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Commit eaa70773 authored by Stephane Eranian's avatar Stephane Eranian Committed by Linus Torvalds
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[PATCH] i386: add smp_call_function_single 



Continiung the series of small patches necessary for the perfmon subsystem,
here is a patch that adds support for the smp_call_function_single()
function for i386.  It exists for almost all other architectures but i386.
The perfmon subsystem needs it in one case to free some state on a
designated remote CPU.

Signed-off-by: default avatarStephane Eranian <eranian@hpl.hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 27d26666

arch/i386/kernel/smp.c

+66 −0
Original line number Diff line number Diff line
@@ -634,3 +634,69 @@ fastcall void smp_call_function_interrupt(struct pt_regs *regs) 
	}

}



/*

 * this function sends a 'generic call function' IPI to one other CPU

 * in the system.

 *

 * cpu is a standard Linux logical CPU number.

 */

static void

__smp_call_function_single(int cpu, void (*func) (void *info), void *info,

				int nonatomic, int wait)

{

	struct call_data_struct data;

	int cpus = 1;



	data.func = func;

	data.info = info;

	atomic_set(&data.started, 0);

	data.wait = wait;

	if (wait)

		atomic_set(&data.finished, 0);



	call_data = &data;

	wmb();

	/* Send a message to all other CPUs and wait for them to respond */

	send_IPI_mask(cpumask_of_cpu(cpu), CALL_FUNCTION_VECTOR);



	/* Wait for response */

	while (atomic_read(&data.started) != cpus)

		cpu_relax();



	if (!wait)

		return;



	while (atomic_read(&data.finished) != cpus)

		cpu_relax();

}



/*

 * smp_call_function_single - Run a function on another CPU

 * @func: The function to run. This must be fast and non-blocking.

 * @info: An arbitrary pointer to pass to the function.

 * @nonatomic: Currently unused.

 * @wait: If true, wait until function has completed on other CPUs.

 *

 * Retrurns 0 on success, else a negative status code.

 *

 * Does not return until the remote CPU is nearly ready to execute <func>

 * or is or has executed.

 */



int smp_call_function_single (int cpu, void (*func) (void *info), void *info,

	int nonatomic, int wait)

{

	/* prevent preemption and reschedule on another processor */

	int me = get_cpu();

	if (cpu == me) {

		WARN_ON(1);

		put_cpu();

		return -EBUSY;

	}

	spin_lock_bh(&call_lock);

	__smp_call_function_single(cpu, func, info, nonatomic, wait);

	spin_unlock_bh(&call_lock);

	put_cpu();

	return 0;

}

EXPORT_SYMBOL(smp_call_function_single);