ipmi: fix long wait in unload when IPMI disconnect

stable inclusion
from stable-v5.10.163
commit 4e17819cb3023ef40dd4a1d1694d631cca69df04
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7PJ9N

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4e17819cb3023ef40dd4a1d1694d631cca69df04



----------------------------------------------------

commit f6f1234d upstream.

When fixing the problem mentioned in PATCH1, we also found
the following problem:

If the IPMI is disconnected and in the sending process, the
uninstallation driver will be stuck for a long time.

The main problem is that uninstalling the driver waits for curr_msg to
be sent or HOSED. After stopping tasklet, the only place to trigger the
timeout mechanism is the circular poll in shutdown_smi.

The poll function delays 10us and calls smi_event_handler(smi_info,10).
Smi_event_handler deducts 10us from kcs->ibf_timeout.

But the poll func is followed by schedule_timeout_uninterruptible(1).
The time consumed here is not counted in kcs->ibf_timeout.

So when 10us is deducted from kcs->ibf_timeout, at least 1 jiffies has
actually passed. The waiting time has increased by more than a
hundredfold.

Now instead of calling poll(). call smi_event_handler() directly and
calculate the elapsed time.

For verification, you can directly use ebpf to check the kcs->
ibf_timeout for each call to kcs_event() when IPMI is disconnected.
Decrement at normal rate before unloading. The decrement rate becomes
very slow after unloading.

  $ bpftrace -e 'kprobe:kcs_event {printf("kcs->ibftimeout : %d\n",
      *(arg0+584));}'

Signed-off-by: Zhang Yuchen <zhangyuchen.lcr@bytedance.com>
Message-Id: <20221007092617.87597-3-zhangyuchen.lcr@bytedance.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: zhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>