Commit a9a2c44f authored by Corey Minyard's avatar Corey Minyard Committed by Linus Torvalds
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[PATCH] ipmi: add timer thread 



We must poll for responses to commands when interrupts aren't in use.  The
default poll interval is based on using a kernel timer, which varies with HZ.
For character-based interfaces like KCS and SMIC though, that can be way too
slow (>15 minutes to flash a new firmware with KCS, >20 seconds to retrieve
the sensor list).

This creates a low-priority kernel thread to poll more often.  If the state
machine is idle, so is the kernel thread.  But if there's an active command,
it polls quite rapidly.  This decrease a firmware flash time from 15 minutes
to 1.5 minutes, and the sensor list time to 4.5 seconds, on a Dell PowerEdge
x8x system.

The timer-based polling remains, to ensure some amount of responsiveness even
under high user process CPU load.

Checking for a stopped timer at rmmod now uses atomics and del_timer_sync() to
ensure safe stoppage.

Signed-off-by: default avatarMatt Domsch <Matt_Domsch@dell.com>
Signed-off-by: default avatarCorey Minyard <minyard@acm.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c3e7e791

drivers/char/ipmi/ipmi_si_intf.c

+63 −21
Original line number Diff line number Diff line
@@ -126,6 +126,7 @@ struct ipmi_device_id { 


struct smi_info

{

	int                    intf_num;

	ipmi_smi_t             intf;

	struct si_sm_data      *si_sm;

	struct si_sm_handlers  *handlers;
@@ -193,8 +194,7 @@ struct smi_info 
	unsigned long       last_timeout_jiffies;



	/* Used to gracefully stop the timer without race conditions. */

	volatile int        stop_operation;

	volatile int        timer_stopped;

	atomic_t            stop_operation;



	/* The driver will disable interrupts when it gets into a

	   situation where it cannot handle messages due to lack of
@@ -221,6 +221,9 @@ struct smi_info 
	unsigned long events;

	unsigned long watchdog_pretimeouts;

	unsigned long incoming_messages;



        struct completion exiting;

        long              thread_pid;

};



static struct notifier_block *xaction_notifier_list;
@@ -779,6 +782,38 @@ static void set_run_to_completion(void *send_info, int i_run_to_completion) 
	spin_unlock_irqrestore(&(smi_info->si_lock), flags);

}



static int ipmi_thread(void *data)

{

	struct smi_info *smi_info = data;

	unsigned long flags, last=1;

	enum si_sm_result smi_result;



	daemonize("kipmi%d", smi_info->intf_num);

	allow_signal(SIGKILL);

	set_user_nice(current, 19);

	while (!atomic_read(&smi_info->stop_operation)) {

		schedule_timeout(last);

		spin_lock_irqsave(&(smi_info->si_lock), flags);

		smi_result=smi_event_handler(smi_info, 0);

		spin_unlock_irqrestore(&(smi_info->si_lock), flags);

		if (smi_result == SI_SM_CALL_WITHOUT_DELAY)

			last = 0;

		else if (smi_result == SI_SM_CALL_WITH_DELAY) {

			udelay(1);

			last = 0;

		}

		else {

			/* System is idle; go to sleep */

			last = 1;

			current->state = TASK_INTERRUPTIBLE;

		}

	}

	smi_info->thread_pid = 0;

	complete_and_exit(&(smi_info->exiting), 0);

	return 0;

}





static void poll(void *send_info)

{

	struct smi_info *smi_info = send_info;
@@ -837,10 +872,8 @@ static void smi_timeout(unsigned long data) 
	struct timeval    t;

#endif



	if (smi_info->stop_operation) {

		smi_info->timer_stopped = 1;

	if (atomic_read(&smi_info->stop_operation))

		return;

	}



	spin_lock_irqsave(&(smi_info->si_lock), flags);

