[PATCH] tools lib api fs: Move cgroupsfs_find_mountpoint()

[PATCH] tools lib api fs: Move cgroupsfs_find_mountpoint()

[Namhyung Kim]

Move it from tools/perf/util/cgroup.c as it can be used by other places.
Note that cgroup filesystem is different from others since it's usually
mounted separately (in v1) for each subsystem.

I just copied the code with a little modification to pass a name of
subsystem.

Suggested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/lib/api/fs/Build    |  1 +
 tools/lib/api/fs/cgroup.c | 67 +++++++++++++++++++++++++++++++++++++++
 tools/lib/api/fs/fs.h     |  2 ++
 tools/perf/util/cgroup.c  | 63 ++----------------------------------
 4 files changed, 72 insertions(+), 61 deletions(-)
 create mode 100644 tools/lib/api/fs/cgroup.c

diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
index f4ed9629ae85..0f75b28654de 100644
--- a/tools/lib/api/fs/Build
+++ b/tools/lib/api/fs/Build
@@ -1,2 +1,3 @@
 libapi-y += fs.o
 libapi-y += tracing_path.o
+libapi-y += cgroup.o
diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
new file mode 100644
index 000000000000..889a6eb4aaca
--- /dev/null
+++ b/tools/lib/api/fs/cgroup.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/stringify.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "fs.h"
+
+int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
+{
+	FILE *fp;
+	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
+	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
+	char *token, *saved_ptr = NULL;
+
+	fp = fopen("/proc/mounts", "r");
+	if (!fp)
+		return -1;
+
+	/*
+	 * in order to handle split hierarchy, we need to scan /proc/mounts
+	 * and inspect every cgroupfs mount point to find one that has
+	 * perf_event subsystem
+	 */
+	path_v1[0] = '\0';
+	path_v2[0] = '\0';
+
+	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
+				__stringify(PATH_MAX)"s %*d %*d\n",
+				mountpoint, type, tokens) == 3) {
+
+		if (!path_v1[0] && !strcmp(type, "cgroup")) {
+
+			token = strtok_r(tokens, ",", &saved_ptr);
+
+			while (token != NULL) {
+				if (subsys && !strcmp(token, subsys)) {
+					strcpy(path_v1, mountpoint);
+					break;
+				}
+				token = strtok_r(NULL, ",", &saved_ptr);
+			}
+		}
+
+		if (!path_v2[0] && !strcmp(type, "cgroup2"))
+			strcpy(path_v2, mountpoint);
+
+		if (path_v1[0] && path_v2[0])
+			break;
+	}
+	fclose(fp);
+
+	if (path_v1[0])
+		path = path_v1;
+	else if (path_v2[0])
+		path = path_v2;
+	else
+		return -1;
+
+	if (strlen(path) < maxlen) {
+		strcpy(buf, path);
+		return 0;
+	}
+	return -1;
+}
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 92d03b8396b1..936edb95e1f3 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -28,6 +28,8 @@ FS(bpf_fs)
 #undef FS
 
 
+int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys);
+
 int filename__read_int(const char *filename, int *value);
 int filename__read_ull(const char *filename, unsigned long long *value);
 int filename__read_xll(const char *filename, unsigned long long *value);
diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
index 4881d4af3381..5bc9d3b01bd9 100644
--- a/tools/perf/util/cgroup.c
+++ b/tools/perf/util/cgroup.c
@@ -3,75 +3,16 @@
 #include "evsel.h"
 #include "cgroup.h"
 #include "evlist.h"
-#include <linux/stringify.h>
 #include <linux/zalloc.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
+#include <api/fs/fs.h>
 
 int nr_cgroups;
 
