From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- lib/generic-radix-tree.c | 230 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 230 insertions(+) create mode 100644 lib/generic-radix-tree.c (limited to 'lib/generic-radix-tree.c') diff --git a/lib/generic-radix-tree.c b/lib/generic-radix-tree.c new file mode 100644 index 000000000..79e067b51 --- /dev/null +++ b/lib/generic-radix-tree.c @@ -0,0 +1,230 @@ + +#include +#include +#include +#include +#include + +/* + * Returns pointer to the specified byte @offset within @radix, or NULL if not + * allocated + */ +void *__genradix_ptr(struct __genradix *radix, size_t offset) +{ + return __genradix_ptr_inlined(radix, offset); +} +EXPORT_SYMBOL(__genradix_ptr); + +/* + * Returns pointer to the specified byte @offset within @radix, allocating it if + * necessary - newly allocated slots are always zeroed out: + */ +void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset, + struct genradix_node **preallocated, + gfp_t gfp_mask) +{ + struct genradix_root *v = READ_ONCE(radix->root); + struct genradix_node *n, *new_node = NULL; + unsigned level; + + if (preallocated) + swap(new_node, *preallocated); + + /* Increase tree depth if necessary: */ + while (1) { + struct genradix_root *r = v, *new_root; + + n = genradix_root_to_node(r); + level = genradix_root_to_depth(r); + + if (n && ilog2(offset) < genradix_depth_shift(level)) + break; + + if (!new_node) { + new_node = genradix_alloc_node(gfp_mask); + if (!new_node) + return NULL; + } + + new_node->children[0] = n; + new_root = ((struct genradix_root *) + ((unsigned long) new_node | (n ? level + 1 : 0))); + + if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) { + v = new_root; + new_node = NULL; + } else { + new_node->children[0] = NULL; + } + } + + while (level--) { + struct genradix_node **p = + &n->children[offset >> genradix_depth_shift(level)]; + offset &= genradix_depth_size(level) - 1; + + n = READ_ONCE(*p); + if (!n) { + if (!new_node) { + new_node = genradix_alloc_node(gfp_mask); + if (!new_node) + return NULL; + } + + if (!(n = cmpxchg_release(p, NULL, new_node))) + swap(n, new_node); + } + } + + if (new_node) + genradix_free_node(new_node); + + return &n->data[offset]; +} +EXPORT_SYMBOL(__genradix_ptr_alloc); + +void *__genradix_iter_peek(struct genradix_iter *iter, + struct __genradix *radix, + size_t objs_per_page) +{ + struct genradix_root *r; + struct genradix_node *n; + unsigned level, i; + + if (iter->offset == SIZE_MAX) + return NULL; + +restart: + r = READ_ONCE(radix->root); + if (!r) + return NULL; + + n = genradix_root_to_node(r); + level = genradix_root_to_depth(r); + + if (ilog2(iter->offset) >= genradix_depth_shift(level)) + return NULL; + + while (level) { + level--; + + i = (iter->offset >> genradix_depth_shift(level)) & + (GENRADIX_ARY - 1); + + while (!n->children[i]) { + size_t objs_per_ptr = genradix_depth_size(level); + + if (iter->offset + objs_per_ptr < iter->offset) { + iter->offset = SIZE_MAX; + iter->pos = SIZE_MAX; + return NULL; + } + + i++; + iter->offset = round_down(iter->offset + objs_per_ptr, + objs_per_ptr); + iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * + objs_per_page; + if (i == GENRADIX_ARY) + goto restart; + } + + n = n->children[i]; + } + + return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)]; +} +EXPORT_SYMBOL(__genradix_iter_peek); + +void *__genradix_iter_peek_prev(struct genradix_iter *iter, + struct __genradix *radix, + size_t objs_per_page, + size_t obj_size_plus_page_remainder) +{ + struct genradix_root *r; + struct genradix_node *n; + unsigned level, i; + + if (iter->offset == SIZE_MAX) + return NULL; + +restart: + r = READ_ONCE(radix->root); + if (!r) + return NULL; + + n = genradix_root_to_node(r); + level = genradix_root_to_depth(r); + + if (ilog2(iter->offset) >= genradix_depth_shift(level)) { + iter->offset = genradix_depth_size(level); + iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page; + + iter->offset -= obj_size_plus_page_remainder; + iter->pos--; + } + + while (level) { + level--; + + i = (iter->offset >> genradix_depth_shift(level)) & + (GENRADIX_ARY - 1); + + while (!n->children[i]) { + size_t objs_per_ptr = genradix_depth_size(level); + + iter->offset = round_down(iter->offset, objs_per_ptr); + iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page; + + if (!iter->offset) + return NULL; + + iter->offset -= obj_size_plus_page_remainder; + iter->pos--; + + if (!i) + goto restart; + --i; + } + + n = n->children[i]; + } + + return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)]; +} +EXPORT_SYMBOL(__genradix_iter_peek_prev); + +static void genradix_free_recurse(struct genradix_node *n, unsigned level) +{ + if (level) { + unsigned i; + + for (i = 0; i < GENRADIX_ARY; i++) + if (n->children[i]) + genradix_free_recurse(n->children[i], level - 1); + } + + genradix_free_node(n); +} + +int __genradix_prealloc(struct __genradix *radix, size_t size, + gfp_t gfp_mask) +{ + size_t offset; + + for (offset = 0; offset < size; offset += GENRADIX_NODE_SIZE) + if (!__genradix_ptr_alloc(radix, offset, NULL, gfp_mask)) + return -ENOMEM; + + return 0; +} +EXPORT_SYMBOL(__genradix_prealloc); + +void __genradix_free(struct __genradix *radix) +{ + struct genradix_root *r = xchg(&radix->root, NULL); + + genradix_free_recurse(genradix_root_to_node(r), + genradix_root_to_depth(r)); +} +EXPORT_SYMBOL(__genradix_free); -- cgit v1.3.1