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]);