-static int
-cgroupfs_find_mountpoint(char *buf, size_t maxlen)
-{
-	FILE *fp;
-	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
-	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
-	char *token, *saved_ptr = NULL;
-
-	fp = fopen("/proc/mounts", "r");
-	if (!fp)
-		return -1;
-
-	/*
-	 * in order to handle split hierarchy, we need to scan /proc/mounts
-	 * and inspect every cgroupfs mount point to find one that has
-	 * perf_event subsystem
-	 */
-	path_v1[0] = '\0';
-	path_v2[0] = '\0';
-
-	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
-				__stringify(PATH_MAX)"s %*d %*d\n",
-				mountpoint, type, tokens) == 3) {
-
-		if (!path_v1[0] && !strcmp(type, "cgroup")) {
-
-			token = strtok_r(tokens, ",", &saved_ptr);
-
-			while (token != NULL) {
-				if (!strcmp(token, "perf_event")) {
-					strcpy(path_v1, mountpoint);
-					break;
-				}
-				token = strtok_r(NULL, ",", &saved_ptr);
-			}
-		}
-
-		if (!path_v2[0] && !strcmp(type, "cgroup2"))
-			strcpy(path_v2, mountpoint);
-
-		if (path_v1[0] && path_v2[0])
-			break;
-	}
-	fclose(fp);
-
-	if (path_v1[0])
-		path = path_v1;
-	else if (path_v2[0])
-		path = path_v2;
-	else
-		return -1;
-
-	if (strlen(path) < maxlen) {
-		strcpy(buf, path);
-		return 0;
-	}
-	return -1;
-}
-
 static int open_cgroup(const char *name)
 {
 	char path[PATH_MAX + 1];
@@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
 	int fd;
 
 
-	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
+	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
 		return -1;
 
 	scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
-- 
2.25.0.341.g760bfbb309-goog

Re: [PATCH] tools lib api fs: Move cgroupsfs_find_mountpoint()

[Jiri Olsa]

On Mon, Jan 27, 2020 at 07:00:31PM +0900, Namhyung Kim wrote:

SNIP

> -
> -	if (strlen(path) < maxlen) {
> -		strcpy(buf, path);
> -		return 0;
> -	}
> -	return -1;
> -}
> -
>  static int open_cgroup(const char *name)
>  {
>  	char path[PATH_MAX + 1];
> @@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
>  	int fd;
>  
>  
> -	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
> +	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))

nice, but could you please follow fs API names and change the
name to cgroupfs__mountpoint

I think we don't need to define the rest of the functions now,
if they are not used

	#define FS(name)                                \
		const char *name##__mountpoint(void);   \
		const char *name##__mount(void);        \
		bool name##__configured(void);          \

just follow the function name

thanks,
jirka

>  		return -1;
>  
>  	scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
> -- 
> 2.25.0.341.g760bfbb309-goog
> 

Re: [PATCH] tools lib api fs: Move cgroupsfs_find_mountpoint()

[Namhyung Kim]

Hi Jiri,

On Mon, Jan 27, 2020 at 8:12 PM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Mon, Jan 27, 2020 at 07:00:31PM +0900, Namhyung Kim wrote:
>
> SNIP
>
> > -
> > -     if (strlen(path) < maxlen) {
> > -             strcpy(buf, path);
> > -             return 0;
> > -     }
> > -     return -1;
> > -}
> > -
> >  static int open_cgroup(const char *name)
> >  {
> >       char path[PATH_MAX + 1];
> > @@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
> >       int fd;
> >
> >
> > -     if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
> > +     if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
>
> nice, but could you please follow fs API names and change the
> name to cgroupfs__mountpoint
>
> I think we don't need to define the rest of the functions now,
> if they are not used
>
>         #define FS(name)                                \
>                 const char *name##__mountpoint(void);   \
>                 const char *name##__mount(void);        \
>                 bool name##__configured(void);          \
>
> just follow the function name

I thought about it too, but still it has different arguments.
So I left it as is... Do you really want to rename?

Thanks
Namhyung

Re: [PATCH] tools lib api fs: Move cgroupsfs_find_mountpoint()

[Jiri Olsa]

On Mon, Jan 27, 2020 at 11:58:27PM +0900, Namhyung Kim wrote:
> Hi Jiri,
> 
> On Mon, Jan 27, 2020 at 8:12 PM Jiri Olsa <jolsa@redhat.com> wrote:
> >
> > On Mon, Jan 27, 2020 at 07:00:31PM +0900, Namhyung Kim wrote:
> >
> > SNIP
> >
> > > -
> > > -     if (strlen(path) < maxlen) {
> > > -             strcpy(buf, path);
> > > -             return 0;
> > > -     }
> > > -     return -1;
> > > -}
> > > -
> > >  static int open_cgroup(const char *name)
> > >  {
> > >       char path[PATH_MAX + 1];
> > > @@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
> > >       int fd;
> > >
> > >
> > > -     if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
> > > +     if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
> >
> > nice, but could you please follow fs API names and change the
> > name to cgroupfs__mountpoint
> >
> > I think we don't need to define the rest of the functions now,
> > if they are not used
> >
> >         #define FS(name)                                \
> >                 const char *name##__mountpoint(void);   \
> >                 const char *name##__mount(void);        \
> >                 bool name##__configured(void);          \
> >
> > just follow the function name
> 
> I thought about it too, but still it has different arguments.
> So I left it as is... Do you really want to rename?

yea I think we should keep the same name, Arnaldo?

jirka

> 
> Thanks
> Namhyung
> 

[PATCH v2] tools lib api fs: Move cgroupsfs__mountpoint()

[Namhyung Kim]

Move it from tools/perf/util/cgroup.c as it can be used by other places.
Note that cgroup filesystem is different from others since it's usually
mounted separately (in v1) for each subsystem.

