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Commit 27046a3f authored by Juergen Gross's avatar Juergen Gross Committed by Ingo Molnar
Browse files

hwmon: Use smp_call_on_cpu() for dell-smm i8k 



Use the smp_call_on_cpu() function to call system management
mode on CPU 0.
Make call secure by adding get_online_cpus() to avoid e.g. suspend
resume cycles in between.

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Douglas_Warzecha@dell.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akataria@vmware.com
Cc: boris.ostrovsky@oracle.com
Cc: chrisw@sous-sol.org
Cc: david.vrabel@citrix.com
Cc: hpa@zytor.com
Cc: jdelvare@suse.com
Cc: jeremy@goop.org
Cc: linux@roeck-us.net
Cc: pali.rohar@gmail.com
Cc: rusty@rustcorp.com.au
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1472453327-19050-7-git-send-email-jgross@suse.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e23f22b5

drivers/hwmon/dell-smm-hwmon.c

+20 −16
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <linux/cpu.h>

#include <linux/delay.h>

#include <linux/module.h>

#include <linux/types.h>
@@ -36,6 +37,7 @@ 
#include <linux/io.h>

#include <linux/sched.h>

#include <linux/ctype.h>

#include <linux/smp.h>



#include <linux/i8k.h>
@@ -134,11 +136,11 @@ static inline const char *i8k_get_dmi_data(int field) 
/*

 * Call the System Management Mode BIOS. Code provided by Jonathan Buzzard.

 */

static int i8k_smm(struct smm_regs *regs)

static int i8k_smm_func(void *par)

{

	int rc;

	struct smm_regs *regs = par;

	int eax = regs->eax;

	cpumask_var_t old_mask;



#ifdef DEBUG

	int ebx = regs->ebx;
@@ -149,16 +151,8 @@ static int i8k_smm(struct smm_regs *regs) 
#endif



	/* SMM requires CPU 0 */

	if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))

		return -ENOMEM;

	cpumask_copy(old_mask, &current->cpus_allowed);

	rc = set_cpus_allowed_ptr(current, cpumask_of(0));

	if (rc)

		goto out;

	if (smp_processor_id() != 0) {

		rc = -EBUSY;

		goto out;

	}

	if (smp_processor_id() != 0)

		return -EBUSY;



#if defined(CONFIG_X86_64)

	asm volatile("pushq %%rax\n\t"
@@ -216,10 +210,6 @@ static int i8k_smm(struct smm_regs *regs) 
	if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)

		rc = -EINVAL;



out:

	set_cpus_allowed_ptr(current, old_mask);

	free_cpumask_var(old_mask);



#ifdef DEBUG

	rettime = ktime_get();

	delta = ktime_sub(rettime, calltime);
@@ -231,6 +221,20 @@ static int i8k_smm(struct smm_regs *regs) 
	return rc;

}



/*

 * Call the System Management Mode BIOS.

 */

static int i8k_smm(struct smm_regs *regs)

{

	int ret;



	get_online_cpus();

	ret = smp_call_on_cpu(0, i8k_smm_func, regs, true);

	put_online_cpus();



	return ret;

}



/*

 * Read the fan status.

 */