[PATCH] hotplug/cpu: Extend start/stop cpumap lock scope
From: Michael Bringmann <hidden>
Date: 2018-10-13 22:06:56
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
The PPC mobility code may receive DLPAR CPU add/remove requests to perform CPU changes at any time, including during LPAR migration or RTAS requests or SMT changes. When the operations are received concurrently, there is an opportunity for DLPAR CPU remove requests and other requests to overlap, and for one of the requests to be interrupted after some shared state has been modified. This patch changes the duration for which cpu maps updates are suppressed during DLPAR CPU operations made by 'drmgr' are suppressed to reduce the period in which changes to shared state may occur. Signed-off-by: Michael Bringmann <redacted> --- arch/powerpc/platforms/pseries/hotplug-cpu.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 2f8e621..fce46c56 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c@@ -356,7 +356,6 @@ static int dlpar_online_cpu(struct device_node *dn) nthreads = len / sizeof(u32); - cpu_maps_update_begin(); for (i = 0; i < nthreads; i++) { thread = be32_to_cpu(intserv[i]); for_each_present_cpu(cpu) {
@@ -378,7 +377,6 @@ static int dlpar_online_cpu(struct device_node *dn) printk(KERN_WARNING "Could not find cpu to online " "with physical id 0x%x\n", thread); } - cpu_maps_update_done(); out: return rc;
@@ -523,7 +521,6 @@ static int dlpar_offline_cpu(struct device_node *dn) nthreads = len / sizeof(u32); - cpu_maps_update_begin(); for (i = 0; i < nthreads; i++) { thread = be32_to_cpu(intserv[i]); for_each_present_cpu(cpu) {
@@ -559,7 +556,6 @@ static int dlpar_offline_cpu(struct device_node *dn) if (cpu == num_possible_cpus()) printk(KERN_WARNING "Could not find cpu to offline with physical id 0x%x\n", thread); } - cpu_maps_update_done(); out: return rc;
@@ -811,6 +807,7 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog) drc_index = hp_elog->_drc_u.drc_index; lock_device_hotplug(); + cpu_maps_update_begin(); switch (hp_elog->action) { case PSERIES_HP_ELOG_ACTION_REMOVE:
@@ -835,6 +832,7 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog) break; } + cpu_maps_update_done(); unlock_device_hotplug(); return rc; }
@@ -850,7 +848,9 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count) if (rc) return -EINVAL; + cpu_maps_update_begin(); rc = dlpar_cpu_add(drc_index); + cpu_maps_update_done(); return rc ? rc : count; }
@@ -871,7 +871,9 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count) return -EINVAL; } + cpu_maps_update_begin(); rc = dlpar_cpu_remove(dn, drc_index); + cpu_maps_update_done(); of_node_put(dn); return rc ? rc : count;