From 6699ed712a97f70267e017f509126b890f6f6b28 Mon Sep 17 00:00:00 2001 From: Tzvetomir Stoyanov Date: Mon, 1 Apr 2019 12:43:08 -0400 Subject: [PATCH] tools lib traceevent: Implement a new API, tep_list_events_copy() Existing API tep_list_events() is not thread safe, it uses the internal array sort_events to keep cache of the sorted events and reuses it. This patch implements a new API, tep_list_events_copy(), which allocates new sorted array each time it is called. It could be used when a sorted events functionality is needed in thread safe use cases. It is up to the caller to free the array. Signed-off-by: Tzvetomir Stoyanov Cc: Andrew Morton Cc: Jiri Olsa Cc: Namhyung Kim Link: http://lore.kernel.org/linux-trace-devel/20181218133013.31094-1-tstoyanov@vmware.com Link: http://lkml.kernel.org/r/20190401164343.117437443@goodmis.org Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/traceevent/event-parse.c | 117 ++++++++++++++++++++++------- tools/lib/traceevent/event-parse.h | 5 +- 2 files changed, 95 insertions(+), 27 deletions(-) diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c index 666e23ded6ed..c00aebab3c33 100644 --- a/tools/lib/traceevent/event-parse.c +++ b/tools/lib/traceevent/event-parse.c @@ -5651,33 +5651,27 @@ static int events_system_cmp(const void *a, const void *b) return events_id_cmp(a, b); } -struct tep_event **tep_list_events(struct tep_handle *pevent, enum tep_event_sort_type sort_type) +static struct tep_event **list_events_copy(struct tep_handle *tep) { struct tep_event **events; + + if (!tep) + return NULL; + + events = malloc(sizeof(*events) * (tep->nr_events + 1)); + if (!events) + return NULL; + + memcpy(events, tep->events, sizeof(*events) * tep->nr_events); + events[tep->nr_events] = NULL; + return events; +} + +static void list_events_sort(struct tep_event **events, int nr_events, + enum tep_event_sort_type sort_type) +{ int (*sort)(const void *a, const void *b); - events = pevent->sort_events; - - if (events && pevent->last_type == sort_type) - return events; - - if (!events) { - events = malloc(sizeof(*events) * (pevent->nr_events + 1)); - if (!events) - return NULL; - - memcpy(events, pevent->events, sizeof(*events) * pevent->nr_events); - events[pevent->nr_events] = NULL; - - pevent->sort_events = events; - - /* the internal events are sorted by id */ - if (sort_type == TEP_EVENT_SORT_ID) { - pevent->last_type = sort_type; - return events; - } - } - switch (sort_type) { case TEP_EVENT_SORT_ID: sort = events_id_cmp; @@ -5689,11 +5683,82 @@ struct tep_event **tep_list_events(struct tep_handle *pevent, enum tep_event_sor sort = events_system_cmp; break; default: - return events; + sort = NULL; } - qsort(events, pevent->nr_events, sizeof(*events), sort); - pevent->last_type = sort_type; + if (sort) + qsort(events, nr_events, sizeof(*events), sort); +} + +/** + * tep_list_events - Get events, sorted by given criteria. + * @tep: a handle to the tep context + * @sort_type: desired sort order of the events in the array + * + * Returns an array of pointers to all events, sorted by the given + * @sort_type criteria. The last element of the array is NULL. The returned + * memory must not be freed, it is managed by the library. + * The function is not thread safe. + */ +struct tep_event **tep_list_events(struct tep_handle *tep, + enum tep_event_sort_type sort_type) +{ + struct tep_event **events; + + if (!tep) + return NULL; + + events = tep->sort_events; + if (events && tep->last_type == sort_type) + return events; + + if (!events) { + events = list_events_copy(tep); + if (!events) + return NULL; + + tep->sort_events = events; + + /* the internal events are sorted by id */ + if (sort_type == TEP_EVENT_SORT_ID) { + tep->last_type = sort_type; + return events; + } + } + + list_events_sort(events, tep->nr_events, sort_type); + tep->last_type = sort_type; + + return events; +} + + +/** + * tep_list_events_copy - Thread safe version of tep_list_events() + * @tep: a handle to the tep context + * @sort_type: desired sort order of the events in the array + * + * Returns an array of pointers to all events, sorted by the given + * @sort_type criteria. The last element of the array is NULL. The returned + * array is newly allocated inside the function and must be freed by the caller + */ +struct tep_event **tep_list_events_copy(struct tep_handle *tep, + enum tep_event_sort_type sort_type) +{ + struct tep_event **events; + + if (!tep) + return NULL; + + events = list_events_copy(tep); + if (!events) + return NULL; + + /* the internal events are sorted by id */ + if (sort_type == TEP_EVENT_SORT_ID) + return events; + + list_events_sort(events, tep->nr_events, sort_type); return events; } diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h index aec48f2aea8a..41159358abc2 100644 --- a/tools/lib/traceevent/event-parse.h +++ b/tools/lib/traceevent/event-parse.h @@ -544,7 +544,10 @@ void tep_event_info(struct trace_seq *s, struct tep_event *event, int tep_strerror(struct tep_handle *pevent, enum tep_errno errnum, char *buf, size_t buflen); -struct tep_event **tep_list_events(struct tep_handle *pevent, enum tep_event_sort_type); +struct tep_event **tep_list_events(struct tep_handle *tep, + enum tep_event_sort_type); +struct tep_event **tep_list_events_copy(struct tep_handle *tep, + enum tep_event_sort_type); struct tep_format_field **tep_event_common_fields(struct tep_event *event); struct tep_format_field **tep_event_fields(struct tep_event *event);