commit 6d2555cde2 upstream.
The ipmi communication is not restored after a specific version of BMC is
upgraded on our server.
The ipmi driver does not respond after printing the following log:
ipmi_ssif: Invalid response getting flags: 1c 1
I found that after entering this branch, ssif_info->ssif_state always
holds SSIF_GETTING_FLAGS and never return to IDLE.
As a result, the driver cannot be loaded, because the driver status is
checked during the unload process and must be IDLE in shutdown_ssif():
while (ssif_info->ssif_state != SSIF_IDLE)
schedule_timeout(1);
The process trigger this problem is:
1. One msg timeout and next msg start send, and call
ssif_set_need_watch().
2. ssif_set_need_watch()->watch_timeout()->start_flag_fetch() change
ssif_state to SSIF_GETTING_FLAGS.
3. In msg_done_handler() ssif_state == SSIF_GETTING_FLAGS, if an error
message is received, the second branch does not modify the ssif_state.
4. All retry action need IS_SSIF_IDLE() == True. Include retry action in
watch_timeout(), msg_done_handler(). Sending msg does not work either.
SSIF_IDLE is also checked in start_next_msg().
5. The only thing that can be triggered in the SSIF driver is
watch_timeout(), after destory_user(), this timer will stop too.
So, if enter this branch, the ssif_state will remain SSIF_GETTING_FLAGS
and can't send msg, no timer started, can't unload.
We did a comparative test before and after adding this patch, and the
result is effective.
Fixes: 259307074b ("ipmi: Add SMBus interface driver (SSIF)")
Cc: stable@vger.kernel.org
Signed-off-by: Zhang Yuchen <zhangyuchen.lcr@bytedance.com>
Message-Id: <20230412074907.80046-1-zhangyuchen.lcr@bytedance.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
44847a506e