A fix for https://bugzilla.kernel.org/show_bug.cgi?id=203411
When trace-cmd is running in "profile" mode, trace files are not generated.
Instead, pipes are used to collect trace data from recorder threads. Some
internal functions, originally designed for working with files, are reused
in pipes use case:
init_cpu()
allocate_page()
get_next_page()
There was an undesired behaviour in those functions, when working with pipes,
which causes the segmentation fault, described in the bug report.
Signed-off-by: Tzvetomir Stoyanov <tstoyanov@xxxxxxxxxx>
---
lib/trace-cmd/trace-input.c | 45 +++++++++++++++++++++++++++----------
1 file changed, 33 insertions(+), 12 deletions(-)
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index ba20ef1..264e3c3 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -28,8 +28,6 @@
/* for debugging read instead of mmap */
static int force_read = 0;
-#define PAGE_STOPPER ((struct page *)-1L)
-
struct page_map {
struct list_head list;
off64_t offset;
@@ -65,6 +63,7 @@ struct cpu_data {
struct tep_record *next;
struct page *page;
struct kbuffer *kbuf;
+ int nr_pages;
int page_cnt;
int cpu;
int pipe_fd;
@@ -146,16 +145,17 @@ static void add_record(struct page *page, struct tep_record *record)
record->prev = NULL;
page->records = record;
}
-static const char *show_records(struct page **pages)
+static const char *show_records(struct page **pages, int nr_pages)
{
static char buf[BUFSIZ + 1];
struct tep_record *record;
struct page *page;
int len;
+ int i;
memset(buf, 0, sizeof(buf));
len = 0;
- for (i = 0; pages[i] != PAGE_STOPPER; i--) {
+ for (i = 0; i < nr_pages; i++) {
page = pages[i];
if (!page)
continue;
@@ -172,7 +172,7 @@ static const char *show_records(struct page **pages)
#else
static inline void remove_record(struct page *page, struct tep_record *record) {}
static inline void add_record(struct page *page, struct tep_record *record) {}
-static const char *show_records(struct page **pages)
+static const char *show_records(struct page **pages, int nr_pages)
{
return "";
}
@@ -919,10 +919,20 @@ static struct page *allocate_page(struct tracecmd_input *handle,
int cpu, off64_t offset)
{
struct cpu_data *cpu_data = &handle->cpu_data[cpu];
+ struct page **pages;
struct page *page;
int index;
index = (offset - cpu_data->file_offset) / handle->page_size;
+ if (index >= cpu_data->nr_pages) {
+ pages = realloc(cpu_data->pages, (index + 1) * sizeof(*cpu_data->pages));
+ if (!pages)
+ return NULL;
+ memset(pages + cpu_data->nr_pages, 0,
+ (index + 1 - cpu_data->nr_pages) * sizeof(*cpu_data->pages));
+ cpu_data->pages = pages;
+ cpu_data->nr_pages = index + 1;
+ }
if (cpu_data->pages[index]) {
cpu_data->pages[index]->ref_count++;
return cpu_data->pages[index];
@@ -954,6 +964,7 @@ static struct page *allocate_page(struct tracecmd_input *handle,
static void __free_page(struct tracecmd_input *handle, struct page *page)
{
struct cpu_data *cpu_data = &handle->cpu_data[page->cpu];
+ struct page **pages;
int index;
if (!page->ref_count)
@@ -973,6 +984,17 @@ static void __free_page(struct tracecmd_input *handle, struct page *page)
cpu_data->page_cnt--;
free(page);
+
+ for (index = cpu_data->nr_pages - 1; index > 0; index--)
+ if (cpu_data->pages[index])
+ break;
+ if (index < (cpu_data->nr_pages - 1)) {
+ pages = realloc(cpu_data->pages, (index + 1) * sizeof(*cpu_data->pages));
+ if (!pages)
+ return;
+ cpu_data->pages = pages;
+ cpu_data->nr_pages = index + 1;
+ }
}
static void free_page(struct tracecmd_input *handle, int cpu)
@@ -2026,7 +2048,6 @@ tracecmd_read_prev(struct tracecmd_input *handle, struct tep_record *record)
static int init_cpu(struct tracecmd_input *handle, int cpu)
{
struct cpu_data *cpu_data = &handle->cpu_data[cpu];
- int num_pages;
int i;
cpu_data->offset = cpu_data->file_offset;
@@ -2040,14 +2061,13 @@ static int init_cpu(struct tracecmd_input *handle, int cpu)
return 0;
}
- num_pages = (cpu_data->size + handle->page_size - 1) / handle->page_size;
- cpu_data->pages = calloc(num_pages + 1, sizeof(*cpu_data->pages));
+ cpu_data->nr_pages = (cpu_data->size + handle->page_size - 1) / handle->page_size;
+ if (!cpu_data->nr_pages)
+ cpu_data->nr_pages = 1;
+ cpu_data->pages = calloc(cpu_data->nr_pages, sizeof(*cpu_data->pages));
if (!cpu_data->pages)
return -1;
- /* Add stopper */
- cpu_data->pages[num_pages] = PAGE_STOPPER;
-
if (handle->use_pipe) {
/* Just make a page, it will be nuked later */
cpu_data->page = malloc(sizeof(*cpu_data->page));
@@ -2793,7 +2813,8 @@ void tracecmd_close(struct tracecmd_input *handle)
if (handle->cpu_data[cpu].page_cnt)
warning("%d pages still allocated on cpu %d%s",
handle->cpu_data[cpu].page_cnt,
- cpu, show_records(handle->cpu_data[cpu].pages));
+ cpu, show_records(handle->cpu_data[cpu].pages,
+ handle->cpu_data[cpu].nr_pages));
free(handle->cpu_data[cpu].pages);
}
}
--
2.21.0
|