Re: [PATCH 2/3] powerpc/pseries/mobility: prevent cpu hotplug during DT update
From: Gautham R Shenoy <hidden>
Date: 2019-06-13 16:57:14
Hello Nathan, On Wed, Jun 12, 2019 at 10:19 AM Nathan Lynch [off-list ref] wrote:
CPU online/offline code paths are sensitive to parts of the device
tree (various cpu node properties, cache nodes) that can be changed as
a result of a migration.
Prevent CPU hotplug while the device tree potentially is inconsistent.
Fixes: 410bccf97881 ("powerpc/pseries: Partition migration in the kernel")
Signed-off-by: Nathan Lynch <redacted>Audited the callbacks of of_reconfig_notify(). We are fine with respect to CPU-Hotplug locking. Reviewed-by: Gautham R. Shenoy <redacted>
quoted hunk ↗ jump to hunk
--- arch/powerpc/platforms/pseries/mobility.c | 9 +++++++++ 1 file changed, 9 insertions(+)diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c index 88925f8ca8a0..edc1ec408589 100644 --- a/arch/powerpc/platforms/pseries/mobility.c +++ b/arch/powerpc/platforms/pseries/mobility.c@@ -9,6 +9,7 @@ * 2 as published by the Free Software Foundation. */ +#include <linux/cpu.h> #include <linux/kernel.h> #include <linux/kobject.h> #include <linux/smp.h>@@ -338,11 +339,19 @@ void post_mobility_fixup(void) if (rc) printk(KERN_ERR "Post-mobility activate-fw failed: %d\n", rc); + /* + * We don't want CPUs to go online/offline while the device + * tree is being updated. + */ + cpus_read_lock(); + rc = pseries_devicetree_update(MIGRATION_SCOPE); if (rc) printk(KERN_ERR "Post-mobility device tree update " "failed: %d\n", rc); + cpus_read_unlock(); + /* Possibly switch to a new RFI flush type */ pseries_setup_rfi_flush(); --2.20.1
-- Thanks and Regards gautham.