diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-08 03:22:37 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-08 03:26:40 +0000 |
commit | 08f003891b84f52e49a5bdbc8a589fb052ac9a4e (patch) | |
tree | b7e426b4a4eb48e9e71188a2812a4c71625c35ac /debian/patches-rt/0275-futex-Make-the-futex_hash_bucket-lock-raw.patch | |
parent | Merging upstream version 4.19.260. (diff) | |
download | linux-08f003891b84f52e49a5bdbc8a589fb052ac9a4e.tar.xz linux-08f003891b84f52e49a5bdbc8a589fb052ac9a4e.zip |
Merging debian version 4.19.260-1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'debian/patches-rt/0275-futex-Make-the-futex_hash_bucket-lock-raw.patch')
-rw-r--r-- | debian/patches-rt/0275-futex-Make-the-futex_hash_bucket-lock-raw.patch | 336 |
1 files changed, 336 insertions, 0 deletions
diff --git a/debian/patches-rt/0275-futex-Make-the-futex_hash_bucket-lock-raw.patch b/debian/patches-rt/0275-futex-Make-the-futex_hash_bucket-lock-raw.patch new file mode 100644 index 000000000..b10825ac3 --- /dev/null +++ b/debian/patches-rt/0275-futex-Make-the-futex_hash_bucket-lock-raw.patch @@ -0,0 +1,336 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Wed, 26 Jun 2019 11:59:44 +0200 +Subject: [PATCH 275/342] futex: Make the futex_hash_bucket lock raw +Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=26753445b4537710a56a34c3e43828b16269f682 + +[ Upstream commit f646521aadedab78801c9befe193e2e8a0c99298 ] + +Since commit 1a1fb985f2e2b ("futex: Handle early deadlock return +correctly") we can deadlock while we attempt to acquire the HB lock if +we fail to acquire the lock. +The RT waiter (for the futex lock) is still enqueued and acquiring the +HB lock may build up a lock chain which leads to a deadlock if the owner +of the lock futex-lock holds the HB lock. + +Make the hash bucket lock raw so it does not participate in the +lockchain. + +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> +--- + kernel/futex.c | 86 +++++++++++++++++++++++++------------------------- + 1 file changed, 43 insertions(+), 43 deletions(-) + +diff --git a/kernel/futex.c b/kernel/futex.c +index 9bcfdcffb2dd..8a49dd71b233 100644 +--- a/kernel/futex.c ++++ b/kernel/futex.c +@@ -243,7 +243,7 @@ struct futex_q { + struct plist_node list; + + struct task_struct *task; +- spinlock_t *lock_ptr; ++ raw_spinlock_t *lock_ptr; + union futex_key key; + struct futex_pi_state *pi_state; + struct rt_mutex_waiter *rt_waiter; +@@ -264,7 +264,7 @@ static const struct futex_q futex_q_init = { + */ + struct futex_hash_bucket { + atomic_t waiters; +- spinlock_t lock; ++ raw_spinlock_t lock; + struct plist_head chain; + } ____cacheline_aligned_in_smp; + +@@ -952,7 +952,7 @@ static void exit_pi_state_list(struct task_struct *curr) + } + raw_spin_unlock_irq(&curr->pi_lock); + +- spin_lock(&hb->lock); ++ raw_spin_lock(&hb->lock); + raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); + raw_spin_lock(&curr->pi_lock); + /* +@@ -962,7 +962,7 @@ static void exit_pi_state_list(struct task_struct *curr) + if (head->next != next) { + /* retain curr->pi_lock for the loop invariant */ + raw_spin_unlock(&pi_state->pi_mutex.wait_lock); +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + put_pi_state(pi_state); + continue; + } +@@ -974,7 +974,7 @@ static void exit_pi_state_list(struct task_struct *curr) + + raw_spin_unlock(&curr->pi_lock); + raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + + rt_mutex_futex_unlock(&pi_state->pi_mutex); + put_pi_state(pi_state); +@@ -1523,7 +1523,7 @@ static void __unqueue_futex(struct futex_q *q) + { + struct futex_hash_bucket *hb; + +- if (WARN_ON_SMP(!q->lock_ptr || !spin_is_locked(q->lock_ptr)) ++ if (WARN_ON_SMP(!q->lock_ptr || !raw_spin_is_locked(q->lock_ptr)) + || WARN_ON(plist_node_empty(&q->list))) + return; + +@@ -1643,21 +1643,21 @@ static inline void + double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) + { + if (hb1 <= hb2) { +- spin_lock(&hb1->lock); ++ raw_spin_lock(&hb1->lock); + if (hb1 < hb2) +- spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); ++ raw_spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); + } else { /* hb1 > hb2 */ +- spin_lock(&hb2->lock); +- spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); ++ raw_spin_lock(&hb2->lock); ++ raw_spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); + } + } + + static inline void + double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) + { +- spin_unlock(&hb1->lock); ++ raw_spin_unlock(&hb1->lock); + if (hb1 != hb2) +- spin_unlock(&hb2->lock); ++ raw_spin_unlock(&hb2->lock); + } + + /* +@@ -1685,7 +1685,7 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) + if (!hb_waiters_pending(hb)) + goto out_put_key; + +- spin_lock(&hb->lock); ++ raw_spin_lock(&hb->lock); + + plist_for_each_entry_safe(this, next, &hb->chain, list) { + if (match_futex (&this->key, &key)) { +@@ -1704,7 +1704,7 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) + } + } + +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + wake_up_q(&wake_q); + out_put_key: + put_futex_key(&key); +@@ -2326,7 +2326,7 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) + + q->lock_ptr = &hb->lock; + +- spin_lock(&hb->lock); /* implies smp_mb(); (A) */ ++ raw_spin_lock(&hb->lock); /* implies smp_mb(); (A) */ + return hb; + } + +@@ -2334,7 +2334,7 @@ static inline void + queue_unlock(struct futex_hash_bucket *hb) + __releases(&hb->lock) + { +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + hb_waiters_dec(hb); + } + +@@ -2373,7 +2373,7 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) + __releases(&hb->lock) + { + __queue_me(q, hb); +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + } + + /** +@@ -2389,41 +2389,41 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) + */ + static int unqueue_me(struct futex_q *q) + { +- spinlock_t *lock_ptr; ++ raw_spinlock_t *lock_ptr; + int ret = 0; + + /* In the common case we don't take the spinlock, which is nice. */ + retry: + /* +- * q->lock_ptr can change between this read and the following spin_lock. +- * Use READ_ONCE to forbid the compiler from reloading q->lock_ptr and +- * optimizing lock_ptr out of the logic below. ++ * q->lock_ptr can change between this read and the following ++ * raw_spin_lock. Use READ_ONCE to forbid the compiler from reloading ++ * q->lock_ptr and optimizing lock_ptr out of the logic below. + */ + lock_ptr = READ_ONCE(q->lock_ptr); + if (lock_ptr != NULL) { +- spin_lock(lock_ptr); ++ raw_spin_lock(lock_ptr); + /* + * q->lock_ptr can change between reading it and +- * spin_lock(), causing us to take the wrong lock. This ++ * raw_spin_lock(), causing us to take the wrong lock. This + * corrects the race condition. + * + * Reasoning goes like this: if we have the wrong lock, + * q->lock_ptr must have changed (maybe several times) +- * between reading it and the spin_lock(). It can +- * change again after the spin_lock() but only if it was +- * already changed before the spin_lock(). It cannot, ++ * between reading it and the raw_spin_lock(). It can ++ * change again after the raw_spin_lock() but only if it was ++ * already changed before the raw_spin_lock(). It cannot, + * however, change back to the original value. Therefore + * we can detect whether we acquired the correct lock. + */ + if (unlikely(lock_ptr != q->lock_ptr)) { +- spin_unlock(lock_ptr); ++ raw_spin_unlock(lock_ptr); + goto retry; + } + __unqueue_futex(q); + + BUG_ON(q->pi_state); + +- spin_unlock(lock_ptr); ++ raw_spin_unlock(lock_ptr); + ret = 1; + } + +@@ -2445,7 +2445,7 @@ static void unqueue_me_pi(struct futex_q *q) + put_pi_state(q->pi_state); + q->pi_state = NULL; + +- spin_unlock(q->lock_ptr); ++ raw_spin_unlock(q->lock_ptr); + } + + static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, +@@ -2569,7 +2569,7 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, + */ + handle_err: + raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); +- spin_unlock(q->lock_ptr); ++ raw_spin_unlock(q->lock_ptr); + + switch (err) { + case -EFAULT: +@@ -2586,7 +2586,7 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, + break; + } + +- spin_lock(q->lock_ptr); ++ raw_spin_lock(q->lock_ptr); + raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); + + /* +@@ -2700,7 +2700,7 @@ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q, + /* + * The task state is guaranteed to be set before another task can + * wake it. set_current_state() is implemented using smp_store_mb() and +- * queue_me() calls spin_unlock() upon completion, both serializing ++ * queue_me() calls raw_spin_unlock() upon completion, both serializing + * access to the hash list and forcing another memory barrier. + */ + set_current_state(TASK_INTERRUPTIBLE); +@@ -2998,7 +2998,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, + * before __rt_mutex_start_proxy_lock() is done. + */ + raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock); +- spin_unlock(q.lock_ptr); ++ raw_spin_unlock(q.lock_ptr); + /* + * __rt_mutex_start_proxy_lock() unconditionally enqueues the @rt_waiter + * such that futex_unlock_pi() is guaranteed to observe the waiter when +@@ -3019,7 +3019,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, + ret = rt_mutex_wait_proxy_lock(&q.pi_state->pi_mutex, to, &rt_waiter); + + cleanup: +- spin_lock(q.lock_ptr); ++ raw_spin_lock(q.lock_ptr); + /* + * If we failed to acquire the lock (deadlock/signal/timeout), we must + * first acquire the hb->lock before removing the lock from the +@@ -3106,7 +3106,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) + return ret; + + hb = hash_futex(&key); +- spin_lock(&hb->lock); ++ raw_spin_lock(&hb->lock); + + /* + * Check waiters first. We do not trust user space values at +@@ -3140,7 +3140,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) + * rt_waiter. Also see the WARN in wake_futex_pi(). + */ + raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + + /* drops pi_state->pi_mutex.wait_lock */ + ret = wake_futex_pi(uaddr, uval, pi_state); +@@ -3179,7 +3179,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) + * owner. + */ + if ((ret = cmpxchg_futex_value_locked(&curval, uaddr, uval, 0))) { +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + switch (ret) { + case -EFAULT: + goto pi_faulted; +@@ -3199,7 +3199,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) + ret = (curval == uval) ? 0 : -EAGAIN; + + out_unlock: +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + out_putkey: + put_futex_key(&key); + return ret; +@@ -3372,9 +3372,9 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, + /* Queue the futex_q, drop the hb lock, wait for wakeup. */ + futex_wait_queue_me(hb, &q, to); + +- spin_lock(&hb->lock); ++ raw_spin_lock(&hb->lock); + ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to); +- spin_unlock(&hb->lock); ++ raw_spin_unlock(&hb->lock); + if (ret) + goto out_put_keys; + +@@ -3394,7 +3394,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, + * did a lock-steal - fix up the PI-state in that case. + */ + if (q.pi_state && (q.pi_state->owner != current)) { +- spin_lock(q.lock_ptr); ++ raw_spin_lock(q.lock_ptr); + ret = fixup_pi_state_owner(uaddr2, &q, current); + /* + * Drop the reference to the pi state which +@@ -3420,7 +3420,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, + pi_mutex = &q.pi_state->pi_mutex; + ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter); + +- spin_lock(q.lock_ptr); ++ raw_spin_lock(q.lock_ptr); + if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter)) + ret = 0; + +@@ -4179,7 +4179,7 @@ static int __init futex_init(void) + for (i = 0; i < futex_hashsize; i++) { + atomic_set(&futex_queues[i].waiters, 0); + plist_head_init(&futex_queues[i].chain); +- spin_lock_init(&futex_queues[i].lock); ++ raw_spin_lock_init(&futex_queues[i].lock); + } + + return 0; |