Convert pwrdm_mutex to pwrdm_rwsem to avoid trying to relock mutex in the
event that the pwrdm_for_each() callback function calls something that
triggers a pwrdm_lookup(). Problem found by Jouni Högander
<jouni.hogander@xxxxxxxxx>
Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
---
arch/arm/mach-omap2/powerdomain.c | 69 ++++++++++++++++++++-----------------
1 files changed, 37 insertions(+), 32 deletions(-)
diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
index dd9f40e..e1cfbbb 100644
--- a/arch/arm/mach-omap2/powerdomain.c
+++ b/arch/arm/mach-omap2/powerdomain.c
@@ -18,7 +18,7 @@
#include <linux/module.h>
#include <linux/types.h>
#include <linux/delay.h>
-#include <linux/mutex.h>
+#include <linux/rwsem.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/err.h>
@@ -37,8 +37,12 @@
/* pwrdm_list contains all registered struct powerdomains */
static LIST_HEAD(pwrdm_list);
-/* pwrdm_mutex protects pwrdm_list add and del ops */
-static DEFINE_MUTEX(pwrdm_mutex);
+/*
+ * pwrdm_rwsem protects pwrdm_list add and del ops - also reused to
+ * protect pwrdm_clkdms[] during clkdm add/del ops
+ */
+static DECLARE_RWSEM(pwrdm_rwsem);
+
/* Private functions */
@@ -135,7 +139,7 @@ int pwrdm_register(struct powerdomain *pwrdm)
if (!omap_chip_is(pwrdm->omap_chip))
return -EINVAL;
- mutex_lock(&pwrdm_mutex);
+ down_write(&pwrdm_rwsem);
if (_pwrdm_lookup(pwrdm->name)) {
ret = -EEXIST;
goto pr_unlock;
@@ -147,7 +151,7 @@ int pwrdm_register(struct powerdomain *pwrdm)
ret = 0;
pr_unlock:
- mutex_unlock(&pwrdm_mutex);
+ up_write(&pwrdm_rwsem);
return ret;
}
@@ -164,9 +168,9 @@ int pwrdm_unregister(struct powerdomain *pwrdm)
if (!pwrdm)
return -EINVAL;
- mutex_lock(&pwrdm_mutex);
+ down_write(&pwrdm_rwsem);
list_del(&pwrdm->node);
- mutex_unlock(&pwrdm_mutex);
+ up_write(&pwrdm_rwsem);
pr_debug("powerdomain: unregistered %s\n", pwrdm->name);
@@ -187,9 +191,9 @@ struct powerdomain *pwrdm_lookup(const char *name)
if (!name)
return NULL;
- mutex_lock(&pwrdm_mutex);
+ down_read(&pwrdm_rwsem);
pwrdm = _pwrdm_lookup(name);
- mutex_unlock(&pwrdm_mutex);
+ up_read(&pwrdm_rwsem);
return pwrdm;
}
@@ -198,15 +202,15 @@ struct powerdomain *pwrdm_lookup(const char *name)
* pwrdm_for_each - call function on each registered clockdomain
* @fn: callback function *
*
- * Call the supplied function for each registered powerdomain.
- * The callback function can return anything but 0 to bail
- * out early from the iterator. The callback function is called with
- * the pwrdm_mutex held, so no powerdomain structure manipulation
+ * Call the supplied function for each registered powerdomain. The
+ * callback function can return anything but 0 to bail out early from
+ * the iterator. The callback function is called with the pwrdm_rwsem
+ * held for reading, so no powerdomain structure manipulation
* functions should be called from the callback, although hardware
* powerdomain control functions are fine. Returns the last return
* value of the callback function, which should be 0 for success or
- * anything else to indicate failure; or -EINVAL if the function pointer
- * is null.
+ * anything else to indicate failure; or -EINVAL if the function
+ * pointer is null.
