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Wysocki" Cc: Jaroslav Pulchart , Guenter Roeck , Igor Raits , linux-acpi@vger.kernel.org, linux-hwmon@vger.kernel.org, Daniel Secik , Zdenek Pesek , Jiri Jurica , Huisong Li , Corey Minyard Subject: [PATCH 3/3] ipmi:si: Fix check for a misbehaving BMC Date: Fri, 13 Feb 2026 00:52:15 -0600 Message-ID: <20260213065351.915707-4-corey@minyard.net> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260213065351.915707-1-corey@minyard.net> References: <20260213065351.915707-1-corey@minyard.net> Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit There is a race on checking the state in the sender, it needs to be checked under a lock. But you also need a check to avoid issues with a misbehaving BMC for run to completion mode. So leave the check at the beginning for run to completion, and add a check under the lock to avoid the race. Reported-by: Rafael J. Wysocki Fixes: bc3a9d217755 ("ipmi:si: Gracefully handle if the BMC is non-functional") Signed-off-by: Corey Minyard --- drivers/char/ipmi/ipmi_si_intf.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c index 3667033fcc51..6eda61664aaa 100644 --- a/drivers/char/ipmi/ipmi_si_intf.c +++ b/drivers/char/ipmi/ipmi_si_intf.c @@ -924,9 +924,14 @@ static int sender(void *send_info, struct ipmi_smi_msg *msg) { struct smi_info *smi_info = send_info; unsigned long flags; + int rv = IPMI_CC_NO_ERROR; debug_timestamp(smi_info, "Enqueue"); + /* + * Check here for run to completion mode. A check under lock is + * later. + */ if (smi_info->si_state == SI_HOSED) return IPMI_BUS_ERR; @@ -940,18 +945,15 @@ static int sender(void *send_info, struct ipmi_smi_msg *msg) } spin_lock_irqsave(&smi_info->si_lock, flags); - /* - * The following two lines don't need to be under the lock for - * the lock's sake, but they do need SMP memory barriers to - * avoid getting things out of order. We are already claiming - * the lock, anyway, so just do it under the lock to avoid the - * ordering problem. - */ - BUG_ON(smi_info->waiting_msg); - smi_info->waiting_msg = msg; - check_start_timer_thread(smi_info); + if (smi_info->si_state == SI_HOSED) { + rv = IPMI_BUS_ERR; + } else { + BUG_ON(smi_info->waiting_msg); + smi_info->waiting_msg = msg; + check_start_timer_thread(smi_info); + } spin_unlock_irqrestore(&smi_info->si_lock, flags); - return IPMI_CC_NO_ERROR; + return rv; } static void set_run_to_completion(void *send_info, bool i_run_to_completion) -- 2.43.0