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Message-Id: <20090611225929.2A113DDDA2@ozlabs.org>
Date: Thu, 11 Jun 2009 22:59:58 +0930
From: Rusty Russell <rusty@...tcorp.com.au>
To: linux-kernel@...r.kernel.org
Cc: Len Brown <lenb@...nel.org>
Subject: [PATCH 5/6] acpi: don't play with current's cpumask in drivers/acpi/processor_throttling.c
It's generally a very bad idea to mug some process's cpumask: it could
legitimately and reasonably be changed by root, which could break us
(if done before our code) or them (if we restore the wrong value).
So we use smp_call_function_single in two places instead of cpumask games.
If this code isn't interrupt safe, it will now break.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Cc: Len Brown <lenb@...nel.org>
---
drivers/acpi/processor_throttling.c | 82 ++++++++++++++++++------------------
1 file changed, 43 insertions(+), 39 deletions(-)
diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -852,10 +852,21 @@ static int acpi_processor_get_throttling
return 0;
}
+struct get_throttling {
+ struct acpi_processor *pr;
+ int ret;
+};
+
+static void get_throttling(void *_gt)
+{
+ struct get_throttling *gt = _gt;
+
+ gt->ret = gt->pr->throttling.acpi_processor_get_throttling(gt->pr);
+}
+
static int acpi_processor_get_throttling(struct acpi_processor *pr)
{
- cpumask_var_t saved_mask;
- int ret;
+ struct get_throttling gt;
if (!pr)
return -EINVAL;
@@ -863,21 +874,9 @@ static int acpi_processor_get_throttling
if (!pr->flags.throttling)
return -ENODEV;
- if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
- return -ENOMEM;
-
- /*
- * Migrate task to the cpu pointed by pr.
- */
- cpumask_copy(saved_mask, ¤t->cpus_allowed);
- /* FIXME: use work_on_cpu() */
- set_cpus_allowed_ptr(current, cpumask_of(pr->id));
- ret = pr->throttling.acpi_processor_get_throttling(pr);
- /* restore the previous state */
- set_cpus_allowed_ptr(current, saved_mask);
- free_cpumask_var(saved_mask);
-
- return ret;
+ gt.pr = pr;
+ smp_call_function_single(pr->id, get_throttling, >, 1);
+ return gt.ret;
}
static int acpi_processor_get_fadt_info(struct acpi_processor *pr)
@@ -1018,9 +1017,23 @@ static int acpi_processor_set_throttling
return 0;
}
+struct set_throttling_info {
+ struct acpi_processor *pr;
+ struct acpi_processor_throttling *p_throttling;
+ int target_state;
+ int ret;
+};
+
+static void set_throttling(void *_sti)
+{
+ struct set_throttling_info *s = _sti;
+
+ s->ret = s->p_throttling->acpi_processor_set_throttling(s->pr,
+ s->target_state);
+}
+
int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
{
- cpumask_var_t saved_mask;
int ret = 0;
unsigned int i;
struct acpi_processor *match_pr;
@@ -1037,15 +1050,9 @@ int acpi_processor_set_throttling(struct
if ((state < 0) || (state > (pr->throttling.state_count - 1)))
return -EINVAL;
- if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
+ if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL))
return -ENOMEM;
- if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL)) {
- free_cpumask_var(saved_mask);
- return -ENOMEM;
- }
-
- cpumask_copy(saved_mask, ¤t->cpus_allowed);
t_state.target_state = state;
p_throttling = &(pr->throttling);
cpumask_and(online_throttling_cpus, cpu_online_mask,
@@ -1067,10 +1074,10 @@ int acpi_processor_set_throttling(struct
* it can be called only for the cpu pointed by pr.
*/
if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
- /* FIXME: use work_on_cpu() */
- set_cpus_allowed_ptr(current, cpumask_of(pr->id));
- ret = p_throttling->acpi_processor_set_throttling(pr,
- t_state.target_state);
+ struct set_throttling_info sti
+ = { pr, p_throttling, t_state.target_state };
+ smp_call_function_single(pr->id, set_throttling, &sti, 1);
+ ret = sti.ret;
} else {
/*
* When the T-state coordination is SW_ALL or HW_ALL,
@@ -1078,6 +1085,8 @@ int acpi_processor_set_throttling(struct
* cpus.
*/
for_each_cpu(i, online_throttling_cpus) {
+ struct set_throttling_info sti;
+
match_pr = per_cpu(processors, i);
/*
* If the pointer is invalid, we will report the
@@ -1099,11 +1108,11 @@ int acpi_processor_set_throttling(struct
continue;
}
t_state.cpu = i;
- /* FIXME: use work_on_cpu() */
- set_cpus_allowed_ptr(current, cpumask_of(i));
- ret = match_pr->throttling.
- acpi_processor_set_throttling(
- match_pr, t_state.target_state);
+ sti.pr = match_pr;
+ sti.p_throttling = &match_pr->throttling;
+ sti.target_state = t_state.target_state;
+ smp_call_function_single(i, set_throttling, &sti, 1);
+ ret = sti.ret;
}
}
/*
@@ -1117,11 +1126,6 @@ int acpi_processor_set_throttling(struct
acpi_processor_throttling_notifier(THROTTLING_POSTCHANGE,
&t_state);
}
- /* restore the previous state */
- /* FIXME: use work_on_cpu() */
- set_cpus_allowed_ptr(current, saved_mask);
- free_cpumask_var(online_throttling_cpus);
- free_cpumask_var(saved_mask);
return ret;
}
--
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