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Date: Tue, 21 Aug 2018 17:14:43 -0500
From: Andrew Banman <abanman@....com>
To: Corey Minyard <minyard@....org>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: abanman@....com, justin.ernst@....com, rja@....com,
frank.ramsay@....com, openipmi-developer@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: [RFC] IPMI state machine regression
Dear IPMI supporters,
We observe a window in IPMI BT's opportunistic get capabilities request,
wherein GET_DEVICE_GUID and GET_DEVICE_ID requests may start while the BT state
machine is in WR_CONSUME. Following this, the 0xD5 error code is forced in
bt_start_transaction, IPMI fails to initialize, and the interface is torn down.
There is no mechanism to retry bringing up the interface in open() /dev/ipmi.
This leaves IPMI hosed until you reload modules. Looks to happen after we call
schedule().
The problem is intermittent, but we observe ~50% fail rate on 4.18
kernels on our UV4 systems.
Here's the relevant snippet (the action starts at 120.367379):
[ 118.316764] IPMI System Interface driver.
[ 118.354246] ipmi_si dmi-ipmi-si.0: ipmi_platform: probing via SMBIOS
[ 118.354249] ipmi_si: SMBIOS: mem 0xce4 regsize 1 spacing 1 irq 6
[ 118.354251] ipmi_si: Adding SMBIOS-specified bt state machine
[ 118.354311] ipmi_si IPI0001:00: ipmi_platform: probing via ACPI
[ 118.381164] ipmi_si IPI0001:00: [io 0x0ce4-0x0ce6] regsize 1 spacing 1 irq 6
[ 118.381167] ipmi_si: Adding ACPI-specified bt state machine
[ 118.382811] ipmi_si: Trying SMBIOS-specified bt state machine at mem address 0xce4, slave address 0x20, irq 6
[ 118.382815] ipmi_si dmi-ipmi-si.0: Could not set up I/O space
[ 118.382816] ipmi_si: Trying ACPI-specified bt state machine at i/o address 0xce4, slave address 0x0, irq 6
[ 118.382911] IPMI BT: flag reset [ ]
[ 118.383008] BT: XACTION [ ] TO=5000000 - 0
[ 118.383059] BT: WR_BYTES [ ] TO=5000000 - 0
[ 118.383272] BT: WR_CONSUME [ H2B ] TO=5000000 - 0
[ 118.388034] BT: WR_CONSUME [ ] TO=5000000 - 4000
[ 118.388059] BT: RD_WAIT [ ] TO=4996000 - 0
[ 118.396017] BT: RD_WAIT [ ] TO=4996000 - 4000
[ 118.492015] BT: RD_WAIT [ ] TO=4992000 - 4000
[ 118.520073] BT: RD_WAIT [ ] TO=4988000 - 4000
[ 118.528079] BT: RD_WAIT [ ] TO=4984000 - 4000
[ 118.540049] BT: RD_WAIT [ ] TO=4980000 - 4000
[ 118.548011] BT: RD_WAIT [ ] TO=4976000 - 4000
[ 118.564033] BT: RD_WAIT [ ] TO=4972000 - 4000
[ 118.572109] BT: RD_WAIT [ ] TO=4968000 - 4000
[ 118.580013] BT: RD_WAIT [ ] TO=4964000 - 4000
[ 118.588017] BT: RD_WAIT [ ] TO=4960000 - 4000
[ 118.608014] BT: RD_WAIT [ ] TO=4956000 - 4000
[ 118.628058] BT: RD_WAIT [ ] TO=4952000 - 4000
[ 118.636053] BT: RD_WAIT [ ] TO=4948000 - 4000
[ 118.648016] BT: RD_WAIT [ ] TO=4944000 - 4000
[ 118.672028] BT: RD_WAIT [ ] TO=4940000 - 4000
[ 118.684056] BT: RD_WAIT [ ] TO=4936000 - 4000
[ 118.696021] BT: RD_WAIT [ ] TO=4932000 - 4000
[ 118.708015] BT: RD_WAIT [ ] TO=4928000 - 4000
[ 118.720018] BT: RD_WAIT [ ] TO=4924000 - 4000
[ 118.732063] BT: RD_WAIT [ ] TO=4920000 - 4000
[ 118.744021] BT: RD_WAIT [ ] TO=4916000 - 4000
[ 118.752089] BT: RD_WAIT [ ] TO=4912000 - 4000
