[PATCH v6 23/46] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline
From: Srivatsa S. Bhat <hidden>
Date: 2013-02-18 12:51:56
Also in:
linux-arch, linux-pm, linuxppc-dev, lkml, netdev
Subsystem:
infiniband subsystem, the rest · Maintainers:
Jason Gunthorpe, Leon Romanovsky, Linus Torvalds
Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_disable() to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: Roland Dreier <roland@kernel.org> Signed-off-by: Srivatsa S. Bhat <redacted> --- drivers/infiniband/hw/ehca/ehca_irq.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index 8615d7c..d61936c 100644
--- a/drivers/infiniband/hw/ehca/ehca_irq.c
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c@@ -43,6 +43,7 @@ #include <linux/slab.h> #include <linux/smpboot.h> +#include <linux/cpu.h> #include "ehca_classes.h" #include "ehca_irq.h"
@@ -653,6 +654,9 @@ void ehca_tasklet_eq(unsigned long data) ehca_process_eq((struct ehca_shca*)data, 1); } +/* + * Must be called under get_online_cpus_atomic() and put_online_cpus_atomic(). + */ static int find_next_online_cpu(struct ehca_comp_pool *pool) { int cpu;
@@ -703,6 +707,7 @@ static void queue_comp_task(struct ehca_cq *__cq) int cq_jobs; unsigned long flags; + get_online_cpus_atomic(); cpu_id = find_next_online_cpu(pool); BUG_ON(!cpu_online(cpu_id));
@@ -720,6 +725,7 @@ static void queue_comp_task(struct ehca_cq *__cq) BUG_ON(!cct || !thread); } __queue_comp_task(__cq, cct, thread); + put_online_cpus_atomic(); } static void run_comp_task(struct ehca_cpu_comp_task *cct)
@@ -759,6 +765,7 @@ static void comp_task_park(unsigned int cpu) list_splice_init(&cct->cq_list, &list); spin_unlock_irq(&cct->task_lock); + get_online_cpus_atomic(); cpu = find_next_online_cpu(pool); target = per_cpu_ptr(pool->cpu_comp_tasks, cpu); thread = *per_cpu_ptr(pool->cpu_comp_threads, cpu);
@@ -768,6 +775,7 @@ static void comp_task_park(unsigned int cpu) __queue_comp_task(cq, target, thread); } spin_unlock_irq(&target->task_lock); + put_online_cpus_atomic(); } static void comp_task_stop(unsigned int cpu, bool online)