Re: [RFC v2 6/7] tracepoint: use new hashtable implementation

Steven Rostedt
2012-08-05T00:36:34Z

FYI, Mathieu is the author of this file.

-- Steve

On Fri, 2012-08-03 at 16:23 +0200, Sasha Levin wrote:
> Switch tracepoints to use the new hashtable implementation. This reduces the amount of
> generic unrelated code in the tracepoints.
>
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> ---
> kernel/tracepoint.c | 26 +++++++++-----------------
> 1 files changed, 9 insertions(+), 17 deletions(-)
>
> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
> index d96ba22..b5a2650 100644
> --- a/kernel/tracepoint.c
> +++ b/kernel/tracepoint.c
> @@ -26,6 +26,7 @@
> #include <linux/slab.h>
> #include <linux/sched.h>
> #include <linux/static_key.h>
> +#include <linux/hashtable.h>
>
> extern struct tracepoint * const __start___tracepoints_ptrs[];
> extern struct tracepoint * const __stop___tracepoints_ptrs[];
> @@ -49,8 +50,7 @@ static LIST_HEAD(tracepoint_module_list);
> * Protected by tracepoints_mutex.
> */
> #define TRACEPOINT_HASH_BITS 6
> -#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
> -static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
> +DEFINE_STATIC_HASHTABLE(tracepoint_table, TRACEPOINT_HASH_BITS);
>
> /*
> * Note about RCU :
> @@ -191,16 +191,14 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
> */
> static struct tracepoint_entry *get_tracepoint(const char *name)
> {
> - struct hlist_head *head;
> struct hlist_node *node;
> struct tracepoint_entry *e;
> u32 hash = jhash(name, strlen(name), 0);
>
> - head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
> - hlist_for_each_entry(e, node, head, hlist) {
> + hash_for_each_possible(&tracepoint_table, node, e, hlist, hash)
> if (!strcmp(name, e->name))
> return e;
> - }
> +
> return NULL;
> }
>
> @@ -210,19 +208,13 @@ static struct tracepoint_entry *get_tracepoint(const char *name)
> */
> static struct tracepoint_entry *add_tracepoint(const char *name)
> {
> - struct hlist_head *head;
> - struct hlist_node *node;
> struct tracepoint_entry *e;
> size_t name_len = strlen(name) + 1;
> u32 hash = jhash(name, name_len-1, 0);
>
> - head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
> - hlist_for_each_entry(e, node, head, hlist) {
> - if (!strcmp(name, e->name)) {
> - printk(KERN_NOTICE
> - "tracepoint %s busy\n", name);
> - return ERR_PTR(-EEXIST); /* Already there */
> - }
> + if (get_tracepoint(name)) {
> + printk(KERN_NOTICE "tracepoint %s busy\n", name);
> + return ERR_PTR(-EEXIST); /* Already there */
> }
> /*
> * Using kmalloc here to allocate a variable length element. Could
> @@ -234,7 +226,7 @@ static struct tracepoint_entry *add_tracepoint(const char *name)
> memcpy(&e->name[0], name, name_len);
> e->funcs = NULL;
> e->refcount = 0;
> - hlist_add_head(&e->hlist, head);
> + hash_add(&tracepoint_table, &e->hlist, hash);
> return e;
> }
>
> @@ -244,7 +236,7 @@ static struct tracepoint_entry *add_tracepoint(const char *name)
> */
> static inline void remove_tracepoint(struct tracepoint_entry *e)
> {
> - hlist_del(&e->hlist);
> + hash_del(&e->hlist);
> kfree(e);
> }