From: Zhang Yuchen <zhangyuchen.lcr@bytedance.com>

Date: Wed, 12 Apr 2023 15:49:07 +0800

Subject: ipmi: fix SSIF not responding under certain cond.

Git-commit: 6d2555cde2918409b0331560e66f84a0ad4849c6

Patch-mainline: v6.4-rc1

References: git-fixes

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: 259307074bfc ("ipmi: Add SMBus interface driver (SSIF)")

[js] the constant is named SSIF_NORMAL in 4.*

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: Jiri Slaby <jslaby@suse.cz>

---

 drivers/char/ipmi/ipmi_ssif.c |    4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/char/ipmi/ipmi_ssif.c

+++ b/drivers/char/ipmi/ipmi_ssif.c

@@ -774,9 +774,9 @@ static void msg_done_handler(struct ssif

 		} else if (data[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2

 			   || data[1] != IPMI_GET_MSG_FLAGS_CMD) {

 			/*

-			 * Don't abort here, maybe it was a queued

-			 * response to a previous command.

+			 * Recv error response, give up.

 			 */

+			ssif_info->ssif_state = SSIF_NORMAL;

 			ipmi_ssif_unlock_cond(ssif_info, flags);

 			pr_warn(PFX "Invalid response getting flags: %x %x\n",

 				data[0], data[1]);