[ 118.764011] BT: RD_WAIT [ ] TO=4908000 - 4000
[ 118.784009] BT: RD_WAIT [ ] TO=4904000 - 4000
[ 118.808011] BT: RD_WAIT [ ] TO=4900000 - 4000
[ 118.832010] BT: RD_WAIT [ ] TO=4896000 - 4000
[ 118.844011] BT: RD_WAIT [ ] TO=4892000 - 4000
[ 118.860036] BT: RD_WAIT [ ] TO=4888000 - 4000
[ 118.868102] BT: RD_WAIT [ ] TO=4884000 - 4000
[ 118.876012] BT: RD_WAIT [ ] TO=4880000 - 4000
[ 118.904011] BT: RD_WAIT [ ] TO=4876000 - 4000
[ 118.924013] BT: RD_WAIT [ ] TO=4872000 - 4000
[ 118.948016] BT: RD_WAIT [ ] TO=4868000 - 4000
[ 118.984043] BT: RD_WAIT [ ] TO=4864000 - 4000
[ 118.992059] BT: RD_WAIT [ ] TO=4860000 - 4000
[ 118.995422] for 2000000
[ 118.995650]
[ 119.000026] BT: RD_WAIT [ ] TO=4856000 - 4000
[ 119.012018] BT: RD_WAIT [ ] TO=4852000 - 4000
[ 119.032010] BT: RD_WAIT [ ] TO=4848000 - 4000
[ 119.048013] BT: RD_WAIT [ ] TO=4844000 - 4000
[ 119.060013] BT: RD_WAIT [ ] TO=4840000 - 4000
[ 119.080014] BT: RD_WAIT [ ] TO=4836000 - 4000
[ 119.096021] BT: RD_WAIT [ ] TO=4832000 - 4000
[ 119.120009] BT: RD_WAIT [ ] TO=4828000 - 4000
[ 119.128017] BT: RD_WAIT [ ] TO=4824000 - 4000
[ 119.136011] BT: RD_WAIT [ ] TO=4820000 - 4000
[ 119.144013] BT: RD_WAIT [ ] TO=4816000 - 4000
[ 119.164008] BT: RD_WAIT [ ] TO=4812000 - 4000
[ 119.184010] BT: RD_WAIT [ ] TO=4808000 - 4000
[ 119.204015] BT: RD_WAIT [ ] TO=4804000 - 4000
[ 119.264034] BT: RD_WAIT [ ] TO=4800000 - 4000
[ 119.272013] BT: RD_WAIT [ ] TO=4796000 - 4000
[ 119.288013] BT: RD_WAIT [ ] TO=4792000 - 4000
[ 119.308011] BT: RD_WAIT [ ] TO=4788000 - 4000
[ 119.324011] BT: RD_WAIT [ ] TO=4784000 - 4000
[ 119.344010] BT: RD_WAIT [ ] TO=4780000 - 4000
[ 119.364027] BT: RD_WAIT [ ] TO=4776000 - 4000
[ 119.376011] BT: RD_WAIT [ ] TO=4772000 - 4000
[ 119.396010] BT: RD_WAIT [ ] TO=4768000 - 4000
[ 119.408013] BT: RD_WAIT [ ] TO=4764000 - 4000
[ 119.424012] BT: RD_WAIT [ B2H ] TO=4760000 - 4000
[ 119.434845] BT: CLEAR_B2H [ H_BUSY ] TO=4756000 - 0
[ 119.592204] BT: RD_BYTES [ H_BUSY ] TO=4756000 - 0
[ 119.650481] BT: XACTION [ ] TO=5000000 - 0
[ 119.676062] BT: WR_BYTES [ ] TO=5000000 - 0
[ 119.734596] BT: WR_CONSUME [ H2B ] TO=5000000 - 0
[ 119.740019] BT: WR_CONSUME [ ] TO=5000000 - 4000
[ 119.740036] BT: RD_WAIT [ ] TO=4996000 - 0
[ 119.748032] BT: RD_WAIT [ B2H ] TO=4996000 - 4000
[ 119.748101] BT: CLEAR_B2H [ H_BUSY ] TO=4992000 - 0
[ 119.748124] BT: RD_BYTES [ H_BUSY ] TO=4992000 - 0
[ 119.748348] BT: XACTION [ ] TO=5000000 - 0
[ 119.748382] BT: WR_BYTES [ ] TO=5000000 - 0
[ 119.748537] BT: WR_CONSUME [ H2B ] TO=5000000 - 0
[ 119.760013] BT: WR_CONSUME [ B2H ] TO=5000000 - 4000
[ 119.806271] BT: RD_WAIT [ B2H ] TO=4996000 - 0
[ 119.806282] BT: CLEAR_B2H [ H_BUSY ] TO=4996000 - 0
[ 119.816909] BT: RD_BYTES [ H_BUSY ] TO=4996000 - 0
[ 119.816944] BT: XACTION [ ] TO=5000000 - 0
[ 119.827061] BT: WR_BYTES [ ] TO=5000000 - 0
[ 119.827088] BT: WR_CONSUME [ H2B ] TO=5000000 - 0
[ 119.852024] BT: WR_CONSUME [ B2H ] TO=5000000 - 4000
[ 119.875752] BT: RD_WAIT [ B2H ] TO=4996000 - 0
[ 119.895099] BT: CLEAR_B2H [ H_BUSY ] TO=4996000 - 0
[ 119.991768] BT: RD_BYTES [ H_BUSY ] TO=4996000 - 0
[ 119.991805] BT: XACTION [ ] TO=5000000 - 0
