cregit-Linux how code gets into the kernel

Release 4.12 include/linux/list_nulls.h

Directory: include/linux
#ifndef _LINUX_LIST_NULLS_H

#define _LINUX_LIST_NULLS_H

#include <linux/poison.h>
#include <linux/const.h>

/*
 * Special version of lists, where end of list is not a NULL pointer,
 * but a 'nulls' marker, which can have many different values.
 * (up to 2^31 different values guaranteed on all platforms)
 *
 * In the standard hlist, termination of a list is the NULL pointer.
 * In this special 'nulls' variant, we use the fact that objects stored in
 * a list are aligned on a word (4 or 8 bytes alignment).
 * We therefore use the last significant bit of 'ptr' :
 * Set to 1 : This is a 'nulls' end-of-list marker (ptr >> 1)
 * Set to 0 : This is a pointer to some object (ptr)
 */


struct hlist_nulls_head {
	
struct hlist_nulls_node *first;
};


struct hlist_nulls_node {
	

struct hlist_nulls_node *next, **pprev;
};

#define NULLS_MARKER(value) (1UL | (((long)value) << 1))

#define INIT_HLIST_NULLS_HEAD(ptr, nulls) \
	((ptr)->first = (struct hlist_nulls_node *) NULLS_MARKER(nulls))


#define hlist_nulls_entry(ptr, type, member) container_of(ptr,type,member)


#define hlist_nulls_entry_safe(ptr, type, member) \
	({ typeof(ptr) ____ptr = (ptr); \
           !is_a_nulls(____ptr) ? hlist_nulls_entry(____ptr, type, member) : NULL; \
        })
/**
 * ptr_is_a_nulls - Test if a ptr is a nulls
 * @ptr: ptr to be tested
 *
 */

static inline int is_a_nulls(const struct hlist_nulls_node *ptr) { return ((unsigned long)ptr & 1); }

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Eric Dumazet24100.00%1100.00%
Total24100.00%1100.00%

/** * get_nulls_value - Get the 'nulls' value of the end of chain * @ptr: end of chain * * Should be called only if is_a_nulls(ptr); */
static inline unsigned long get_nulls_value(const struct hlist_nulls_node *ptr) { return ((unsigned long)ptr) >> 1; }

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Eric Dumazet25100.00%1100.00%
Total25100.00%1100.00%


static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h) { return !h->pprev; }

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Eric Dumazet19100.00%1100.00%
Total19100.00%1100.00%


static inline int hlist_nulls_empty(const struct hlist_nulls_head *h) { return is_a_nulls(READ_ONCE(h->first)); }

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Eric Dumazet2187.50%150.00%
Paul E. McKenney312.50%150.00%
Total24100.00%2100.00%


static inline void hlist_nulls_add_head(struct hlist_nulls_node *n, struct hlist_nulls_head *h) { struct hlist_nulls_node *first = h->first; n->next = first; n->pprev = &h->first; h->first = n; if (!is_a_nulls(first)) first->pprev = &n->next; }

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Pablo Neira Ayuso64100.00%1100.00%
Total64100.00%1100.00%


static inline void __hlist_nulls_del(struct hlist_nulls_node *n) { struct hlist_nulls_node *next = n->next; struct hlist_nulls_node **pprev = n->pprev; WRITE_ONCE(*pprev, next); if (!is_a_nulls(next)) next->pprev = pprev; }

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Eric Dumazet4992.45%150.00%
Paul E. McKenney47.55%150.00%
Total53100.00%2100.00%


static inline void hlist_nulls_del(struct hlist_nulls_node *n) { __hlist_nulls_del(n); n->pprev = LIST_POISON2; }

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Pablo Neira Ayuso23100.00%1100.00%
Total23100.00%1100.00%

/** * hlist_nulls_for_each_entry - iterate over list of given type * @tpos: the type * to use as a loop cursor. * @pos: the &struct hlist_node to use as a loop cursor. * @head: the head for your list. * @member: the name of the hlist_node within the struct. * */ #define hlist_nulls_for_each_entry(tpos, pos, head, member) \ for (pos = (head)->first; \ (!is_a_nulls(pos)) && \ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1;}); \ pos = pos->next) /** * hlist_nulls_for_each_entry_from - iterate over a hlist continuing from current point * @tpos: the type * to use as a loop cursor. * @pos: the &struct hlist_node to use as a loop cursor. * @member: the name of the hlist_node within the struct. * */ #define hlist_nulls_for_each_entry_from(tpos, pos, member) \ for (; (!is_a_nulls(pos)) && \ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1;}); \ pos = pos->next) #endif

Overall Contributors

PersonTokensPropCommitsCommitProp
Eric Dumazet22164.81%114.29%
Pablo Neira Ayuso8725.51%114.29%
Alexei Starovoitov123.52%114.29%
Thomas Graf82.35%114.29%
Paul E. McKenney72.05%228.57%
Ying Xue61.76%114.29%
Total341100.00%7100.00%
Directory: include/linux
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