cregit-Linux how code gets into the kernel

Release 4.12 include/linux/rculist_nulls.h

Directory: include/linux
#ifndef _LINUX_RCULIST_NULLS_H

#define _LINUX_RCULIST_NULLS_H

#ifdef __KERNEL__

/*
 * RCU-protected list version
 */
#include <linux/list_nulls.h>
#include <linux/rcupdate.h>

/**
 * hlist_nulls_del_init_rcu - deletes entry from hash list with re-initialization
 * @n: the element to delete from the hash list.
 *
 * Note: hlist_nulls_unhashed() on the node return true after this. It is
 * useful for RCU based read lockfree traversal if the writer side
 * must know if the list entry is still hashed or already unhashed.
 *
 * In particular, it means that we can not poison the forward pointers
 * that may still be used for walking the hash list and we can only
 * zero the pprev pointer so list_unhashed() will return true after
 * this.
 *
 * The caller must take whatever precautions are necessary (such as
 * holding appropriate locks) to avoid racing with another
 * list-mutation primitive, such as hlist_nulls_add_head_rcu() or
 * hlist_nulls_del_rcu(), running on this same list.  However, it is
 * perfectly legal to run concurrently with the _rcu list-traversal
 * primitives, such as hlist_nulls_for_each_entry_rcu().
 */

static inline void hlist_nulls_del_init_rcu(struct hlist_nulls_node *n) { if (!hlist_nulls_unhashed(n)) { __hlist_nulls_del(n); n->pprev = NULL; } }

Contributors

PersonTokensPropCommitsCommitProp
Eric Dumazet33100.00%1100.00%
Total33100.00%1100.00%

#define hlist_nulls_first_rcu(head) \ (*((struct hlist_nulls_node __rcu __force **)&(head)->first)) #define hlist_nulls_next_rcu(node) \ (*((struct hlist_nulls_node __rcu __force **)&(node)->next)) /** * hlist_nulls_del_rcu - deletes entry from hash list without re-initialization * @n: the element to delete from the hash list. * * Note: hlist_nulls_unhashed() on entry does not return true after this, * the entry is in an undefined state. It is useful for RCU based * lockfree traversal. * * In particular, it means that we can not poison the forward * pointers that may still be used for walking the hash list. * * The caller must take whatever precautions are necessary * (such as holding appropriate locks) to avoid racing * with another list-mutation primitive, such as hlist_nulls_add_head_rcu() * or hlist_nulls_del_rcu(), running on this same list. * However, it is perfectly legal to run concurrently with * the _rcu list-traversal primitives, such as * hlist_nulls_for_each_entry(). */
static inline void hlist_nulls_del_rcu(struct hlist_nulls_node *n) { __hlist_nulls_del(n); n->pprev = LIST_POISON2; }

Contributors

PersonTokensPropCommitsCommitProp
Eric Dumazet23100.00%1100.00%
Total23100.00%1100.00%

/** * hlist_nulls_add_head_rcu * @n: the element to add to the hash list. * @h: the list to add to. * * Description: * Adds the specified element to the specified hlist_nulls, * while permitting racing traversals. * * The caller must take whatever precautions are necessary * (such as holding appropriate locks) to avoid racing * with another list-mutation primitive, such as hlist_nulls_add_head_rcu() * or hlist_nulls_del_rcu(), running on this same list. * However, it is perfectly legal to run concurrently with * the _rcu list-traversal primitives, such as * hlist_nulls_for_each_entry_rcu(), used to prevent memory-consistency * problems on Alpha CPUs. Regardless of the type of CPU, the * list-traversal primitive must be guarded by rcu_read_lock(). */
static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n, struct hlist_nulls_head *h) { struct hlist_nulls_node *first = h->first; n->next = first; n->pprev = &h->first; rcu_assign_pointer(hlist_nulls_first_rcu(h), n); if (!is_a_nulls(first)) first->pprev = &n->next; }

Contributors

PersonTokensPropCommitsCommitProp
Eric Dumazet6595.59%150.00%
Arnd Bergmann34.41%150.00%
Total68100.00%2100.00%

/** * hlist_nulls_add_tail_rcu * @n: the element to add to the hash list. * @h: the list to add to. * * Description: * Adds the specified element to the end of the specified hlist_nulls, * while permitting racing traversals. NOTE: tail insertion requires * list traversal. * * The caller must take whatever precautions are necessary * (such as holding appropriate locks) to avoid racing * with another list-mutation primitive, such as hlist_nulls_add_head_rcu() * or hlist_nulls_del_rcu(), running on this same list. * However, it is perfectly legal to run concurrently with * the _rcu list-traversal primitives, such as * hlist_nulls_for_each_entry_rcu(), used to prevent memory-consistency * problems on Alpha CPUs. Regardless of the type of CPU, the * list-traversal primitive must be guarded by rcu_read_lock(). */
static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n, struct hlist_nulls_head *h) { struct hlist_nulls_node *i, *last = NULL; for (i = hlist_nulls_first_rcu(h); !is_a_nulls(i); i = hlist_nulls_next_rcu(i)) last = i; if (last) { n->next = last->next; n->pprev = &last->next; rcu_assign_pointer(hlist_nulls_next_rcu(last), n); } else { hlist_nulls_add_head_rcu(n, h); } }

Contributors

PersonTokensPropCommitsCommitProp
Craig Gallek96100.00%1100.00%
Total96100.00%1100.00%

/** * hlist_nulls_for_each_entry_rcu - iterate over rcu list of given type * @tpos: the type * to use as a loop cursor. * @pos: the &struct hlist_nulls_node to use as a loop cursor. * @head: the head for your list. * @member: the name of the hlist_nulls_node within the struct. * * The barrier() is needed to make sure compiler doesn't cache first element [1], * as this loop can be restarted [2] * [1] Documentation/atomic_ops.txt around line 114 * [2] Documentation/RCU/rculist_nulls.txt around line 146 */ #define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \ for (({barrier();}), \ pos = rcu_dereference_raw(hlist_nulls_first_rcu(head)); \ (!is_a_nulls(pos)) && \ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \ pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos))) /** * hlist_nulls_for_each_entry_safe - * iterate over list of given type safe against removal of list entry * @tpos: the type * to use as a loop cursor. * @pos: the &struct hlist_nulls_node to use as a loop cursor. * @head: the head for your list. * @member: the name of the hlist_nulls_node within the struct. */ #define hlist_nulls_for_each_entry_safe(tpos, pos, head, member) \ for (({barrier();}), \ pos = rcu_dereference_raw(hlist_nulls_first_rcu(head)); \ (!is_a_nulls(pos)) && \ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); \ pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)); 1; });) #endif #endif

Overall Contributors

PersonTokensPropCommitsCommitProp
Eric Dumazet15954.83%240.00%
Craig Gallek9733.45%120.00%
Arnd Bergmann196.55%120.00%
Alexei Starovoitov155.17%120.00%
Total290100.00%5100.00%
Directory: include/linux
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