[stgt] tgtd CPU 100% problem

[Sagi Grimberg]

On 11/07/17 16:34, 李春 wrote:
> Sorry for the wrong CC'd lists.
> Is CC'd lists correct this email?
> 
> When tgtd received the DEVICE_REMOVAL event, we found that the tgtd
> cost 100% of one CPU
> 
> When we attach to the process with gdb, we found that process run a
> infinite loop in usr/iscsi/iser.c:iser_nop_work_handler() to check if
> the conn state is STATE_FULL.
> 
> it is a infinite loop code in iser_nop_work_handler()：
> 
> ```
> list_for_each_entry(conn, &iser_conn_list, conn_list) {
> ```
> 
>   gdb show that:
> ```
> gdb attach 31629
> ...
> 3511                    if (conn->h.state != STATE_FULL)
> (gdb) l
> 3506    {
> 3507            struct iser_conn *conn;
> 3508            struct iser_task *task;
> 3509
> 3510            list_for_each_entry(conn, &iser_conn_list, conn_list) {
> 3511                    if (conn->h.state != STATE_FULL)
> 3512                            continue;
> 3513                    task = conn->nop_in_task;
> 3514                    if (!task)
> 3515                            continue;
> 
> (gdb) p iser_conn_list->next
> $1 = (struct list_head *) 0x1edc6e0
> (gdb) p iser_conn_list->next->next
> $2 = (struct list_head *) 0x1edc6e0
> (gdb) p iser_conn_list->next->next->next
> $3 = (struct list_head *) 0x1edc6e0
> 
> ```
> 
> the iser_conn_list is a endless loop.

What is &iser_conn_list address?

You should run with debug mode and see if the list is
empty or not