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    SubjectRe: [PATCH -mm] ehca: avoid crash on kthread_create() failure
    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 <heiko.carstens@de.ibm.com>
    Cc: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
    Cc: Christoph Raisch <raisch@de.ibm.com>
    Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

    ---
    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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