tools lib: Add list_last_entry_or_null()

Add list_last_entry_or_null() to get the last element from a list,
returns NULL if the list is empty.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220709015033.38326-6-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Yang Jihong 2022-07-09 09:50:21 +08:00 committed by Arnaldo Carvalho de Melo
parent 97179d9d08
commit e432947ef5

View File

@ -384,6 +384,17 @@ static inline void list_splice_tail_init(struct list_head *list,
#define list_first_entry_or_null(ptr, type, member) \
(!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
/**
* list_last_entry_or_null - get the last element from a list
* @ptr: the list head to take the element from.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_head within the struct.
*
* Note that if the list is empty, it returns NULL.
*/
#define list_last_entry_or_null(ptr, type, member) \
(!list_empty(ptr) ? list_last_entry(ptr, type, member) : NULL)
/**
* list_next_entry - get the next element in list
* @pos: the type * to cursor