*/
int pwrdm_for_each(int (*fn)(struct powerdomain *pwrdm))
{
@@ -216,13 +220,13 @@ int pwrdm_for_each(int (*fn)(struct powerdomain *pwrdm))
if (!fn)
return -EINVAL;
- mutex_lock(&pwrdm_mutex);
+ down_read(&pwrdm_rwsem);
list_for_each_entry(temp_pwrdm, &pwrdm_list, node) {
ret = (*fn)(temp_pwrdm);
if (ret)
break;
}
- mutex_unlock(&pwrdm_mutex);
+ up_read(&pwrdm_rwsem);
return ret;
}
@@ -247,7 +251,8 @@ int pwrdm_add_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
pr_debug("powerdomain: associating clockdomain %s with powerdomain "
"%s\n", clkdm->name, pwrdm->name);
- mutex_lock(&pwrdm_mutex);
+
+ down_write(&pwrdm_rwsem);
for (i = 0; i < PWRDM_MAX_CLKDMS; i++) {
if (!pwrdm->pwrdm_clkdms[i])
@@ -273,13 +278,13 @@ int pwrdm_add_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
ret = 0;
pac_exit:
- mutex_unlock(&pwrdm_mutex);
+ up_write(&pwrdm_rwsem);
return ret;
}
/**
- * pwrdm_del_clkdm - remove a clockdomain to a powerdomain
+ * pwrdm_del_clkdm - remove a clockdomain from a powerdomain
* @pwrdm: struct powerdomain * to add the clockdomain to
* @clkdm: struct clockdomain * to associate with a powerdomain
*
@@ -299,25 +304,25 @@ int pwrdm_del_clkdm(struct powerdomain *pwrdm, struct clockdomain *clkdm)
pr_debug("powerdomain: dissociating clockdomain %s from powerdomain "
"%s\n", clkdm->name, pwrdm->name);
- mutex_lock(&pwrdm_mutex);
-
+ down_write(&pwrdm_rwsem);
+
for (i = 0; i < PWRDM_MAX_CLKDMS; i++)
if (pwrdm->pwrdm_clkdms[i] == clkdm)
break;
-
+
if (i == PWRDM_MAX_CLKDMS) {
pr_debug("powerdomain: clkdm %s not associated with pwrdm "
"%s ?!\n", clkdm->name, pwrdm->name);
ret = -ENOENT;
goto pdc_exit;
}
-
+
pwrdm->pwrdm_clkdms[i] = NULL;
-
+
ret = 0;
pdc_exit:
- mutex_unlock(&pwrdm_mutex);
+ up_write(&pwrdm_rwsem);
return ret;
}
@@ -330,10 +335,10 @@ pdc_exit:
* Call the supplied function for each clockdomain in the powerdomain
* 'pwrdm'. The callback function can return anything but 0 to bail
* out early from the iterator. The callback function is called with
- * the pwrdm_mutex held, so no powerdomain structure manipulation
- * functions should be called from the callback, although hardware
- * powerdomain control functions are fine. Returns -EINVAL if
- * presented with invalid pointers; or passes along the last return
+ * the pwrdm_rwsem held for reading, so no powerdomain structure
+ * manipulation functions should be called from the callback, although
+ * hardware powerdomain control functions are fine. Returns -EINVAL
+ * if presented with invalid pointers; or passes along the last return
* value of the callback function, which should be 0 for success or
* anything else to indicate failure.
*/
@@ -347,12 +352,12 @@ int pwrdm_for_each_clkdm(struct powerdomain *pwrdm,
if (!fn)
return -EINVAL;
- mutex_lock(&pwrdm_mutex);
+ down_read(&pwrdm_rwsem);
for (i = 0; i < PWRDM_MAX_CLKDMS && !ret; i++)
ret = (*fn)(pwrdm, pwrdm->pwrdm_clkdms[i]);
- mutex_unlock(&pwrdm_mutex);
+ up_read(&pwrdm_rwsem);
return ret;
}
