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Subject[PATCH v5 1/2] x86/platform/intel/iosf_mbi: Add unlocked PMIC bus access notifier unregister
Date
For race free unregistration drivers may need to acquire PMIC bus access
through iosf_mbi_punit_acquire() and then (un)register the notifier without
dropping the lock.

This commit adds an unlocked variant of
iosf_mbi_unregister_pmic_bus_access_notifier for this use case.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
arch/x86/include/asm/iosf_mbi.h | 25 +++++++++++++++++++++++++
arch/x86/platform/intel/iosf_mbi.c | 19 +++++++++++++++++--
2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/iosf_mbi.h b/arch/x86/include/asm/iosf_mbi.h
index c313cac36f56..eb959cd77994 100644
--- a/arch/x86/include/asm/iosf_mbi.h
+++ b/arch/x86/include/asm/iosf_mbi.h
@@ -145,6 +145,18 @@ int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb);
*/
int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb);

+/**
+ * iosf_mbi_unregister_pmic_bus_access_notifier_unlocked - Unregister PMIC bus
+ * notifier, unlocked
+ *
+ * Like iosf_mbi_unregister_pmic_bus_access_notifier(), but for use when the
+ * caller has already called iosf_mbi_punit_acquire() itself.
+ *
+ * @nb: notifier_block to unregister
+ */
+int iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(
+ struct notifier_block *nb);
+
/**
* iosf_mbi_call_pmic_bus_access_notifier_chain - Call PMIC bus notifier chain
*
@@ -153,6 +165,11 @@ int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb);
*/
int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v);

+/**
+ * iosf_mbi_assert_punit_acquired - Assert that the P-Unit has been acquired.
+ */
+void iosf_mbi_assert_punit_acquired(void);
+
#else /* CONFIG_IOSF_MBI is not enabled */
static inline
bool iosf_mbi_available(void)
@@ -196,12 +213,20 @@ int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb)
return 0;
}

+static inline int
+iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(struct notifier_block *nb)
+{
+ return 0;
+}
+
static inline
int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v)
{
return 0;
}

+static inline void iosf_mbi_assert_punit_acquired(void) {}
+
#endif /* CONFIG_IOSF_MBI */

#endif /* IOSF_MBI_SYMS_H */
diff --git a/arch/x86/platform/intel/iosf_mbi.c b/arch/x86/platform/intel/iosf_mbi.c
index a952ac199741..6f37a2137a79 100644
--- a/arch/x86/platform/intel/iosf_mbi.c
+++ b/arch/x86/platform/intel/iosf_mbi.c
@@ -218,14 +218,23 @@ int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb)
}
EXPORT_SYMBOL(iosf_mbi_register_pmic_bus_access_notifier);

+int iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(
+ struct notifier_block *nb)
+{
+ iosf_mbi_assert_punit_acquired();
+
+ return blocking_notifier_chain_unregister(
+ &iosf_mbi_pmic_bus_access_notifier, nb);
+}
+EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier_unlocked);
+
int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb)
{
int ret;

/* Wait for the bus to go inactive before unregistering */
mutex_lock(&iosf_mbi_punit_mutex);
- ret = blocking_notifier_chain_unregister(
- &iosf_mbi_pmic_bus_access_notifier, nb);
+ ret = iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(nb);
mutex_unlock(&iosf_mbi_punit_mutex);

return ret;
@@ -239,6 +248,12 @@ int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v)
}
EXPORT_SYMBOL(iosf_mbi_call_pmic_bus_access_notifier_chain);

+void iosf_mbi_assert_punit_acquired(void)
+{
+ WARN_ON(!mutex_is_locked(&iosf_mbi_punit_mutex));
+}
+EXPORT_SYMBOL(iosf_mbi_assert_punit_acquired);
+
#ifdef CONFIG_IOSF_MBI_DEBUG
static u32 dbg_mdr;
static u32 dbg_mcr;
--
2.14.2
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