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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2013-03-20 15:31:29 +0530
committerTony Luck <tony.luck@intel.com>2013-04-02 14:04:01 -0700
commit7a0c819d28f5c91955854e048766d6afef7c8a3d (patch)
tree539295c0861de4e4e971f8895c13816df975fbe2 /arch/x86/kernel
parent07961ac7c0ee8b546658717034fe692fd12eefa9 (diff)
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x86/mce: Rework cmci_rediscover() to play well with CPU hotplug
Dave Jones reports that offlining a CPU leads to this trace: numa_remove_cpu cpu 1 node 0: mask now 0,2-3 smpboot: CPU 1 is now offline BUG: using smp_processor_id() in preemptible [00000000] code: cpu-offline.sh/10591 caller is cmci_rediscover+0x6a/0xe0 Pid: 10591, comm: cpu-offline.sh Not tainted 3.9.0-rc3+ #2 Call Trace: [<ffffffff81333bbd>] debug_smp_processor_id+0xdd/0x100 [<ffffffff8101edba>] cmci_rediscover+0x6a/0xe0 [<ffffffff815f5b9f>] mce_cpu_callback+0x19d/0x1ae [<ffffffff8160ea66>] notifier_call_chain+0x66/0x150 [<ffffffff8107ad7e>] __raw_notifier_call_chain+0xe/0x10 [<ffffffff8104c2e3>] cpu_notify+0x23/0x50 [<ffffffff8104c31e>] cpu_notify_nofail+0xe/0x20 [<ffffffff815ef082>] _cpu_down+0x302/0x350 [<ffffffff815ef106>] cpu_down+0x36/0x50 [<ffffffff815f1c9d>] store_online+0x8d/0xd0 [<ffffffff813edc48>] dev_attr_store+0x18/0x30 [<ffffffff81226eeb>] sysfs_write_file+0xdb/0x150 [<ffffffff811adfb2>] vfs_write+0xa2/0x170 [<ffffffff811ae16c>] sys_write+0x4c/0xa0 [<ffffffff81613019>] system_call_fastpath+0x16/0x1b However, a look at cmci_rediscover shows that it can be simplified quite a bit, apart from solving the above issue. It invokes functions that take spin locks with interrupts disabled, and hence it can run in atomic context. Also, it is run in the CPU_POST_DEAD phase, so the dying CPU is already dead and out of the cpu_online_mask. So take these points into account and simplify the code, and thereby also fix the above issue. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/cpu/mcheck/mce.c2
-rw-r--r--arch/x86/kernel/cpu/mcheck/mce_intel.c25
2 files changed, 6 insertions, 21 deletions
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 7bc1263..9239504 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -2358,7 +2358,7 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
if (action == CPU_POST_DEAD) {
/* intentionally ignoring frozen here */
- cmci_rediscover(cpu);
+ cmci_rediscover();
}
return NOTIFY_OK;
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c
index 402c454..ae1697c 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c
@@ -285,39 +285,24 @@ void cmci_clear(void)
raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
}
-static long cmci_rediscover_work_func(void *arg)
+static void cmci_rediscover_work_func(void *arg)
{
int banks;
/* Recheck banks in case CPUs don't all have the same */
if (cmci_supported(&banks))
cmci_discover(banks);
-
- return 0;
}
-/*
- * After a CPU went down cycle through all the others and rediscover
- * Must run in process context.
- */
-void cmci_rediscover(int dying)
+/* After a CPU went down cycle through all the others and rediscover */
+void cmci_rediscover(void)
{
- int cpu, banks;
+ int banks;
if (!cmci_supported(&banks))
return;
- for_each_online_cpu(cpu) {
- if (cpu == dying)
- continue;
-
- if (cpu == smp_processor_id()) {
- cmci_rediscover_work_func(NULL);
- continue;
- }
-
- work_on_cpu(cpu, cmci_rediscover_work_func, NULL);
- }
+ on_each_cpu(cmci_rediscover_work_func, NULL, 1);
}
/*