#ifdef DEBUG_TIMING
@@ -913,7 +946,7 @@ static irqreturn_t si_irq_handler(int irq, void *data, struct pt_regs *regs) 
	smi_info->interrupts++;

	spin_unlock(&smi_info->count_lock);



	if (smi_info->stop_operation)

	if (atomic_read(&smi_info->stop_operation))

		goto out;



#ifdef DEBUG_TIMING
@@ -1432,7 +1465,7 @@ static u32 ipmi_acpi_gpe(void *context) 
	smi_info->interrupts++;

	spin_unlock(&smi_info->count_lock);



	if (smi_info->stop_operation)

	if (atomic_read(&smi_info->stop_operation))

		goto out;



#ifdef DEBUG_TIMING
@@ -2177,6 +2210,16 @@ static void setup_xaction_handlers(struct smi_info *smi_info) 
	setup_dell_poweredge_bt_xaction_handler(smi_info);

}



static inline void wait_for_timer_and_thread(struct smi_info *smi_info)

{

	if (smi_info->thread_pid > 0) {

		/* wake the potentially sleeping thread */

		kill_proc(smi_info->thread_pid, SIGKILL, 0);

		wait_for_completion(&(smi_info->exiting));

	}

	del_timer_sync(&smi_info->si_timer);

}



/* Returns 0 if initialized, or negative on an error. */

static int init_one_smi(int intf_num, struct smi_info **smi)

{
@@ -2284,8 +2327,8 @@ static int init_one_smi(int intf_num, struct smi_info **smi) 
	new_smi->run_to_completion = 0;



	new_smi->interrupt_disabled = 0;

	new_smi->timer_stopped = 0;

	new_smi->stop_operation = 0;

	atomic_set(&new_smi->stop_operation, 0);

	new_smi->intf_num = intf_num;



	/* Start clearing the flags before we enable interrupts or the

	   timer to avoid racing with the timer. */
@@ -2303,7 +2346,14 @@ static int init_one_smi(int intf_num, struct smi_info **smi) 
	new_smi->si_timer.function = smi_timeout;

	new_smi->last_timeout_jiffies = jiffies;

	new_smi->si_timer.expires = jiffies + SI_TIMEOUT_JIFFIES;



	add_timer(&(new_smi->si_timer));

 	if (new_smi->si_type != SI_BT) {

		init_completion(&(new_smi->exiting));

		new_smi->thread_pid = kernel_thread(ipmi_thread, new_smi,

						    CLONE_FS|CLONE_FILES|

						    CLONE_SIGHAND);

	}



	rv = ipmi_register_smi(&handlers,

			       new_smi,
@@ -2345,12 +2395,8 @@ static int init_one_smi(int intf_num, struct smi_info **smi) 
	return 0;



 out_err_stop_timer:

	new_smi->stop_operation = 1;



	/* Wait for the timer to stop.  This avoids problems with race

	   conditions removing the timer here. */

	while (!new_smi->timer_stopped)

		schedule_timeout_uninterruptible(1);

	atomic_inc(&new_smi->stop_operation);

	wait_for_timer_and_thread(new_smi);



 out_err:

	if (new_smi->intf)
@@ -2456,8 +2502,7 @@ static void __exit cleanup_one_si(struct smi_info *to_clean) 
	spin_lock_irqsave(&(to_clean->si_lock), flags);

	spin_lock(&(to_clean->msg_lock));



	to_clean->stop_operation = 1;



	atomic_inc(&to_clean->stop_operation);

	to_clean->irq_cleanup(to_clean);



	spin_unlock(&(to_clean->msg_lock));
@@ -2468,10 +2513,7 @@ static void __exit cleanup_one_si(struct smi_info *to_clean) 
	   interrupt. */

	synchronize_sched();



	/* Wait for the timer to stop.  This avoids problems with race

	   conditions removing the timer here. */

	while (!to_clean->timer_stopped)

		schedule_timeout_uninterruptible(1);

	wait_for_timer_and_thread(to_clean);



	/* Interrupts and timeouts are stopped, now make sure the

	   interface is in a clean state. */

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