locking/rtmutex: Extend the rtmutex core to support ww_mutex

Add a ww acquire context pointer to the waiter and various functions and
add the ww_mutex related invocations to the proper spots in the locking
code, similar to the mutex based variant.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211304.966139174@linutronix.de

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index ac8fb2f..af7e3af 100644 (file)
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -17,9 +17,44 @@
 #include <linux/sched/signal.h>
 #include <linux/sched/rt.h>
 #include <linux/sched/wake_q.h>
+#include <linux/ww_mutex.h>
 
 #include "rtmutex_common.h"
 
+#ifndef WW_RT
+# define build_ww_mutex()      (false)
+# define ww_container_of(rtm)  NULL
+
+static inline int __ww_mutex_add_waiter(struct rt_mutex_waiter *waiter,
+                                       struct rt_mutex *lock,
+                                       struct ww_acquire_ctx *ww_ctx)
+{
+       return 0;
+}
+
+static inline void __ww_mutex_check_waiters(struct rt_mutex *lock,
+                                           struct ww_acquire_ctx *ww_ctx)
+{
+}
+
+static inline void ww_mutex_lock_acquired(struct ww_mutex *lock,
+                                         struct ww_acquire_ctx *ww_ctx)
+{
+}
+
+static inline int __ww_mutex_check_kill(struct rt_mutex *lock,
+                                       struct rt_mutex_waiter *waiter,
+                                       struct ww_acquire_ctx *ww_ctx)
+{
+       return 0;
+}
+
+#else
+# define build_ww_mutex()      (true)
+# define ww_container_of(rtm)  container_of(rtm, struct ww_mutex, base)
+# include "ww_mutex.h"
+#endif
+
 /*
  * lock->owner state tracking:
  *
@@ -308,7 +343,28 @@ static __always_inline int rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
 
 static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_node *b)
 {
-       return rt_mutex_waiter_less(__node_2_waiter(a), __node_2_waiter(b));
+       struct rt_mutex_waiter *aw = __node_2_waiter(a);
+       struct rt_mutex_waiter *bw = __node_2_waiter(b);
+
+       if (rt_mutex_waiter_less(aw, bw))
+               return 1;
+
+       if (!build_ww_mutex())
+               return 0;
+
+       if (rt_mutex_waiter_less(bw, aw))
+               return 0;
+
+       /* NOTE: relies on waiter->ww_ctx being set before insertion */
+       if (aw->ww_ctx) {
+               if (!bw->ww_ctx)
+                       return 1;
+
+               return (signed long)(aw->ww_ctx->stamp -
+                                    bw->ww_ctx->stamp) < 0;
+       }
+
+       return 0;
 }
 
 static __always_inline void
@@ -961,6 +1017,7 @@ takeit:
 static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
                                           struct rt_mutex_waiter *waiter,
                                           struct task_struct *task,
+                                          struct ww_acquire_ctx *ww_ctx,
                                           enum rtmutex_chainwalk chwalk)
 {
        struct task_struct *owner = rt_mutex_owner(lock);
@@ -996,6 +1053,16 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
 
        raw_spin_unlock(&task->pi_lock);
 
+       if (build_ww_mutex() && ww_ctx) {
+               struct rt_mutex *rtm;
+
+               /* Check whether the waiter should back out immediately */
+               rtm = container_of(lock, struct rt_mutex, rtmutex);
+               res = __ww_mutex_add_waiter(waiter, rtm, ww_ctx);
+               if (res)
+                       return res;
+       }
+
        if (!owner)
                return 0;
 
