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SubjectRe: [PATCH rdma-next 1/5] RDMA/hns: Implement the disassociate_ucontext API
On Thu, May 17, 2018 at 04:02:49PM +0800, Wei Hu (Xavier) wrote:
> This patch Implements the IB core disassociate_ucontext API.
>
> Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
> drivers/infiniband/hw/hns/hns_roce_main.c | 36 +++++++++++++++++++++++++++++++
> 1 file changed, 36 insertions(+)
>
> diff --git a/drivers/infiniband/hw/hns/hns_roce_main.c b/drivers/infiniband/hw/hns/hns_roce_main.c
> index 96fb6a9..7fafe9d 100644
> +++ b/drivers/infiniband/hw/hns/hns_roce_main.c
> @@ -33,6 +33,9 @@
> #include <linux/acpi.h>
> #include <linux/of_platform.h>
> #include <linux/module.h>
> +#include <linux/sched.h>
> +#include <linux/sched/mm.h>
> +#include <linux/sched/task.h>
> #include <rdma/ib_addr.h>
> #include <rdma/ib_smi.h>
> #include <rdma/ib_user_verbs.h>
> @@ -422,6 +425,38 @@ static int hns_roce_port_immutable(struct ib_device *ib_dev, u8 port_num,
> return 0;
> }
>
> +static void hns_roce_disassociate_ucontext(struct ib_ucontext *ibcontext)
> +{
> + struct task_struct *process;
> + struct mm_struct *mm;
> +
> + process = get_pid_task(ibcontext->tgid, PIDTYPE_PID);
> + if (!process)
> + return;
> +
> + mm = get_task_mm(process);
> + if (!mm) {
> + pr_info("no mm, disassociate ucontext is pending task termination\n");
> + while (1) {
> + put_task_struct(process);
> + usleep_range(1000, 2000);
> + process = get_pid_task(ibcontext->tgid, PIDTYPE_PID);
> + if (!process || process->state == TASK_DEAD) {
> + pr_info("disassociate ucontext done, task was terminated\n");
> + /* if task was dead, need to release the task
> + * struct.
> + */
> + if (process)
> + put_task_struct(process);
> + return;
> + }
> + }
> + }

I don't want to see this boilerplate code copied into every
driver. Hoist it into the core code, have the disassociate driver callback
accept a mm_struct parameter, and refactor the other drivers using this.

> + mmput(mm);
> + put_task_struct(process);
> +}

This can't be right, disassociate requires the driver to replace all
the mmaps it make to user space with the 0 page, I see hns does use
mmaps, so it must zap them here.

Jason

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