I just copied the code with a little modification to pass a name of
subsystem and renamed it to follow other APIs.

Suggested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
* rename to cgroupfs__mountpoint()

 tools/lib/api/fs/Build    |  1 +
 tools/lib/api/fs/cgroup.c | 67 +++++++++++++++++++++++++++++++++++++++
 tools/lib/api/fs/fs.h     |  2 ++
 tools/perf/util/cgroup.c  | 63 ++----------------------------------
 4 files changed, 72 insertions(+), 61 deletions(-)
 create mode 100644 tools/lib/api/fs/cgroup.c

diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
index f4ed9629ae85..0f75b28654de 100644
--- a/tools/lib/api/fs/Build
+++ b/tools/lib/api/fs/Build
@@ -1,2 +1,3 @@
 libapi-y += fs.o
 libapi-y += tracing_path.o
+libapi-y += cgroup.o
diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
new file mode 100644
index 000000000000..c7e1cdaa36e1
--- /dev/null
+++ b/tools/lib/api/fs/cgroup.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/stringify.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "fs.h"
+
+int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys)
+{
+	FILE *fp;
+	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
+	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
+	char *token, *saved_ptr = NULL;
+
+	fp = fopen("/proc/mounts", "r");
+	if (!fp)
+		return -1;
+
+	/*
+	 * in order to handle split hierarchy, we need to scan /proc/mounts
+	 * and inspect every cgroupfs mount point to find one that has
+	 * perf_event subsystem
+	 */
+	path_v1[0] = '\0';
+	path_v2[0] = '\0';
+
+	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
+				__stringify(PATH_MAX)"s %*d %*d\n",
+				mountpoint, type, tokens) == 3) {
+
+		if (!path_v1[0] && !strcmp(type, "cgroup")) {
+
+			token = strtok_r(tokens, ",", &saved_ptr);
+
+			while (token != NULL) {
+				if (subsys && !strcmp(token, subsys)) {
+					strcpy(path_v1, mountpoint);
+					break;
+				}
+				token = strtok_r(NULL, ",", &saved_ptr);
+			}
+		}
+
+		if (!path_v2[0] && !strcmp(type, "cgroup2"))
+			strcpy(path_v2, mountpoint);
+
+		if (path_v1[0] && path_v2[0])
+			break;
+	}
+	fclose(fp);
+
+	if (path_v1[0])
+		path = path_v1;
+	else if (path_v2[0])
+		path = path_v2;
+	else
+		return -1;
+
+	if (strlen(path) < maxlen) {
+		strcpy(buf, path);
+		return 0;
+	}
+	return -1;
+}
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 92d03b8396b1..07591ecbe39f 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -28,6 +28,8 @@ FS(bpf_fs)
 #undef FS
 
 
+int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys);
+
 int filename__read_int(const char *filename, int *value);
 int filename__read_ull(const char *filename, unsigned long long *value);
 int filename__read_xll(const char *filename, unsigned long long *value);
diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
index 4881d4af3381..12e466d1ec3b 100644
--- a/tools/perf/util/cgroup.c
+++ b/tools/perf/util/cgroup.c
@@ -3,75 +3,16 @@
 #include "evsel.h"
 #include "cgroup.h"
 #include "evlist.h"
-#include <linux/stringify.h>
 #include <linux/zalloc.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
+#include <api/fs/fs.h>
 
 int nr_cgroups;
 
