[RFC 8/8] PM / Domains: Add asserts for PM domain locks

Krzysztof Kozlowski
2017-06-09T16:09:33Z

Add lockdep checks for holding domain lock in few places where this is
required. This might expose misuse even though only file-scope
functions use it for now.

Regular lockdep asserts can be entirely discarded by preprocessor, however
domain code uses mixed type of lock: spinlock or mutex. This means that
these asserts will not be thrown away entirely. Instead, always
at least two pointer dereferences (p->lock_ops->assert_held) and
probably one function call (assert_held()) will be made.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
---
drivers/base/power/domain.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index c1e22b613287..17fecfd44607 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -40,12 +40,18 @@ static LIST_HEAD(gpd_list);
static DEFINE_MUTEX(gpd_list_lock);

struct genpd_lock_ops {
+ void (*assert_held)(struct generic_pm_domain *genpd);
void (*lock)(struct generic_pm_domain *genpd);
void (*lock_nested)(struct generic_pm_domain *genpd, int depth);
int (*lock_interruptible)(struct generic_pm_domain *genpd);
void (*unlock)(struct generic_pm_domain *genpd);
};

+static void genpd_assert_held_mtx(struct generic_pm_domain *genpd)
+{
+ lockdep_assert_held(&genpd->mlock);
+}
+
static void genpd_lock_mtx(struct generic_pm_domain *genpd)
{
mutex_lock(&genpd->mlock);
@@ -68,12 +74,18 @@ static void genpd_unlock_mtx(struct generic_pm_domain *genpd)
}

static const struct genpd_lock_ops genpd_mtx_ops = {
+ .assert_held = genpd_assert_held_mtx,
.lock = genpd_lock_mtx,
.lock_nested = genpd_lock_nested_mtx,
.lock_interruptible = genpd_lock_interruptible_mtx,
.unlock = genpd_unlock_mtx,
};

+static void genpd_assert_held_spin(struct generic_pm_domain *genpd)
+{
+ lockdep_assert_held(&genpd->slock);
+}
+
static void genpd_lock_spin(struct generic_pm_domain *genpd)
__acquires(&genpd->slock)
{
@@ -110,12 +122,14 @@ static void genpd_unlock_spin(struct generic_pm_domain *genpd)
}

static const struct genpd_lock_ops genpd_spin_ops = {
+ .assert_held = genpd_assert_held_spin,
.lock = genpd_lock_spin,
.lock_nested = genpd_lock_nested_spin,
.lock_interruptible = genpd_lock_interruptible_spin,
.unlock = genpd_unlock_spin,
};

+#define genpd_assert_held(p) p->lock_ops->assert_held(p)
#define genpd_lock(p) p->lock_ops->lock(p)
#define genpd_lock_nested(p, d) p->lock_ops->lock_nested(p, d)
#define genpd_lock_interruptible(p) p->lock_ops->lock_interruptible(p)
@@ -299,6 +313,8 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
struct gpd_link *link;
unsigned int not_suspended = 0;

+ genpd_assert_held(genpd);
+
/*
* Do not try to power off the domain in the following situations:
* (1) The domain is already in the "power off" state.
@@ -385,6 +401,8 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
struct gpd_link *link;
int ret = 0;

+ genpd_assert_held(genpd);
+
if (genpd_status_on(genpd))
return 0;

@@ -766,6 +784,9 @@ static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,
{
struct gpd_link *link;

+ if (use_lock)
+ genpd_assert_held(genpd);
+
if (!genpd_status_on(genpd) || genpd_is_always_on(genpd))
return;

@@ -808,6 +829,9 @@ static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
{
struct gpd_link *link;

+ if (use_lock)
+ genpd_assert_held(genpd);
+
if (genpd_status_on(genpd))
return;

--
2.9.3