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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 | // SPDX-License-Identifier: GPL-2.0 #include "comm.h" #include <errno.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <linux/refcount.h> #include <linux/rbtree.h> #include <linux/zalloc.h> #include "rwsem.h" struct comm_str { char *str; struct rb_node rb_node; refcount_t refcnt; }; /* Should perhaps be moved to struct machine */ static struct rb_root comm_str_root; static struct rw_semaphore comm_str_lock = {.lock = PTHREAD_RWLOCK_INITIALIZER,}; static struct comm_str *comm_str__get(struct comm_str *cs) { if (cs && refcount_inc_not_zero(&cs->refcnt)) return cs; return NULL; } static void comm_str__put(struct comm_str *cs) { if (cs && refcount_dec_and_test(&cs->refcnt)) { down_write(&comm_str_lock); rb_erase(&cs->rb_node, &comm_str_root); up_write(&comm_str_lock); zfree(&cs->str); free(cs); } } static struct comm_str *comm_str__alloc(const char *str) { struct comm_str *cs; cs = zalloc(sizeof(*cs)); if (!cs) return NULL; cs->str = strdup(str); if (!cs->str) { free(cs); return NULL; } refcount_set(&cs->refcnt, 1); return cs; } static struct comm_str *__comm_str__findnew(const char *str, struct rb_root *root) { struct rb_node **p = &root->rb_node; struct rb_node *parent = NULL; struct comm_str *iter, *new; int cmp; while (*p != NULL) { parent = *p; iter = rb_entry(parent, struct comm_str, rb_node); /* * If we race with comm_str__put, iter->refcnt is 0 * and it will be removed within comm_str__put call * shortly, ignore it in this search. */ cmp = strcmp(str, iter->str); if (!cmp && comm_str__get(iter)) return iter; if (cmp < 0) p = &(*p)->rb_left; else p = &(*p)->rb_right; } new = comm_str__alloc(str); if (!new) return NULL; rb_link_node(&new->rb_node, parent, p); rb_insert_color(&new->rb_node, root); return new; } static struct comm_str *comm_str__findnew(const char *str, struct rb_root *root) { struct comm_str *cs; down_write(&comm_str_lock); cs = __comm_str__findnew(str, root); up_write(&comm_str_lock); return cs; } struct comm *comm__new(const char *str, u64 timestamp, bool exec) { struct comm *comm = zalloc(sizeof(*comm)); if (!comm) return NULL; comm->start = timestamp; comm->exec = exec; comm->comm_str = comm_str__findnew(str, &comm_str_root); if (!comm->comm_str) { free(comm); return NULL; } return comm; } int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec) { struct comm_str *new, *old = comm->comm_str; new = comm_str__findnew(str, &comm_str_root); if (!new) return -ENOMEM; comm_str__put(old); comm->comm_str = new; comm->start = timestamp; if (exec) comm->exec = true; return 0; } void comm__free(struct comm *comm) { comm_str__put(comm->comm_str); free(comm); } const char *comm__str(const struct comm *comm) { return comm->comm_str->str; } |