From: Richard Maina quic_rmaina@quicinc.com
[ Upstream commit 7c327d56597d8de1680cf24e956b704270d3d84a ]
When a remoteproc crashes or goes down unexpectedly this can result in a state where locks held by the remoteproc will remain locked possibly resulting in deadlock. This new API hwspin_lock_bust() allows hwspinlock implementers to define a bust operation for freeing previously acquired hwspinlocks after verifying ownership of the acquired lock.
Signed-off-by: Richard Maina quic_rmaina@quicinc.com Reviewed-by: Bjorn Andersson andersson@kernel.org Signed-off-by: Chris Lew quic_clew@quicinc.com Link: https://lore.kernel.org/r/20240529-hwspinlock-bust-v3-1-c8b924ffa5a2@quicinc... Signed-off-by: Bjorn Andersson andersson@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- Documentation/locking/hwspinlock.rst | 11 ++++++++++ drivers/hwspinlock/hwspinlock_core.c | 28 ++++++++++++++++++++++++ drivers/hwspinlock/hwspinlock_internal.h | 3 +++ include/linux/hwspinlock.h | 6 +++++ 4 files changed, 48 insertions(+)
diff --git a/Documentation/locking/hwspinlock.rst b/Documentation/locking/hwspinlock.rst index 6f03713b70039..2ffaa3cbd63f1 100644 --- a/Documentation/locking/hwspinlock.rst +++ b/Documentation/locking/hwspinlock.rst @@ -85,6 +85,17 @@ is already free).
Should be called from a process context (might sleep).
+:: + + int hwspin_lock_bust(struct hwspinlock *hwlock, unsigned int id); + +After verifying the owner of the hwspinlock, release a previously acquired +hwspinlock; returns 0 on success, or an appropriate error code on failure +(e.g. -EOPNOTSUPP if the bust operation is not defined for the specific +hwspinlock). + +Should be called from a process context (might sleep). + ::
int hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int timeout); diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c index 0c0a932c00f35..6505261e60686 100644 --- a/drivers/hwspinlock/hwspinlock_core.c +++ b/drivers/hwspinlock/hwspinlock_core.c @@ -305,6 +305,34 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags) } EXPORT_SYMBOL_GPL(__hwspin_unlock);
+/** + * hwspin_lock_bust() - bust a specific hwspinlock + * @hwlock: a previously-acquired hwspinlock which we want to bust + * @id: identifier of the remote lock holder, if applicable + * + * This function will bust a hwspinlock that was previously acquired as + * long as the current owner of the lock matches the id given by the caller. + * + * Context: Process context. + * + * Returns: 0 on success, or -EINVAL if the hwspinlock does not exist, or + * the bust operation fails, and -EOPNOTSUPP if the bust operation is not + * defined for the hwspinlock. + */ +int hwspin_lock_bust(struct hwspinlock *hwlock, unsigned int id) +{ + if (WARN_ON(!hwlock)) + return -EINVAL; + + if (!hwlock->bank->ops->bust) { + pr_err("bust operation not defined\n"); + return -EOPNOTSUPP; + } + + return hwlock->bank->ops->bust(hwlock, id); +} +EXPORT_SYMBOL_GPL(hwspin_lock_bust); + /** * of_hwspin_lock_simple_xlate - translate hwlock_spec to return a lock id * @hwlock_spec: hwlock specifier as found in the device tree diff --git a/drivers/hwspinlock/hwspinlock_internal.h b/drivers/hwspinlock/hwspinlock_internal.h index 29892767bb7a0..f298fc0ee5adb 100644 --- a/drivers/hwspinlock/hwspinlock_internal.h +++ b/drivers/hwspinlock/hwspinlock_internal.h @@ -21,6 +21,8 @@ struct hwspinlock_device; * @trylock: make a single attempt to take the lock. returns 0 on * failure and true on success. may _not_ sleep. * @unlock: release the lock. always succeed. may _not_ sleep. + * @bust: optional, platform-specific bust handler, called by hwspinlock + * core to bust a specific lock. * @relax: optional, platform-specific relax handler, called by hwspinlock * core while spinning on a lock, between two successive * invocations of @trylock. may _not_ sleep. @@ -28,6 +30,7 @@ struct hwspinlock_device; struct hwspinlock_ops { int (*trylock)(struct hwspinlock *lock); void (*unlock)(struct hwspinlock *lock); + int (*bust)(struct hwspinlock *lock, unsigned int id); void (*relax)(struct hwspinlock *lock); };
diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h index bfe7c1f1ac6d1..f0231dbc47771 100644 --- a/include/linux/hwspinlock.h +++ b/include/linux/hwspinlock.h @@ -68,6 +68,7 @@ int __hwspin_lock_timeout(struct hwspinlock *, unsigned int, int, int __hwspin_trylock(struct hwspinlock *, int, unsigned long *); void __hwspin_unlock(struct hwspinlock *, int, unsigned long *); int of_hwspin_lock_get_id_byname(struct device_node *np, const char *name); +int hwspin_lock_bust(struct hwspinlock *hwlock, unsigned int id); int devm_hwspin_lock_free(struct device *dev, struct hwspinlock *hwlock); struct hwspinlock *devm_hwspin_lock_request(struct device *dev); struct hwspinlock *devm_hwspin_lock_request_specific(struct device *dev, @@ -127,6 +128,11 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags) { }
+static inline int hwspin_lock_bust(struct hwspinlock *hwlock, unsigned int id) +{ + return 0; +} + static inline int of_hwspin_lock_get_id(struct device_node *np, int index) { return 0;