-static int
-cgroupfs_find_mountpoint(char *buf, size_t maxlen)
-{
-	FILE *fp;
-	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
-	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
-	char *token, *saved_ptr = NULL;
-
-	fp = fopen("/proc/mounts", "r");
-	if (!fp)
-		return -1;
-
-	/*
-	 * in order to handle split hierarchy, we need to scan /proc/mounts
-	 * and inspect every cgroupfs mount point to find one that has
-	 * perf_event subsystem
-	 */
-	path_v1[0] = '\0';
-	path_v2[0] = '\0';
-
-	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
-				__stringify(PATH_MAX)"s %*d %*d\n",
-				mountpoint, type, tokens) == 3) {
-
-		if (!path_v1[0] && !strcmp(type, "cgroup")) {
-
-			token = strtok_r(tokens, ",", &saved_ptr);
-
-			while (token != NULL) {
-				if (!strcmp(token, "perf_event")) {
-					strcpy(path_v1, mountpoint);
-					break;
-				}
-				token = strtok_r(NULL, ",", &saved_ptr);
-			}
-		}
-
-		if (!path_v2[0] && !strcmp(type, "cgroup2"))
-			strcpy(path_v2, mountpoint);
-
-		if (path_v1[0] && path_v2[0])
-			break;
-	}
-	fclose(fp);
-
-	if (path_v1[0])
-		path = path_v1;
-	else if (path_v2[0])
-		path = path_v2;
-	else
-		return -1;
-
-	if (strlen(path) < maxlen) {
-		strcpy(buf, path);
-		return 0;
-	}
-	return -1;
-}
-
 static int open_cgroup(const char *name)
 {
 	char path[PATH_MAX + 1];
@@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
 	int fd;
 
 
-	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
+	if (cgroupfs__mountpoint(mnt, PATH_MAX + 1, "perf_event"))
 		return -1;
 
 	scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
-- 
2.25.0.341.g760bfbb309-goog

Re: [PATCH v2] tools lib api fs: Move cgroupsfs__mountpoint()

[Jiri Olsa]

On Tue, Jan 28, 2020 at 09:49:40AM +0900, Namhyung Kim wrote:
> Move it from tools/perf/util/cgroup.c as it can be used by other places.
> Note that cgroup filesystem is different from others since it's usually
> mounted separately (in v1) for each subsystem.
> 
> I just copied the code with a little modification to pass a name of
> subsystem and renamed it to follow other APIs.
> 
> Suggested-by: Jiri Olsa <jolsa@redhat.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Acked-by: Jiri Olsa <jolsa@redhat.com>

