topology_init(void)
> +{
> + int cpu;
> +
> + for_each_possible_cpu(cpu) {
> + struct cpu *c = &per_cpu(cpu_devices, cpu);
> + register_cpu(c, cpu);
> + }
> +
> + return 0;
> +}
> +subsys_initcall(topology_init);
>
--
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***
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