@@ -1281,6 +1348,7 @@ static void __sched remove_waiter(struct rt_mutex_base *lock,
 /**
  * rt_mutex_slowlock_block() - Perform the wait-wake-try-to-take loop
  * @lock:               the rt_mutex to take
+ * @ww_ctx:             WW mutex context pointer
  * @state:              the state the task should block in (TASK_INTERRUPTIBLE
  *                      or TASK_UNINTERRUPTIBLE)
  * @timeout:            the pre-initialized and started timer, or NULL for none
@@ -1289,10 +1357,12 @@ static void __sched remove_waiter(struct rt_mutex_base *lock,
  * Must be called with lock->wait_lock held and interrupts disabled
  */
 static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
+                                          struct ww_acquire_ctx *ww_ctx,
                                           unsigned int state,
                                           struct hrtimer_sleeper *timeout,
                                           struct rt_mutex_waiter *waiter)
 {
+       struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
        int ret = 0;
 
        for (;;) {
@@ -1309,6 +1379,12 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
                        break;
                }
 
+               if (build_ww_mutex() && ww_ctx) {
+                       ret = __ww_mutex_check_kill(rtm, waiter, ww_ctx);
+                       if (ret)
+                               break;
+               }
+
                raw_spin_unlock_irq(&lock->wait_lock);
 
                schedule();
@@ -1331,6 +1407,9 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
        if (res != -EDEADLOCK || detect_deadlock)
                return;
 
+       if (build_ww_mutex() && w->ww_ctx)
+               return;
+
        /*
         * Yell loudly and stop the task right here.
         */
@@ -1344,31 +1423,46 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
 /**
  * __rt_mutex_slowlock - Locking slowpath invoked with lock::wait_lock held
  * @lock:      The rtmutex to block lock
+ * @ww_ctx:    WW mutex context pointer
  * @state:     The task state for sleeping
  * @chwalk:    Indicator whether full or partial chainwalk is requested
  * @waiter:    Initializer waiter for blocking
  */
 static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
+                                      struct ww_acquire_ctx *ww_ctx,
                                       unsigned int state,
                                       enum rtmutex_chainwalk chwalk,
                                       struct rt_mutex_waiter *waiter)
 {
+       struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
+       struct ww_mutex *ww = ww_container_of(rtm);
        int ret;
 
        lockdep_assert_held(&lock->wait_lock);
 
        /* Try to acquire the lock again: */
-       if (try_to_take_rt_mutex(lock, current, NULL))
+       if (try_to_take_rt_mutex(lock, current, NULL)) {
+               if (build_ww_mutex() && ww_ctx) {
+                       __ww_mutex_check_waiters(rtm, ww_ctx);
+                       ww_mutex_lock_acquired(ww, ww_ctx);
+               }
                return 0;
+       }
 
        set_current_state(state);
 
-       ret = task_blocks_on_rt_mutex(lock, waiter, current, chwalk);
-
+       ret = task_blocks_on_rt_mutex(lock, waiter, current, ww_ctx, chwalk);
        if (likely(!ret))
-               ret = rt_mutex_slowlock_block(lock, state, NULL, waiter);
-
-       if (unlikely(ret)) {
+               ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter);
+
+       if (likely(!ret)) {
+               /* acquired the lock */
+               if (build_ww_mutex() && ww_ctx) {
+                       if (!ww_ctx->is_wait_die)
+                               __ww_mutex_check_waiters(rtm, ww_ctx);
+                       ww_mutex_lock_acquired(ww, ww_ctx);
+               }
+       } else {
                __set_current_state(TASK_RUNNING);
                remove_waiter(lock, waiter);
                rt_mutex_handle_deadlock(ret, chwalk, waiter);
@@ -1383,14 +1477,17 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
 }
 
 static inline int __rt_mutex_slowlock_locked(struct rt_mutex_base *lock,
+                                            struct ww_acquire_ctx *ww_ctx,
                                             unsigned int state)
 {
        struct rt_mutex_waiter waiter;
        int ret;
 
        rt_mutex_init_waiter(&waiter);
+       waiter.ww_ctx = ww_ctx;
 