thanks,
jirka

> ---
> * rename to cgroupfs__mountpoint()
> 
>  tools/lib/api/fs/Build    |  1 +
>  tools/lib/api/fs/cgroup.c | 67 +++++++++++++++++++++++++++++++++++++++
>  tools/lib/api/fs/fs.h     |  2 ++
>  tools/perf/util/cgroup.c  | 63 ++----------------------------------
>  4 files changed, 72 insertions(+), 61 deletions(-)
>  create mode 100644 tools/lib/api/fs/cgroup.c
> 
> diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
> index f4ed9629ae85..0f75b28654de 100644
> --- a/tools/lib/api/fs/Build
> +++ b/tools/lib/api/fs/Build
> @@ -1,2 +1,3 @@
>  libapi-y += fs.o
>  libapi-y += tracing_path.o
> +libapi-y += cgroup.o
> diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
> new file mode 100644
> index 000000000000..c7e1cdaa36e1
> --- /dev/null
> +++ b/tools/lib/api/fs/cgroup.c
> @@ -0,0 +1,67 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/stringify.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include "fs.h"
> +
> +int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys)
> +{
> +	FILE *fp;
> +	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
> +	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
> +	char *token, *saved_ptr = NULL;
> +
> +	fp = fopen("/proc/mounts", "r");
> +	if (!fp)
> +		return -1;
> +
> +	/*
> +	 * in order to handle split hierarchy, we need to scan /proc/mounts
> +	 * and inspect every cgroupfs mount point to find one that has
> +	 * perf_event subsystem
> +	 */
> +	path_v1[0] = '\0';
> +	path_v2[0] = '\0';
> +
> +	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
> +				__stringify(PATH_MAX)"s %*d %*d\n",
> +				mountpoint, type, tokens) == 3) {
> +
> +		if (!path_v1[0] && !strcmp(type, "cgroup")) {
> +
> +			token = strtok_r(tokens, ",", &saved_ptr);
> +
> +			while (token != NULL) {
> +				if (subsys && !strcmp(token, subsys)) {
> +					strcpy(path_v1, mountpoint);
> +					break;
> +				}
> +				token = strtok_r(NULL, ",", &saved_ptr);
> +			}
> +		}
> +
> +		if (!path_v2[0] && !strcmp(type, "cgroup2"))
> +			strcpy(path_v2, mountpoint);
> +
> +		if (path_v1[0] && path_v2[0])
> +			break;
> +	}
> +	fclose(fp);
> +
> +	if (path_v1[0])
> +		path = path_v1;
> +	else if (path_v2[0])
> +		path = path_v2;
> +	else
> +		return -1;
> +
> +	if (strlen(path) < maxlen) {
> +		strcpy(buf, path);
> +		return 0;
> +	}
> +	return -1;
> +}
> diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
> index 92d03b8396b1..07591ecbe39f 100644
> --- a/tools/lib/api/fs/fs.h
> +++ b/tools/lib/api/fs/fs.h
> @@ -28,6 +28,8 @@ FS(bpf_fs)
>  #undef FS
>  
>  
> +int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys);
> +
>  int filename__read_int(const char *filename, int *value);
>  int filename__read_ull(const char *filename, unsigned long long *value);
>  int filename__read_xll(const char *filename, unsigned long long *value);
> diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
> index 4881d4af3381..12e466d1ec3b 100644
> --- a/tools/perf/util/cgroup.c
> +++ b/tools/perf/util/cgroup.c
> @@ -3,75 +3,16 @@
>  #include "evsel.h"
>  #include "cgroup.h"
>  #include "evlist.h"
> -#include <linux/stringify.h>
>  #include <linux/zalloc.h>
>  #include <sys/types.h>
>  #include <sys/stat.h>
>  #include <fcntl.h>
>  #include <stdlib.h>
>  #include <string.h>
> +#include <api/fs/fs.h>
>  
>  int nr_cgroups;
>  
> -static int
> -cgroupfs_find_mountpoint(char *buf, size_t maxlen)
> -{
> -	FILE *fp;
> -	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
> -	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
> -	char *token, *saved_ptr = NULL;
> -
> -	fp = fopen("/proc/mounts", "r");
> -	if (!fp)
> -		return -1;
> -
> -	/*
> -	 * in order to handle split hierarchy, we need to scan /proc/mounts
> -	 * and inspect every cgroupfs mount point to find one that has
> -	 * perf_event subsystem
> -	 */
> -	path_v1[0] = '\0';
> -	path_v2[0] = '\0';
> -
> -	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
> -				__stringify(PATH_MAX)"s %*d %*d\n",
> -				mountpoint, type, tokens) == 3) {
> -
> -		if (!path_v1[0] && !strcmp(type, "cgroup")) {
> -
> -			token = strtok_r(tokens, ",", &saved_ptr);
> -
> -			while (token != NULL) {
> -				if (!strcmp(token, "perf_event")) {
> -					strcpy(path_v1, mountpoint);
> -					break;
> -				}
> -				token = strtok_r(NULL, ",", &saved_ptr);
> -			}
> -		}
> -
> -		if (!path_v2[0] && !strcmp(type, "cgroup2"))
> -			strcpy(path_v2, mountpoint);
> -
> -		if (path_v1[0] && path_v2[0])
> -			break;
> -	}
> -	fclose(fp);
> -
> -	if (path_v1[0])
> -		path = path_v1;
> -	else if (path_v2[0])
> -		path = path_v2;
> -	else
> -		return -1;
> -
> -	if (strlen(path) < maxlen) {
> -		strcpy(buf, path);
> -		return 0;
> -	}
> -	return -1;
> -}
> -
>  static int open_cgroup(const char *name)
>  {
>  	char path[PATH_MAX + 1];
> @@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
>  	int fd;
>  
>  
> -	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
> +	if (cgroupfs__mountpoint(mnt, PATH_MAX + 1, "perf_event"))
>  		return -1;
>  
>  	scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
> -- 
> 2.25.0.341.g760bfbb309-goog
> 

Re: [PATCH v2] tools lib api fs: Move cgroupsfs__mountpoint()

[Arnaldo Carvalho de Melo]

Em Tue, Jan 28, 2020 at 10:40:57AM +0100, Jiri Olsa escreveu:
> On Tue, Jan 28, 2020 at 09:49:40AM +0900, Namhyung Kim wrote:
> > Move it from tools/perf/util/cgroup.c as it can be used by other places.
> > Note that cgroup filesystem is different from others since it's usually
> > mounted separately (in v1) for each subsystem.
> > 
> > I just copied the code with a little modification to pass a name of
> > subsystem and renamed it to follow other APIs.
> > 
> > Suggested-by: Jiri Olsa <jolsa@redhat.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> 
> Acked-by: Jiri Olsa <jolsa@redhat.com>

Thanks, applied to perf/core.

