x86, kexec: Make sure to stop all CPUs before exiting the kernel

x86 smp_ops now has a new op, stop_other_cpus which takes a parameter
"wait" this allows the caller to specify if it wants to stop until all
the cpus have processed the stop IPI.  This is required specifically
for the kexec case where we should wait for all the cpus to be stopped
before starting the new kernel.  We now wait for the cpus to stop in
all cases except for panic/kdump where we expect things to be broken
and we are doing our best to make things work anyway.

This patch fixes a legitimate regression, which was introduced during
2.6.30, by commit id 4ef702c10b5df18ab04921fc252c26421d4d6c75.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
LKML-Reference: <1286833028.1372.20.camel@ank32.eng.vmware.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: <stable@kernel.org> v2.6.30-36
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 4cfc908240684c561b4554281c36850643fc139f..4c2f63c7fc1b2ec071d3d32465f389a6d9df24dd 100644 (file)
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -50,7 +50,7 @@ struct smp_ops {
        void (*smp_prepare_cpus)(unsigned max_cpus);
        void (*smp_cpus_done)(unsigned max_cpus);
 
-       void (*smp_send_stop)(void);
+       void (*stop_other_cpus)(int wait);
        void (*smp_send_reschedule)(int cpu);
 
        int (*cpu_up)(unsigned cpu);
@@ -73,7 +73,12 @@ extern struct smp_ops smp_ops;
 
 static inline void smp_send_stop(void)
 {
-       smp_ops.smp_send_stop();
+       smp_ops.stop_other_cpus(0);
+}
+
+static inline void stop_other_cpus(void)
+{
+       smp_ops.stop_other_cpus(1);
 }
 
 static inline void smp_prepare_boot_cpu(void)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index e3af342fe83ae7a57b8f6db6de4fb9541c4ab15e..76a0d715a0319f227f11650940460ade011a5480 100644 (file)
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -641,7 +641,7 @@ void native_machine_shutdown(void)
        /* O.K Now that I'm on the appropriate processor,
         * stop all of the others.
         */
-       smp_send_stop();
+       stop_other_cpus();
 #endif
 
        lapic_shutdown();

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index d801210945d6f5d93e3a8c672243a67792bca3cd..513deac7228d2262b3e07c2915c042a791abb7f8 100644 (file)
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -159,10 +159,10 @@ asmlinkage void smp_reboot_interrupt(void)
        irq_exit();
 }
 
-static void native_smp_send_stop(void)
+static void native_stop_other_cpus(int wait)
 {
        unsigned long flags;
-       unsigned long wait;
+       unsigned long timeout;
 
        if (reboot_force)
                return;
@@ -179,9 +179,12 @@ static void native_smp_send_stop(void)
        if (num_online_cpus() > 1) {
                apic->send_IPI_allbutself(REBOOT_VECTOR);
 
-               /* Don't wait longer than a second */
-               wait = USEC_PER_SEC;
-               while (num_online_cpus() > 1 && wait--)
+               /*
+                * Don't wait longer than a second if the caller
+                * didn't ask us to wait.
+                */
+               timeout = USEC_PER_SEC;
+               while (num_online_cpus() > 1 && (wait || timeout--))
                        udelay(1);
        }
 
@@ -227,7 +230,7 @@ struct smp_ops smp_ops = {
        .smp_prepare_cpus       = native_smp_prepare_cpus,
        .smp_cpus_done          = native_smp_cpus_done,
 
-       .smp_send_stop          = native_smp_send_stop,
+       .stop_other_cpus        = native_stop_other_cpus,
        .smp_send_reschedule    = native_smp_send_reschedule,
 
        .cpu_up                 = native_cpu_up,

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 7d46c84414188bf401777e4d65a9652e5cc09fa5..44f80861382f82f466491de34a5951e1ce4663e0 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1018,7 +1018,7 @@ static void xen_reboot(int reason)
        struct sched_shutdown r = { .reason = reason };
 
 #ifdef CONFIG_SMP
-       smp_send_stop();
+       stop_other_cpus();
 #endif
 
        if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 25f232b18a823a5e3f015c2dfac4b38a39dcb2ed..f4d01003146581c1f58cf4835ed989de7854def5 100644 (file)
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -400,9 +400,9 @@ static void stop_self(void *v)
        BUG();
 }
 
-static void xen_smp_send_stop(void)
+static void xen_stop_other_cpus(int wait)
 {
-       smp_call_function(stop_self, NULL, 0);
+       smp_call_function(stop_self, NULL, wait);
 }
 
 static void xen_smp_send_reschedule(int cpu)
@@ -470,7 +470,7 @@ static const struct smp_ops xen_smp_ops __initdata = {
        .cpu_disable = xen_cpu_disable,
        .play_dead = xen_play_dead,
 
-       .smp_send_stop = xen_smp_send_stop,
+       .stop_other_cpus = xen_stop_other_cpus,
        .smp_send_reschedule = xen_smp_send_reschedule,
 
        .send_call_func_ipi = xen_smp_send_call_function_ipi,