-       ret = __rt_mutex_slowlock(lock, state, RT_MUTEX_MIN_CHAINWALK, &waiter);
+       ret = __rt_mutex_slowlock(lock, ww_ctx, state, RT_MUTEX_MIN_CHAINWALK,
+                                 &waiter);
 
        debug_rt_mutex_free_waiter(&waiter);
        return ret;
@@ -1399,9 +1496,11 @@ static inline int __rt_mutex_slowlock_locked(struct rt_mutex_base *lock,
 /*
  * rt_mutex_slowlock - Locking slowpath invoked when fast path fails
  * @lock:      The rtmutex to block lock
+ * @ww_ctx:    WW mutex context pointer
  * @state:     The task state for sleeping
  */
 static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
+                                    struct ww_acquire_ctx *ww_ctx,
                                     unsigned int state)
 {
        unsigned long flags;
@@ -1416,7 +1515,7 @@ static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
         * irqsave/restore variants.
         */
        raw_spin_lock_irqsave(&lock->wait_lock, flags);
-       ret = __rt_mutex_slowlock_locked(lock, state);
+       ret = __rt_mutex_slowlock_locked(lock, ww_ctx, state);
        raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
 
        return ret;
@@ -1428,7 +1527,7 @@ static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
        if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
                return 0;
 
-       return rt_mutex_slowlock(lock, state);
+       return rt_mutex_slowlock(lock, NULL, state);
 }
 #endif /* RT_MUTEX_BUILD_MUTEX */
 
@@ -1455,7 +1554,7 @@ static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock)
        /* Save current state and set state to TASK_RTLOCK_WAIT */
        current_save_and_set_rtlock_wait_state();
 
-       task_blocks_on_rt_mutex(lock, &waiter, current, RT_MUTEX_MIN_CHAINWALK);
+       task_blocks_on_rt_mutex(lock, &waiter, current, NULL, RT_MUTEX_MIN_CHAINWALK);
 
        for (;;) {
                /* Try to acquire the lock again */

diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c
index 7f3ac09..16126fc 100644 (file)
--- a/kernel/locking/rtmutex_api.c
+++ b/kernel/locking/rtmutex_api.c
@@ -267,7 +267,7 @@ int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
                return 1;
 
        /* We enforce deadlock detection for futexes */
-       ret = task_blocks_on_rt_mutex(lock, waiter, task,
+       ret = task_blocks_on_rt_mutex(lock, waiter, task, NULL,
                                      RT_MUTEX_FULL_CHAINWALK);
 
        if (ret && !rt_mutex_owner(lock)) {
@@ -343,7 +343,7 @@ int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock,
        raw_spin_lock_irq(&lock->wait_lock);
        /* sleep on the mutex */
        set_current_state(TASK_INTERRUPTIBLE);
-       ret = rt_mutex_slowlock_block(lock, TASK_INTERRUPTIBLE, to, waiter);
+       ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter);
        /*
         * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
         * have to fix that up.

diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index ccf0e36..61256de 100644 (file)
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -28,6 +28,7 @@
  * @wake_state:                Wakeup state to use (TASK_NORMAL or TASK_RTLOCK_WAIT)
  * @prio:              Priority of the waiter
  * @deadline:          Deadline of the waiter if applicable
+ * @ww_ctx:            WW context pointer
  */
 struct rt_mutex_waiter {
        struct rb_node          tree_entry;
@@ -37,6 +38,7 @@ struct rt_mutex_waiter {
        unsigned int            wake_state;
        int                     prio;
        u64                     deadline;
+       struct ww_acquire_ctx   *ww_ctx;
 };
 
 /**

diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 2847833..9215b4d 100644 (file)
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1360,7 +1360,7 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
        __rt_mutex_lock(rtm, state)
 
 #define rwbase_rtmutex_slowlock_locked(rtm, state)     \
-       __rt_mutex_slowlock_locked(rtm, state)
+       __rt_mutex_slowlock_locked(rtm, NULL, state)
 
 #define rwbase_rtmutex_unlock(rtm)                     \
        __rt_mutex_unlock(rtm)