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authorSrivatsa Vaddagiri <vatsa@in.ibm.com>2006-03-16 23:04:06 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-17 07:51:25 -0800
commit82c3c03a4096badd026c6e337f3c5dde020e9ec6 (patch)
treed22aa75410eb3b2bc7865f6dc6ce6c111c103bc9
parent8532159f5521ba24e697f0d25970ae89ff62a1f2 (diff)
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[PATCH] x86: check for online cpus before bringing them up
Bryce reported a bug wherein offlining CPU0 (on x86 box) and then subsequently onlining it resulted in a lockup. On x86, CPU0 is never offlined. The subsequent attempt to online CPU0 doesn't take that into account. It actually tries to bootup the already booted CPU. Following patch fixes the problem (as acknowledged by Bryce). Please consider for inclusion in 2.6.16. Check if cpu is already online. Signed-off-by: Srivatsa Vaddagiri <vatsa@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/smpboot.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index eba7f53f8b4..7007e178379 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -1029,6 +1029,16 @@ int __devinit smp_prepare_cpu(int cpu)
int apicid, ret;
lock_cpu_hotplug();
+
+ /*
+ * On x86, CPU0 is never offlined. Trying to bring up an
+ * already-booted CPU will hang. So check for that case.
+ */
+ if (cpu_online(cpu)) {
+ ret = -EINVAL;
+ goto exit;
+ }
+
apicid = x86_cpu_to_apicid[cpu];
if (apicid == BAD_APICID) {
ret = -ENODEV;