Prev: [108/117] power_meter: acpi_device_class "power_meter_resource" too long
Next: [GIT PULL 00/10] perf fixes and improvements
From: Greg KH on 10 May 2010 19:30
2.6.33-stable review patch. If anyone has any objections, please let us know.

------------------

From: Vaidyanathan Srinivasan <svaidy(a)linux.vnet.ibm.com>

commit 8dbce53cc249a76e9450708d291fce5a7e29c6a1 upstream.

Cpu hotplug (offline) without dlpar operation will place cpu
in cede state and the extended_cede_processor() function will
return when resumed.

Kernel stack pointer needs to be reset before
start_secondary() is called to continue the online operation.

Added new function start_secondary_resume() to do the above
steps.

Signed-off-by: Vaidyanathan Srinivasan <svaidy(a)linux.vnet.ibm.com>
Cc: Gautham R Shenoy <ego(a)in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh(a)kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
arch/powerpc/kernel/head_64.S | 11 +++++++++++
arch/powerpc/platforms/pseries/hotplug-cpu.c | 9 ++++-----
arch/powerpc/platforms/pseries/offline_states.h | 1 +
3 files changed, 16 insertions(+), 5 deletions(-)

--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -615,6 +615,17 @@ _GLOBAL(start_secondary_prolog)
std r3,0(r1) /* Zero the stack frame pointer */
bl .start_secondary
b .
+/*
+ * Reset stack pointer and call start_secondary
+ * to continue with online operation when woken up
+ * from cede in cpu offline.
+ */
+_GLOBAL(start_secondary_resume)
+ ld r1,PACAKSAVE(r13) /* Reload kernel stack pointer */
+ li r3,0
+ std r3,0(r1) /* Zero the stack frame pointer */
+ bl .start_secondary
+ b .
#endif

/*
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -146,12 +146,11 @@ static void pseries_mach_cpu_die(void)
unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));

/*
- * NOTE: Calling start_secondary() here for now to
- * start new context.
- * However, need to do it cleanly by resetting the
- * stack pointer.
+ * Call to start_secondary_resume() will not return.
+ * Kernel stack will be reset and start_secondary()
+ * will be called to continue the online operation.
*/
- start_secondary();
+ start_secondary_resume();

} else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {

--- a/arch/powerpc/platforms/pseries/offline_states.h
+++ b/arch/powerpc/platforms/pseries/offline_states.h
@@ -35,4 +35,5 @@ static inline void set_default_offline_s

extern enum cpu_state_vals get_preferred_offline_state(int cpu);
extern int start_secondary(void);
+extern void start_secondary_resume(void);
#endif


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: [108/117] power_meter: acpi_device_class "power_meter_resource" too long
Next: [GIT PULL 00/10] perf fixes and improvements