On Mon, Dec 25, 2006 at 05:12:57PM +0900, Akinobu Mita wrote:
> Index: 2.6-mm/drivers/infiniband/hw/ehca/ehca_irq.c
> ===================================================================
> --- 2.6-mm.orig/drivers/infiniband/hw/ehca/ehca_irq.c
> +++ 2.6-mm/drivers/infiniband/hw/ehca/ehca_irq.c
> @@ -606,13 +606,16 @@ static int comp_task(void *__cct)
>  static struct task_struct *create_comp_task(struct ehca_comp_pool *pool,
>                                           int cpu)
>  {
> +     struct task_struct *task;
>       struct ehca_cpu_comp_task *cct;
>  
>       cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
>       spin_lock_init(&cct->task_lock);
>       INIT_LIST_HEAD(&cct->cq_list);
>       init_waitqueue_head(&cct->wait_queue);
> -     cct->task = kthread_create(comp_task, cct, "ehca_comp/%d", cpu);
> +     task = kthread_create(comp_task, cct, "ehca_comp/%d", cpu);
> +     if (!IS_ERR(task))
> +             cct->task = task;
>  
>       return cct->task;
>  }

This patch is wrong. It changes to make create_comp_task() return NULL
on failure.

(BTW, all these ehca fixes are not compile tested due to luck of
cross comile environment)

Subject: [PATCH -mm] ehca: avoid crash on kthread_create() failure (v2)

This patch disallows invalid task_struct pointer returned by
kthread_create() to be written to percpu data to avoid crash.

Cc: Heiko Carstens <[EMAIL PROTECTED]>
Cc: Hoang-Nam Nguyen <[EMAIL PROTECTED]>
Cc: Christoph Raisch <[EMAIL PROTECTED]>
Signed-off-by: Akinobu Mita <[EMAIL PROTECTED]>

---
 drivers/infiniband/hw/ehca/ehca_irq.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

Index: 2.6-mm/drivers/infiniband/hw/ehca/ehca_irq.c
===================================================================
--- 2.6-mm.orig/drivers/infiniband/hw/ehca/ehca_irq.c
+++ 2.6-mm/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -606,15 +606,18 @@ static int comp_task(void *__cct)
 static struct task_struct *create_comp_task(struct ehca_comp_pool *pool,
                                            int cpu)
 {
+       struct task_struct *task;
        struct ehca_cpu_comp_task *cct;
 
        cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
        spin_lock_init(&cct->task_lock);
        INIT_LIST_HEAD(&cct->cq_list);
        init_waitqueue_head(&cct->wait_queue);
-       cct->task = kthread_create(comp_task, cct, "ehca_comp/%d", cpu);
+       task = kthread_create(comp_task, cct, "ehca_comp/%d", cpu);
+       if (!IS_ERR(task))
+               cct->task = task;
 
-       return cct->task;
+       return task;
 }
 
 static void destroy_comp_task(struct ehca_comp_pool *pool,
@@ -684,8 +687,10 @@ static int comp_pool_callback(struct not
        case CPU_UP_CANCELED:
                ehca_gen_dbg("CPU: %x (CPU_CANCELED)", cpu);
                cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
-               kthread_bind(cct->task, any_online_cpu(cpu_online_map));
-               destroy_comp_task(pool, cpu);
+               if (cct->task) {
+                       kthread_bind(cct->task, any_online_cpu(cpu_online_map));
+                       destroy_comp_task(pool, cpu);
+               }
                break;
        case CPU_ONLINE:
                ehca_gen_dbg("CPU: %x (CPU_ONLINE)", cpu);
-
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