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Message-ID: <20160405145414.GB27359@roeck-us.net>
Date: Tue, 5 Apr 2016 07:54:14 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Juergen Gross <jgross@...e.com>
Cc: linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
boris.ostrovsky@...cle.com, david.vrabel@...rix.com,
mingo@...hat.com, peterz@...radead.org, Douglas_Warzecha@...l.com,
pali.rohar@...il.com, jdelvare@...e.com, tglx@...utronix.de,
hpa@...or.com, jeremy@...p.org, chrisw@...s-sol.org,
akataria@...are.com, rusty@...tcorp.com.au,
virtualization@...ts.linux-foundation.org, x86@...nel.org
Subject: Re: [PATCH v4 6/6] hwmon: use smp_call_on_cpu() for dell-smm i8k
On Tue, Apr 05, 2016 at 07:10:07AM +0200, Juergen Gross wrote:
> 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@...e.com>
> ---
> V4: add call to get_online_cpus()
Pali, any chance to test this ?
Thanks,
Guenter
> ---
> drivers/hwmon/dell-smm-hwmon.c | 35 ++++++++++++++++++++---------------
> 1 file changed, 20 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
> index c43318d..643f3a1 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>
> @@ -35,6 +36,7 @@
> #include <linux/uaccess.h>
> #include <linux/io.h>
> #include <linux/sched.h>
> +#include <linux/smp.h>
>
> #include <linux/i8k.h>
>
> @@ -130,23 +132,15 @@ 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;
>
> /* SMM requires CPU 0 */
> - if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
> - return -ENOMEM;
> - cpumask_copy(old_mask, ¤t->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"
> @@ -204,13 +198,24 @@ 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);
> 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, true, i8k_smm_func, regs);
> + put_online_cpus();
> +
> + return ret;
> +}
> +
> +/*
> * Read the fan status.
> */
> static int i8k_get_fan_status(int fan)
> --
> 2.6.2
>
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