[ 120.004993] BT: WR_BYTES [ ] TO=5000000 - 0
[ 120.027171] BT: WR_CONSUME [ H2B ] TO=5000000 - 0
[ 120.048024] BT: WR_CONSUME [ ] TO=5000000 - 4000
[ 120.072949] BT: RD_WAIT [ B2H ] TO=4996000 - 0
[ 120.085892] BT: CLEAR_B2H [ H_BUSY ] TO=4996000 - 0
[ 120.097374] BT: RD_BYTES [ H_BUSY ] TO=4996000 - 0
[ 120.097406] BT: XACTION [ ] TO=5000000 - 0
[ 120.125568] BT: WR_BYTES [ ] TO=5000000 - 0
[ 120.141827] BT: WR_CONSUME [ H2B ] TO=5000000 - 0
[ 120.264026] BT: WR_CONSUME [ B2H ] TO=5000000 - 4000
[ 120.287267] BT: RD_WAIT [ B2H ] TO=4996000 - 0
[ 120.287276] BT: CLEAR_B2H [ H_BUSY ] TO=4996000 - 0
[ 120.287280] BT: RD_BYTES [ H_BUSY ] TO=4996000 - 0
[ 120.287429] ipmi_si IPI0001:00: Using irq 6
[ 120.287447] **Interrupt: 1534434704.287445059
[ 120.287457] BT: XACTION [ ] TO=5000000 - 0
[ 120.287466] BT: WR_BYTES [ ] TO=5000000 - 0
[ 120.287500] BT: WR_CONSUME [ H2B ] TO=5000000 - 0
[ 120.297445] **Interrupt: 1534434704.297445691
[ 120.332534] BT: WR_CONSUME [ B2H ] TO=5000000 - 0
[ 120.332538] BT: RD_WAIT [ B2H ] TO=5000000 - 0
[ 120.342956] BT: CLEAR_B2H [ H_BUSY ] TO=5000000 - 0
[ 120.342969] BT: RD_BYTES [ H_BUSY ] TO=5000000 - 0
[ 120.343244] **Done: 1534434704.343244675
[ 120.367379] BT: IDLE [ ] TO=5000000 - 0
[ 120.367384] BT: CAP_BEGIN [ ] TO=5000000 - 0
[ 120.376634] **Timer: 1534434704.376633453
[ 120.376646] BT: XACTION [ ] TO=5000000 - 92000
[ 120.376683] BT: WR_BYTES [ ] TO=4908000 - 0
[ 120.376995] BT: WR_CONSUME [ H2B ] TO=4908000 - 0
[ 120.377025] Send: 18 08
[ 120.377027] **Enqueue: 1534434704.377028726
[ 120.377028] **Start2: 1534434704.377029859
[ 120.377061] BT: WR_CONSUME [ ] TO=4908000 - 0
[ 120.377137] BT: RD_WAIT [ ] TO=4908000 - 0
[ 120.377140] Recv:: 1c 08 d5
[ 120.377156] Send: 18 01
[ 120.377161] **Enqueue: 1534434704.377161047
[ 120.377164] **Start2: 1534434704.377164751
[ 120.377226] BT: RD_WAIT [ ] TO=4908000 - 0
[ 120.377237] Recv:: 1c 01 d5
[ 120.377242] ipmi_si IPI0001:00: IPMI message handler: device id demangle failed: -22
[ 120.377252] ipmi_si IPI0001:00: Unable to get the device id: -5
[ 120.377252] ipmi_si IPI0001:00: Unable to register device: error -5
[ 120.569865] IPMI SSIF Interface driver
Also FYI,
Bad cleanup code causes a null pointer and adds a race condition; this
is addressed by "[PATCH] Remove redundant cleanup in ipmi_register_smi"
from Justin Ernst <justin.ernst@....com>, which I paste here:
diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 51832b8a2c62..3b0b50c4f064 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -3395,12 +3395,12 @@ int ipmi_register_smi(const struct ipmi_smi_handlers *handlers,
out:
if (rv) {
- ipmi_bmc_unregister(intf);
- list_del_rcu(&intf->link);
+ /*
+ * ipmi_unregister_smi must be called to clean up after
+ * failure. We unlock the mutex to allow ipmi_unregister_smi
+ * to lock it and perform cleanup.
+ */
mutex_unlock(&ipmi_interfaces_mutex);
- synchronize_srcu(&ipmi_interfaces_srcu);
- cleanup_srcu_struct(&intf->users_srcu);
- kref_put(&intf->refcount, intf_free);
} else {
/*
* Keep memory order straight for RCU readers. Make
--
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