[PATCH v2 10/13] perf header: add a buffer to struct feat_fd

From: David Carrillo-Cisneros
Date: Tue May 23 2017 - 03:51:18 EST


Extend struct feat_fd to use a temporal buffer in pipe-mode, rather
than a perf.data file.

Revamp write_pmu_mappings to avoid seeking so that is compatible with
pipe-mode.

Print an error when trying to use buf in features that do not support
pipe-mode.

Signed-off-by: David Carrillo-Cisneros <davidcc@xxxxxxxxxx>
---
tools/perf/util/header.c | 79 +++++++++++++++++++++++++++++++++++++-----------
1 file changed, 62 insertions(+), 17 deletions(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 65cd2d1f1721..b7704b30ed52 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -60,6 +60,7 @@ struct perf_file_attr {
struct feat_fd {
struct perf_header *ph;
int fd;
+ void *buf; /* Either buf != NULL or fd >= 0 */
ssize_t offset;
size_t size;
};
@@ -82,11 +83,27 @@ bool perf_header__has_feat(const struct perf_header *header, int feat)
/* Return: 0 if succeded, -ERR if failed. */
int do_write(struct feat_fd *fd, const void *buf, size_t size)
{
- ssize_t ret;
+ void *addr;

- ret = writen(fd->fd, buf, size);
- if (ret != (ssize_t)size)
- return ret < 0 ? (int)ret: -1;
+ if (!fd->buf) {
+ ssize_t ret = writen(fd->fd, buf, size);
+
+ if (ret != (ssize_t)size)
+ return ret < 0 ? (int)ret : -1;
+ return 0;
+ }
+retry:
+ if (size > (fd->size - fd->offset)) {
+ addr = realloc(fd->buf, fd->size << 1);
+ if (!addr)
+ return -ENOSPC;
+ fd->buf = addr;
+ fd->size <<= 1;
+ goto retry;
+ }
+
+ memcpy(fd->buf + fd->offset, buf, size);
+ fd->offset += size;

return 0;
}
@@ -126,10 +143,21 @@ static int do_write_string(struct feat_fd *fd, const char *str)

static int __do_read(struct feat_fd *fd, void *addr, ssize_t size)
{
- ssize_t ret = readn(fd->fd, addr, size);
+ if (!fd->buf) {
+ ssize_t ret = readn(fd->fd, addr, size);
+
+ if (ret != (ssize_t)size)
+ return ret < 0 ? (int)ret : -1;
+ return 0;
+ }
+
+ assert((ssize_t)fd->size > fd->offset);
+ if (size > (ssize_t)fd->size - fd->offset)
+ return -1;
+
+ memcpy(addr, fd->buf + fd->offset, size);
+ fd->offset += size;

- if (ret != (ssize_t)size)
- return ret < 0 ? (int)ret : -1;
return 0;
}

@@ -187,6 +215,10 @@ static char *do_read_string(struct feat_fd *fd)
static int write_tracing_data(struct feat_fd *fd,
struct perf_evlist *evlist)
{
+ if (fd->buf) {
+ pr_err("Unsupported write_tracing_data to memory buffer.\n");
+ return -1;
+ }
return read_tracing_data(fd->fd, &evlist->entries);
}

@@ -201,6 +233,10 @@ static int write_build_id(struct feat_fd *fd,
if (!perf_session__read_build_ids(session, true))
return -1;

+ if (fd->buf) {
+ pr_err("Unsupported write_build_id to memory buffer.\n");
+ return -1;
+ }
err = perf_session__write_buildid_table(session, fd);
if (err < 0) {
pr_debug("failed to write buildid table\n");
@@ -795,11 +831,19 @@ static int write_pmu_mappings(struct feat_fd *fd,
struct perf_evlist *evlist __maybe_unused)
{
struct perf_pmu *pmu = NULL;
- off_t offset = lseek(fd->fd, 0, SEEK_CUR);
- __u32 pmu_num = 0;
+ u32 pmu_num = 0;
int ret;

- /* write real pmu_num later */
+ /*
+ * Do a first pass to count number of pmu to avoid lseek so this
+ * works in pipe mode as well.
+ */
+ while ((pmu = perf_pmu__scan(pmu))) {
+ if (!pmu->name)
+ continue;
+ pmu_num++;
+ }
+
ret = do_write(fd, &pmu_num, sizeof(pmu_num));
if (ret < 0)
return ret;
@@ -807,7 +851,6 @@ static int write_pmu_mappings(struct feat_fd *fd,
while ((pmu = perf_pmu__scan(pmu))) {
if (!pmu->name)
continue;
- pmu_num++;

ret = do_write(fd, &pmu->type, sizeof(pmu->type));
if (ret < 0)
@@ -818,12 +861,6 @@ static int write_pmu_mappings(struct feat_fd *fd,
return ret;
}

- if (pwrite(fd->fd, &pmu_num, sizeof(pmu_num), offset) != sizeof(pmu_num)) {
- /* discard all */
- lseek(fd->fd, offset, SEEK_SET);
- return -1;
- }
-
return 0;
}

@@ -909,6 +946,10 @@ static int write_auxtrace(struct feat_fd *fd,
struct perf_session *session;
int err;

+ if (fd->buf) {
+ pr_err("Unsupported write_auxtrace to memory buffer.\n");
+ return -1;
+ }
session = container_of(fd->ph, struct perf_session, header);

err = auxtrace_index__write(fd->fd, &session->auxtrace_index);
@@ -2187,6 +2228,10 @@ static int do_write_feat(struct feat_fd *fd, struct perf_header *h, int type,
if (!feat_ops[type].write)
return -1;

+ if (fd->buf) {
+ pr_err("Called %s for memory buffer.\n", __func__);
+ return -1;
+ }
(*p)->offset = lseek(fd->fd, 0, SEEK_CUR);

err = feat_ops[type].write(fd, evlist);
--
2.13.0.219.gdb65acc882-goog