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Subject[PATCH v6 6/6] hwmon: use smp_call_on_cpu() for dell-smm i8k
Date
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: Juergen Gross <jgross@suse.com>
---
V4: add call to get_online_cpus()
---
drivers/hwmon/dell-smm-hwmon.c | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
index acf9c03..34704b0 100644
--- a/drivers/hwmon/dell-smm-hwmon.c
+++ b/drivers/hwmon/dell-smm-hwmon.c
@@ -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);
@@ -232,6 +222,20 @@ out:
}

/*
+ * 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.
*/
static int i8k_get_fan_status(int fan)
--
2.6.6
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