Messages in this thread | | | From | Sasha Levin <> | Date | Mon, 29 Oct 2012 13:29:24 -0400 | Subject | Re: [PATCH v7 06/16] tracepoint: use new hashtable implementation |
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On Mon, Oct 29, 2012 at 7:35 AM, Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote: > * Sasha Levin (levinsasha928@gmail.com) 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 | 27 +++++++++++---------------- >> 1 file changed, 11 insertions(+), 16 deletions(-) >> >> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c >> index d96ba22..854df92 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]; >> +static DEFINE_HASHTABLE(tracepoint_table, TRACEPOINT_HASH_BITS); >> > [...] >> >> @@ -722,6 +715,8 @@ struct notifier_block tracepoint_module_nb = { >> >> static int init_tracepoints(void) >> { >> + hash_init(tracepoint_table); >> + >> return register_module_notifier(&tracepoint_module_nb); >> } >> __initcall(init_tracepoints); > > So we have a hash table defined in .bss (therefore entirely initialized > to NULL), and you add a call to "hash_init", which iterates on the whole > array and initialize it to NULL (again) ? > > This extra initialization is redundant. I think it should be removed > from here, and hashtable.h should document that hash_init() don't need > to be called on zeroed memory (which includes static/global variables, > kzalloc'd memory, etc).
This was discussed in the previous series, the conclusion was to call hash_init() either way to keep the encapsulation and consistency.
It's cheap enough and happens only once, so why not?
Thanks, Sasha
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