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Message-Id: <1378130298-23681-1-git-send-email-tcamuso@redhat.com>
Date: Mon, 2 Sep 2013 11:00:53 -0400
From: Tony Camuso <tcamuso@...hat.com>
To: linux-kernel@...r.kernel.org, minyard@....org,
devicetree-discuss@...ts.ozlabs.org, tcamuso@...hat.com
Cc: dzickus@...hat.com
Subject: [PATCH 1/1] drivers/acpi: acpi_ipmi.c replace mutex with spin_lock_irqsave
From: tcamuso@...hat.com
From: Tony Camuso <tcamuso@...hat.com>
We were getting occasional "Scheduling while atomic" call traces
during boot on some systems. Problem was first seen on a Cisco C210
but we were able to reproduce it on a Cisco c220m3. Setting
CONFIG_LOCKDEP and LOCKDEP_SUPPORT to 'y' exposed a lockdep around
tx_msg_lock in acpi_ipmi.c struct acpi_ipmi_device.
=================================
[ INFO: inconsistent lock state ]
2.6.32-415.el6.x86_64-debug-splck #1
---------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/3/17 [HC0[0]:SC1[1]:HE1:SE0] takes:
(&ipmi_device->tx_msg_lock){+.?...}, at: [<ffffffff81337a27>] ipmi_msg_handler+0x71/0x126
{SOFTIRQ-ON-W} state was registered at:
[<ffffffff810ba11c>] __lock_acquire+0x63c/0x1570
[<ffffffff810bb0f4>] lock_acquire+0xa4/0x120
[<ffffffff815581cc>] __mutex_lock_common+0x4c/0x400
[<ffffffff815586ea>] mutex_lock_nested+0x4a/0x60
[<ffffffff8133789d>] acpi_ipmi_space_handler+0x11b/0x234
[<ffffffff81321c62>] acpi_ev_address_space_dispatch+0x170/0x1be
The ipmi_msg_handler() function in drivers/acpi/acpi_ipmi was taking
a mutex_lock after ultimately being called from a call chain initiated
by function smi_rcv_tasklet() in drivers/char/ipmi/ipmi_msghandler.c.
Documentation/mutex-design.txt on lines 93 and 94 says, "mutexes may
not be used in hardware or software interrupt contexts such as
tasklets and timers."
The patch changes the mutex member tx_msg_lock in acpi_ipmi.c struct
acpi_ipmi_device to a spinlock_t and replaces mutex_lock/unlock pairs
with spin_lock_irqsave/unlock_irqrestore around tx_msg_lock for
accesses to that struct.
Tested the patch in a boot loop with lockdep debug enabled and never
saw the problem in over 400 reboots.
Signed-off-by: Tony Camuso <tcamuso@...hat.com>
---
drivers/acpi/acpi_ipmi.c | 24 ++++++++++++++----------
1 files changed, 14 insertions(+), 10 deletions(-)
diff --git a/drivers/acpi/acpi_ipmi.c b/drivers/acpi/acpi_ipmi.c
index f40acef..a4b428d 100644
--- a/drivers/acpi/acpi_ipmi.c
+++ b/drivers/acpi/acpi_ipmi.c
@@ -57,7 +57,7 @@ struct acpi_ipmi_device {
struct list_head head;
/* the IPMI request message list */
struct list_head tx_msg_list;
- struct mutex tx_msg_lock;
+ spinlock_t tx_msg_lock;
acpi_handle handle;
struct pnp_dev *pnp_dev;
ipmi_user_t user_interface;
@@ -147,6 +147,7 @@ static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
struct kernel_ipmi_msg *msg;
struct acpi_ipmi_buffer *buffer;
struct acpi_ipmi_device *device;
+ unsigned long flags;
msg = &tx_msg->tx_message;
/*
@@ -177,10 +178,10 @@ static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
/* Get the msgid */
device = tx_msg->device;
- mutex_lock(&device->tx_msg_lock);
+ spin_lock_irqsave(&device->tx_msg_lock, flags);
device->curr_msgid++;
tx_msg->tx_msgid = device->curr_msgid;
- mutex_unlock(&device->tx_msg_lock);
+ spin_unlock_irqrestore(&device->tx_msg_lock, flags);
}
static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
@@ -242,6 +243,7 @@ static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
int msg_found = 0;
struct acpi_ipmi_msg *tx_msg;
struct pnp_dev *pnp_dev = ipmi_device->pnp_dev;
+ unsigned long flags;
if (msg->user != ipmi_device->user_interface) {
dev_warn(&pnp_dev->dev, "Unexpected response is returned. "
@@ -250,7 +252,7 @@ static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
ipmi_free_recv_msg(msg);
return;
}
- mutex_lock(&ipmi_device->tx_msg_lock);
+ spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
list_for_each_entry(tx_msg, &ipmi_device->tx_msg_list, head) {
if (msg->msgid == tx_msg->tx_msgid) {
msg_found = 1;
@@ -258,7 +260,7 @@ static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
}
}
- mutex_unlock(&ipmi_device->tx_msg_lock);
+ spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
if (!msg_found) {
dev_warn(&pnp_dev->dev, "Unexpected response (msg id %ld) is "
"returned.\n", msg->msgid);
@@ -378,6 +380,8 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
struct acpi_ipmi_device *ipmi_device = handler_context;
int err, rem_time;
acpi_status status;
+ unsigned long flags;
+
/*
* IPMI opregion message.
* IPMI message is firstly written to the BMC and system software
@@ -395,9 +399,9 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
return AE_NO_MEMORY;
acpi_format_ipmi_msg(tx_msg, address, value);
- mutex_lock(&ipmi_device->tx_msg_lock);
+ spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
- mutex_unlock(&ipmi_device->tx_msg_lock);
+ spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
err = ipmi_request_settime(ipmi_device->user_interface,
&tx_msg->addr,
tx_msg->tx_msgid,
@@ -413,9 +417,9 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
status = AE_OK;
end_label:
- mutex_lock(&ipmi_device->tx_msg_lock);
+ spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
list_del(&tx_msg->head);
- mutex_unlock(&ipmi_device->tx_msg_lock);
+ spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
kfree(tx_msg);
return status;
}
@@ -457,7 +461,7 @@ static void acpi_add_ipmi_device(struct acpi_ipmi_device *ipmi_device)
INIT_LIST_HEAD(&ipmi_device->head);
- mutex_init(&ipmi_device->tx_msg_lock);
+ spin_lock_init(&ipmi_device->tx_msg_lock);
INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
ipmi_install_space_handler(ipmi_device);
--
1.7.1
--
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