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author | Ingo Molnar <mingo@kernel.org> | 2024-01-02 12:41:38 +0300 |
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committer | Ingo Molnar <mingo@kernel.org> | 2024-01-02 12:41:38 +0300 |
commit | 67a1723344cfe05430977483d6d3c7a999480143 (patch) | |
tree | f27e4398049f485c3fa44322e4f3ddde10796f8c /kernel/locking | |
parent | a51749ab34d9e5dec548fe38ede7e01e8bb26454 (diff) | |
parent | 610a9b8f49fbcf1100716370d3b5f6f884a2835a (diff) | |
download | linux-67a1723344cfe05430977483d6d3c7a999480143.tar.xz |
Merge tag 'v6.7-rc8' into locking/core, to pick up dependent changes
Pick up these commits from Linus's tree:
b106bcf0f99a ("locking/osq_lock: Clarify osq_wait_next()")
563adbfc351b ("locking/osq_lock: Clarify osq_wait_next() calling convention")
7c2230982129 ("locking/osq_lock: Move the definition of optimistic_spin_node into osq_lock.c")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking')
-rw-r--r-- | kernel/locking/lockdep.c | 3 | ||||
-rw-r--r-- | kernel/locking/osq_lock.c | 37 |
2 files changed, 22 insertions, 18 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index e85b5ad3e206..151bd3de5936 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3497,7 +3497,8 @@ static int alloc_chain_hlocks(int req) size = chain_block_size(curr); if (likely(size >= req)) { del_chain_block(0, size, chain_block_next(curr)); - add_chain_block(curr + req, size - req); + if (size > req) + add_chain_block(curr + req, size - req); return curr; } } diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c index d5610ad52b92..75a6f6133866 100644 --- a/kernel/locking/osq_lock.c +++ b/kernel/locking/osq_lock.c @@ -11,6 +11,13 @@ * called from interrupt context and we have preemption disabled while * spinning. */ + +struct optimistic_spin_node { + struct optimistic_spin_node *next, *prev; + int locked; /* 1 if lock acquired */ + int cpu; /* encoded CPU # + 1 value */ +}; + static DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node, osq_node); /* @@ -37,32 +44,28 @@ static inline struct optimistic_spin_node *decode_cpu(int encoded_cpu_val) /* * Get a stable @node->next pointer, either for unlock() or unqueue() purposes. * Can return NULL in case we were the last queued and we updated @lock instead. + * + * If osq_lock() is being cancelled there must be a previous node + * and 'old_cpu' is its CPU #. + * For osq_unlock() there is never a previous node and old_cpu is + * set to OSQ_UNLOCKED_VAL. */ static inline struct optimistic_spin_node * osq_wait_next(struct optimistic_spin_queue *lock, struct optimistic_spin_node *node, - struct optimistic_spin_node *prev) + int old_cpu) { - struct optimistic_spin_node *next = NULL; int curr = encode_cpu(smp_processor_id()); - int old; - - /* - * If there is a prev node in queue, then the 'old' value will be - * the prev node's CPU #, else it's set to OSQ_UNLOCKED_VAL since if - * we're currently last in queue, then the queue will then become empty. - */ - old = prev ? prev->cpu : OSQ_UNLOCKED_VAL; for (;;) { if (atomic_read(&lock->tail) == curr && - atomic_cmpxchg_acquire(&lock->tail, curr, old) == curr) { + atomic_cmpxchg_acquire(&lock->tail, curr, old_cpu) == curr) { /* * We were the last queued, we moved @lock back. @prev * will now observe @lock and will complete its * unlock()/unqueue(). */ - break; + return NULL; } /* @@ -76,15 +79,15 @@ osq_wait_next(struct optimistic_spin_queue *lock, * wait for a new @node->next from its Step-C. */ if (node->next) { + struct optimistic_spin_node *next; + next = xchg(&node->next, NULL); if (next) - break; + return next; } cpu_relax(); } - - return next; } bool osq_lock(struct optimistic_spin_queue *lock) @@ -186,7 +189,7 @@ bool osq_lock(struct optimistic_spin_queue *lock) * back to @prev. */ - next = osq_wait_next(lock, node, prev); + next = osq_wait_next(lock, node, prev->cpu); if (!next) return false; @@ -226,7 +229,7 @@ void osq_unlock(struct optimistic_spin_queue *lock) return; } - next = osq_wait_next(lock, node, NULL); + next = osq_wait_next(lock, node, OSQ_UNLOCKED_VAL); if (next) WRITE_ONCE(next->locked, 1); } |