-stable review patch. If anyone has any objections, please let us know.
------------------
From: Brian Uhrain <[email protected]> says:
I've encountered two problems with 2.6.16 and newer kernels on my API CS20
(dual 833MHz Alpha 21264b processors). The first is the kernel OOPSing
because of a NULL pointer dereference while trying to populate SysFS with the
CPU information. The other is that only one processor was being brought up.
I've included a small Alpha-specific patch that fixes both problems.
The first problem was caused by the CPUs never being properly registered using
register_cpu(), the way it's done on other architectures.
The second problem has to do with the removal of hwrpb_cpu_present_mask in
arch/alpha/kernel/smp.c. In setup_smp() in the 2.6.15 kernel sources,
hwrpb_cpu_present_mask has a bit set for each processor that is probed, and
afterwards cpu_present_mask is set to the cpumask for the boot CPU. In the
same function of the same file in the 2.6.16 sources, instead of
hwrpb_cpu_present_mask being set, cpu_possible_map is updated for each probed
CPU. cpu_present_mask is still set to the cpumask of the boot CPU afterwards.
The problem lies in include/asm-alpha/smp.h, where cpu_possible_map is
#define'd to be cpu_present_mask.
Cleanups from: Ivan Kokshaysky <[email protected]>
- cpu_present_mask and cpu_possible_map are essentially the same thing
on alpha, as it doesn't support CPU hotplug;
- allocate "struct cpu" only for present CPUs, like sparc64 does.
Static array of "struct cpu" is just a waste of memory.
Signed-off-by: Brian Uhrain <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/alpha/kernel/setup.c | 17 +++++++++++++++++
arch/alpha/kernel/smp.c | 8 +++-----
2 files changed, 20 insertions(+), 5 deletions(-)
--- linux-2.6.16.5.orig/arch/alpha/kernel/setup.c
+++ linux-2.6.16.5/arch/alpha/kernel/setup.c
@@ -24,6 +24,7 @@
#include <linux/config.h> /* CONFIG_ALPHA_LCA etc */
#include <linux/mc146818rtc.h>
#include <linux/console.h>
+#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/string.h>
@@ -477,6 +478,22 @@ page_is_ram(unsigned long pfn)
#undef PFN_PHYS
#undef PFN_MAX
+static int __init
+register_cpus(void)
+{
+ int i;
+
+ for_each_possible_cpu(i) {
+ struct cpu *p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+ register_cpu(p, i, NULL);
+ }
+ return 0;
+}
+
+arch_initcall(register_cpus);
+
void __init
setup_arch(char **cmdline_p)
{
--- linux-2.6.16.5.orig/arch/alpha/kernel/smp.c
+++ linux-2.6.16.5/arch/alpha/kernel/smp.c
@@ -439,7 +439,7 @@ setup_smp(void)
if ((cpu->flags & 0x1cc) == 0x1cc) {
smp_num_probed++;
/* Assume here that "whami" == index */
- cpu_set(i, cpu_possible_map);
+ cpu_set(i, cpu_present_mask);
cpu->pal_revision = boot_cpu_palrev;
}
@@ -450,9 +450,8 @@ setup_smp(void)
}
} else {
smp_num_probed = 1;
- cpu_set(boot_cpuid, cpu_possible_map);
+ cpu_set(boot_cpuid, cpu_present_mask);
}
- cpu_present_mask = cpumask_of_cpu(boot_cpuid);
printk(KERN_INFO "SMP: %d CPUs probed -- cpu_present_mask = %lx\n",
smp_num_probed, cpu_possible_map.bits[0]);
@@ -488,9 +487,8 @@ void __devinit
smp_prepare_boot_cpu(void)
{
/*
- * Mark the boot cpu (current cpu) as both present and online
+ * Mark the boot cpu (current cpu) as online
*/
- cpu_set(smp_processor_id(), cpu_present_mask);
cpu_set(smp_processor_id(), cpu_online_map);
}
--
-
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