[PATCH 0/6] v4l2-tracer: misc fixes and improvements

[PATCH 0/6] v4l2-tracer: misc fixes and improvements

[Deborah Brouwer]

This series continues to make the v4l2-tracer more robust
by fixing errors and integrating uAPI changes.

It depends on this series to sync with kernel headers:
https://lore.kernel.org/linux-media/cover.1701388237.git.deborah.brouwer@collabora.com/

Deborah Brouwer (6):
  v4l2-tracer: look in more places for libv4l2tracer
  v4l2-tracer: ignore single line comments when parsing headers
  v4l2-tracer: add re/tracing for MAX_NUM_BUFFERS
  v4l2-tracer: add re/tracing for AV1 controls
  v4l2-tracer: stop waiting to handle a signal
  v4l2-tracer: use stat to verify that retrace file exists

 utils/v4l2-tracer/retrace.cpp            | 19 ++++++++++---
 utils/v4l2-tracer/trace.cpp              | 12 +++++++++
 utils/v4l2-tracer/v4l2-tracer-common.h   |  1 +
 utils/v4l2-tracer/v4l2-tracer-gen.pl     |  5 ++--
 utils/v4l2-tracer/v4l2-tracer-info-gen.h |  1 +
 utils/v4l2-tracer/v4l2-tracer.cpp        | 34 +++++++++++++++++++-----
 6 files changed, 60 insertions(+), 12 deletions(-)


base-commit: c8adf732788e3ab317024553c7b2137e3a541269
-- 
2.41.0

[PATCH 1/6] v4l2-tracer: look in more places for libv4l2tracer

[Deborah Brouwer]

The v4l2-tracer already looks in the build and install directories for its
library, but now it will also look in a truncated version of the
LIBTRACER_PATH which is helpful if it was installed by a cross-build. If
all else fails, it also allows the user to set a custom path using the
LD_PRELOAD environment variable.

Exit if the libv4l2tracer.so can’t be found.

Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
---
 utils/v4l2-tracer/v4l2-tracer.cpp | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/utils/v4l2-tracer/v4l2-tracer.cpp b/utils/v4l2-tracer/v4l2-tracer.cpp
index a039f528..37e17eb6 100644
--- a/utils/v4l2-tracer/v4l2-tracer.cpp
+++ b/utils/v4l2-tracer/v4l2-tracer.cpp
@@ -306,13 +306,31 @@ int tracer(int argc, char *argv[], bool retrace)
 	else
 		idx++;
 
-	/* look for libv4l2tracer next to the executable */
 	libv4l2tracer_path = program.replace(program.begin() + idx, program.end(), "libv4l2tracer.so");
 
-	/* otherwise, use the installation path */
-	if (stat(libv4l2tracer_path.c_str(), &sb) == -1)
+	if (stat(libv4l2tracer_path.c_str(), &sb) == -1) {
+		/* If not found, get the libv4l2tracer library from the meson install path 'prefix' */
 		libv4l2tracer_path = std::string(LIBTRACER_PATH) + "/libv4l2tracer.so";
 
+		/* Otherwise, guess where the library might be for a cross-build. */
+		if (stat(libv4l2tracer_path.c_str(), &sb) == -1) {
+			std::size_t idx =  libv4l2tracer_path.find("/home");
+			libv4l2tracer_path = libv4l2tracer_path.substr(idx);
+
+			/* Finally, check if the user set a custom path using LD_PRELOAD. */
+			if (stat(libv4l2tracer_path.c_str(), &sb) == -1) {
+				if (getenv("LD_PRELOAD"))
+					libv4l2tracer_path = std::string(getenv("LD_PRELOAD"));
+
+				if (stat(libv4l2tracer_path.c_str(), &sb) == -1) {
+					fprintf(stderr, "Exiting: can't find libv4l2tracer library\n");
+					fprintf(stderr, "Set a custom libv4l2tracer library path using: LD_PRELOAD\n");
+					exit(EXIT_FAILURE);
+				}
+			}
+		}
+	}
+
 	if (is_verbose())
 		fprintf(stderr, "Loading libv4l2tracer: %s\n", libv4l2tracer_path.c_str());
 	setenv("LD_PRELOAD", libv4l2tracer_path.c_str(), 0);
@@ -355,6 +373,7 @@ int tracer(int argc, char *argv[], bool retrace)
 	fprintf(stderr, "%s", trace_filename.c_str());
 	fprintf(stderr, "\n");
 
+	unsetenv("LD_PRELOAD");
 	return exec_result;
 }
 
-- 
2.41.0

[PATCH 2/6] v4l2-tracer: ignore single line comments when parsing headers

[Deborah Brouwer]

Just in case there are single-line comments that start with '//',
ignore them in the autogeneration script.

Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
---
 utils/v4l2-tracer/v4l2-tracer-gen.pl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/utils/v4l2-tracer/v4l2-tracer-gen.pl b/utils/v4l2-tracer/v4l2-tracer-gen.pl
index 1e4cadda..7b4f859b 100755
--- a/utils/v4l2-tracer/v4l2-tracer-gen.pl
+++ b/utils/v4l2-tracer/v4l2-tracer-gen.pl
@@ -151,7 +151,8 @@ sub clean_up_line {
 	$line =~ s/^\s+//; # remove leading whitespace
 	$line =~ s/.*\# define.*//; # zero out line if it has defines inside a structure (e.g. v4l2_jpegcompression)
 	$line =~ s/^\s*\/?\s?\*.*//; # zero out line if it has comments where the line starts with start with /* / * or just *
-	$line =~ s/\s*\/\*.*//; # remove comments at the end of a line following a member
+	$line =~ s/\s*\/\*.*//; # remove comments /* */ at the end of a line following a member
+	$line =~ s/\s*\/\/.*//; # remove comments // at the end of a line following a member
 	$line =~ s/\*\/$//; # zero out line if it has comments that begin without any slashs or asterisks but end with */
 	# zero out lines that don't have a ; or { because they are comments but without any identifying slashes or asteriks
 	if ($line !~ /.*[\;|\{].*/) {
-- 
2.41.0

[PATCH 3/6] v4l2-tracer: add re/tracing for MAX_NUM_BUFFERS

[Deborah Brouwer]

In the last sync of the kernel headers, the autogeneration script failed
to pick up the new flag V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS, so add it.

Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
---
 utils/v4l2-tracer/v4l2-tracer-gen.pl     | 2 +-
 utils/v4l2-tracer/v4l2-tracer-info-gen.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/utils/v4l2-tracer/v4l2-tracer-gen.pl b/utils/v4l2-tracer/v4l2-tracer-gen.pl
index 7b4f859b..b0ec9d6e 100755
--- a/utils/v4l2-tracer/v4l2-tracer-gen.pl
+++ b/utils/v4l2-tracer/v4l2-tracer-gen.pl
@@ -943,7 +943,7 @@ while (<>) {
 	}
 	if (grep {/^#define V4L2_BUF_CAP_SUPPORTS_MMAP\s+/} $_) {
 		printf $fh_common_info_h "constexpr flag_def v4l2_buf_cap_flag_def[] = {\n";
-		flag_def_gen("V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS");
+		flag_def_gen("V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS");
 		next;
 	}
 	if (grep {/^#define V4L2_STD_PAL_B\s+/} $_) {
diff --git a/utils/v4l2-tracer/v4l2-tracer-info-gen.h b/utils/v4l2-tracer/v4l2-tracer-info-gen.h
index 332e271f..b103b9bd 100644
--- a/utils/v4l2-tracer/v4l2-tracer-info-gen.h
+++ b/utils/v4l2-tracer/v4l2-tracer-info-gen.h
@@ -1518,6 +1518,7 @@ constexpr flag_def v4l2_buf_cap_flag_def[] = {
 	{ V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS,	"V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS" },
 	{ V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF,	"V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF" },
 	{ V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS,	"V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS" },
+	{ V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS,	"V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS" },
 	{ 0, "" }
 };
 
-- 
2.41.0

[PATCH 4/6] v4l2-tracer: add re/tracing for AV1 controls

[Deborah Brouwer]

Hook up the existing autogenerated AV1 tracing and retracing functions so
that they are called by the tracer and retracer.

Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
---
 utils/v4l2-tracer/retrace.cpp | 12 ++++++++++++
 utils/v4l2-tracer/trace.cpp   | 12 ++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/utils/v4l2-tracer/retrace.cpp b/utils/v4l2-tracer/retrace.cpp
index 03fe13f8..b8a1c8fb 100644
--- a/utils/v4l2-tracer/retrace.cpp
+++ b/utils/v4l2-tracer/retrace.cpp
@@ -876,6 +876,18 @@ struct v4l2_ext_control *retrace_v4l2_ext_control(json_object *parent_obj, int c
 	case V4L2_CID_STATELESS_MPEG2_QUANTISATION:
 		p->ptr = retrace_v4l2_ctrl_mpeg2_quantisation_gen(v4l2_ext_control_obj);
 		break;
+	case V4L2_CID_STATELESS_AV1_SEQUENCE:
+		p->ptr = retrace_v4l2_ctrl_av1_sequence_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_AV1_TILE_GROUP_ENTRY:
+		p->ptr = retrace_v4l2_ctrl_av1_tile_group_entry_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_AV1_FRAME:
+		p->ptr = retrace_v4l2_ctrl_av1_frame_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_AV1_FILM_GRAIN:
+		p->ptr = retrace_v4l2_ctrl_av1_film_grain_gen(v4l2_ext_control_obj);
+		break;
 	default:
 		line_info("\n\tWarning: cannot retrace control: %s",
 		          val2s(p->id, control_val_def).c_str());
diff --git a/utils/v4l2-tracer/trace.cpp b/utils/v4l2-tracer/trace.cpp
index c4fc1584..996fb043 100644
--- a/utils/v4l2-tracer/trace.cpp
+++ b/utils/v4l2-tracer/trace.cpp
@@ -412,6 +412,18 @@ void trace_v4l2_ext_control(void *arg, json_object *parent_obj, std::string key_
 	case V4L2_CID_PIXEL_RATE:
 		json_object_object_add(v4l2_ext_control_obj, "value64", json_object_new_int64(p->value64));
 		break;
+	case V4L2_CID_STATELESS_AV1_SEQUENCE:
+		trace_v4l2_ctrl_av1_sequence_gen(p->p_av1_sequence, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_AV1_TILE_GROUP_ENTRY:
+		trace_v4l2_ctrl_av1_tile_group_entry_gen(p->p_av1_tile_group_entry, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_AV1_FRAME:
+		trace_v4l2_ctrl_av1_frame_gen(p->p_av1_frame, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_AV1_FILM_GRAIN:
+		trace_v4l2_ctrl_av1_film_grain_gen(p->p_av1_film_grain, v4l2_ext_control_obj);
+		break;
 	default:
 		if (p->size)
 			line_info("\n\tWarning: cannot trace control: %s", val2s(p->id, control_val_def).c_str());
-- 
2.41.0

[PATCH 5/6] v4l2-tracer: stop waiting to handle a signal

[Deborah Brouwer]

Usually the v4l2-tracer will wait for its tracee to handle a signal e.g.
from ctrl+c before the v4l2-tracer exits, but if there is no tracee,
then the v4l2-tracer waits forever.

Exit gracefully by waiting only if a tracee exists.

Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
---
 utils/v4l2-tracer/v4l2-tracer.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/utils/v4l2-tracer/v4l2-tracer.cpp b/utils/v4l2-tracer/v4l2-tracer.cpp
index 37e17eb6..05e5b368 100644
--- a/utils/v4l2-tracer/v4l2-tracer.cpp
+++ b/utils/v4l2-tracer/v4l2-tracer.cpp
@@ -16,9 +16,12 @@ pid_t tracee_pid = 0;
 void v4l2_tracer_sig_handler(int signum)
 {
 	line_info("\n\tReceived signum: %d", signum);
-	kill(tracee_pid, signum);
-	/* Wait for tracee to handle the signal first before v4l2-tracer exits. */
-	wait(nullptr);
+
+	/* If there is a tracee, wait for it to handle the signal first before exiting. */
+	if (tracee_pid) {
+		kill(tracee_pid, signum);
+		wait(nullptr);
+	}
 }
 
 enum Options {
-- 
2.41.0

[PATCH 6/6] v4l2-tracer: use stat to verify that retrace file exists

[Deborah Brouwer]

Instead of opening and closing the file to see if it exists, just use
stat. This avoids cluttering a trace with extra opens/closes. Also change
the return value to give a better description of the failure to the
calling function.

Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
---
 utils/v4l2-tracer/retrace.cpp          | 7 +++----
 utils/v4l2-tracer/v4l2-tracer-common.h | 1 +
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/utils/v4l2-tracer/retrace.cpp b/utils/v4l2-tracer/retrace.cpp
index b8a1c8fb..60d64d8b 100644
--- a/utils/v4l2-tracer/retrace.cpp
+++ b/utils/v4l2-tracer/retrace.cpp
@@ -1537,12 +1537,11 @@ void retrace_array(json_object *root_array_obj)
 
 int retrace(std::string trace_filename)
 {
-	FILE *trace_file = fopen(trace_filename.c_str(), "r");
-	if (trace_file == nullptr) {
+	struct stat sb;
+	if (stat(trace_filename.c_str(), &sb) == -1) {
 		line_info("\n\tTrace file error: \'%s\'", trace_filename.c_str());
-		return 1;
+		return -EINVAL;
 	}
-	fclose(trace_file);
 
 	fprintf(stderr, "Retracing: %s\n", trace_filename.c_str());
 
diff --git a/utils/v4l2-tracer/v4l2-tracer-common.h b/utils/v4l2-tracer/v4l2-tracer-common.h
index c8b5dbd4..adb41218 100644
--- a/utils/v4l2-tracer/v4l2-tracer-common.h
+++ b/utils/v4l2-tracer/v4l2-tracer-common.h
@@ -26,6 +26,7 @@
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <unistd.h>
 #include <unordered_map>
 #include <vector>
-- 
2.41.0