The patch titled
ipmi: don't grab locks in run-to-completion mode
has been added to the -mm tree. Its filename is
ipmi-dont-grab-locks-in-run-to-completion-mode.patch
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See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ipmi: don't grab locks in run-to-completion mode
From: Konstantin Baydarov <kbaidarov@xxxxxxxxxxxxx>
This patch prevents deadlocks in IPMI panic handler caused by msg_lock
in smi_info structure and waiting_msgs_lock in ipmi_smi structure.
Signed-off-by: Konstantin Baydarov <kbaidarov@xxxxxxxxxxxxx>
Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/char/ipmi/ipmi_msghandler.c | 32 +++++++++++++++++++++-----
drivers/char/ipmi/ipmi_si_intf.c | 6 +++-
2 files changed, 30 insertions(+), 8 deletions(-)
diff -puN drivers/char/ipmi/ipmi_msghandler.c~ipmi-dont-grab-locks-in-run-to-completion-mode drivers/char/ipmi/ipmi_msghandler.c
--- a/drivers/char/ipmi/ipmi_msghandler.c~ipmi-dont-grab-locks-in-run-to-completion-mode
+++ a/drivers/char/ipmi/ipmi_msghandler.c
@@ -351,8 +351,16 @@ struct ipmi_smi
/* Invalid data in an event. */
unsigned int invalid_events;
+
/* Events that were received with the proper format. */
unsigned int events;
+
+ /*
+ * run_to_completion duplicate of smb_info, smi_info
+ * and ipmi_serial_info structures. Used to decrease numbers of
+ * parameters passed by "low" level IPMI code.
+ */
+ int run_to_completion;
};
#define to_si_intf_from_dev(device) container_of(device, struct ipmi_smi, dev)
@@ -3451,8 +3459,9 @@ static int handle_new_recv_msg(ipmi_smi_
void ipmi_smi_msg_received(ipmi_smi_t intf,
struct ipmi_smi_msg *msg)
{
- unsigned long flags;
+ unsigned long flags = 0; /* keep us warning-free. */
int rv;
+ int run_to_completion;
if ((msg->data_size >= 2)
@@ -3501,21 +3510,30 @@ void ipmi_smi_msg_received(ipmi_smi_t
/* To preserve message order, if the list is not empty, we
tack this message onto the end of the list. */
- spin_lock_irqsave(&intf->waiting_msgs_lock, flags);
+ run_to_completion = intf->run_to_completion;
+ barrier();
+ if (!run_to_completion)
+ spin_lock_irqsave(&intf->waiting_msgs_lock, flags);
if (!list_empty(&intf->waiting_msgs)) {
list_add_tail(&msg->link, &intf->waiting_msgs);
- spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
+ if (!run_to_completion)
+ spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
goto out;
}
- spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
+ if (!run_to_completion)
+ spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
rv = handle_new_recv_msg(intf, msg);
if (rv > 0) {
/* Could not handle the message now, just add it to a
list to handle later. */
- spin_lock_irqsave(&intf->waiting_msgs_lock, flags);
+ run_to_completion = intf->run_to_completion;
+ barrier();
+ if (!run_to_completion)
+ spin_lock_irqsave(&intf->waiting_msgs_lock, flags);
list_add_tail(&msg->link, &intf->waiting_msgs);
- spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
+ if (!run_to_completion)
+ spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
} else if (rv == 0) {
ipmi_free_smi_msg(msg);
}
@@ -3884,6 +3902,7 @@ static void send_panic_events(char *str)
/* Interface is not ready. */
continue;
+ intf->run_to_completion = 1;
/* Send the event announcing the panic. */
intf->handlers->set_run_to_completion(intf->send_info, 1);
i_ipmi_request(NULL,
@@ -4059,6 +4078,7 @@ static int panic_event(struct notifier_b
/* Interface is not ready. */
continue;
+ intf->run_to_completion = 1;
intf->handlers->set_run_to_completion(intf->send_info, 1);
}
diff -puN drivers/char/ipmi/ipmi_si_intf.c~ipmi-dont-grab-locks-in-run-to-completion-mode drivers/char/ipmi/ipmi_si_intf.c
--- a/drivers/char/ipmi/ipmi_si_intf.c~ipmi-dont-grab-locks-in-run-to-completion-mode
+++ a/drivers/char/ipmi/ipmi_si_intf.c
@@ -289,7 +289,8 @@ static enum si_sm_result start_next_msg(
/* No need to save flags, we aleady have interrupts off and we
already hold the SMI lock. */
- spin_lock(&(smi_info->msg_lock));
+ if (!smi_info->run_to_completion)
+ spin_lock(&(smi_info->msg_lock));
/* Pick the high priority queue first. */
if (!list_empty(&(smi_info->hp_xmit_msgs))) {
@@ -329,7 +330,8 @@ static enum si_sm_result start_next_msg(
rv = SI_SM_CALL_WITHOUT_DELAY;
}
out:
- spin_unlock(&(smi_info->msg_lock));
+ if (!smi_info->run_to_completion)
+ spin_unlock(&(smi_info->msg_lock));
return rv;
}
_
Patches currently in -mm which might be from kbaidarov@xxxxxxxxxxxxx are
ipmi-dont-grab-locks-in-run-to-completion-mode.patch
ipmi-convert-locked-counters-to-atomics.patch
-
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