- Arnaldo
 
> thanks,
> jirka
> 
> > ---
> > * rename to cgroupfs__mountpoint()
> > 
> >  tools/lib/api/fs/Build    |  1 +
> >  tools/lib/api/fs/cgroup.c | 67 +++++++++++++++++++++++++++++++++++++++
> >  tools/lib/api/fs/fs.h     |  2 ++
> >  tools/perf/util/cgroup.c  | 63 ++----------------------------------
> >  4 files changed, 72 insertions(+), 61 deletions(-)
> >  create mode 100644 tools/lib/api/fs/cgroup.c
> > 
> > diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
> > index f4ed9629ae85..0f75b28654de 100644
> > --- a/tools/lib/api/fs/Build
> > +++ b/tools/lib/api/fs/Build
> > @@ -1,2 +1,3 @@
> >  libapi-y += fs.o
> >  libapi-y += tracing_path.o
> > +libapi-y += cgroup.o
> > diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
> > new file mode 100644
> > index 000000000000..c7e1cdaa36e1
> > --- /dev/null
> > +++ b/tools/lib/api/fs/cgroup.c
> > @@ -0,0 +1,67 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include <linux/stringify.h>
> > +#include <sys/types.h>
> > +#include <sys/stat.h>
> > +#include <fcntl.h>
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include "fs.h"
> > +
> > +int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys)
> > +{
> > +	FILE *fp;
> > +	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
> > +	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
> > +	char *token, *saved_ptr = NULL;
> > +
> > +	fp = fopen("/proc/mounts", "r");
> > +	if (!fp)
> > +		return -1;
> > +
> > +	/*
> > +	 * in order to handle split hierarchy, we need to scan /proc/mounts
> > +	 * and inspect every cgroupfs mount point to find one that has
> > +	 * perf_event subsystem
> > +	 */
> > +	path_v1[0] = '\0';
> > +	path_v2[0] = '\0';
> > +
> > +	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
> > +				__stringify(PATH_MAX)"s %*d %*d\n",
> > +				mountpoint, type, tokens) == 3) {
> > +
> > +		if (!path_v1[0] && !strcmp(type, "cgroup")) {
> > +
> > +			token = strtok_r(tokens, ",", &saved_ptr);
> > +
> > +			while (token != NULL) {
> > +				if (subsys && !strcmp(token, subsys)) {
> > +					strcpy(path_v1, mountpoint);
> > +					break;
> > +				}
> > +				token = strtok_r(NULL, ",", &saved_ptr);
> > +			}
> > +		}
> > +
> > +		if (!path_v2[0] && !strcmp(type, "cgroup2"))
> > +			strcpy(path_v2, mountpoint);
> > +
> > +		if (path_v1[0] && path_v2[0])
> > +			break;
> > +	}
> > +	fclose(fp);
> > +
> > +	if (path_v1[0])
> > +		path = path_v1;
> > +	else if (path_v2[0])
> > +		path = path_v2;
> > +	else
> > +		return -1;
> > +
> > +	if (strlen(path) < maxlen) {
> > +		strcpy(buf, path);
> > +		return 0;
> > +	}
> > +	return -1;
> > +}
> > diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
> > index 92d03b8396b1..07591ecbe39f 100644
> > --- a/tools/lib/api/fs/fs.h
> > +++ b/tools/lib/api/fs/fs.h
> > @@ -28,6 +28,8 @@ FS(bpf_fs)
> >  #undef FS
> >  
> >  
> > +int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys);
> > +
> >  int filename__read_int(const char *filename, int *value);
> >  int filename__read_ull(const char *filename, unsigned long long *value);
> >  int filename__read_xll(const char *filename, unsigned long long *value);
> > diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
> > index 4881d4af3381..12e466d1ec3b 100644
> > --- a/tools/perf/util/cgroup.c
> > +++ b/tools/perf/util/cgroup.c
> > @@ -3,75 +3,16 @@
> >  #include "evsel.h"
> >  #include "cgroup.h"
> >  #include "evlist.h"
> > -#include <linux/stringify.h>
> >  #include <linux/zalloc.h>
> >  #include <sys/types.h>
> >  #include <sys/stat.h>
> >  #include <fcntl.h>
> >  #include <stdlib.h>
> >  #include <string.h>
> > +#include <api/fs/fs.h>
> >  
> >  int nr_cgroups;
> >  
> > -static int
> > -cgroupfs_find_mountpoint(char *buf, size_t maxlen)
> > -{
> > -	FILE *fp;
> > -	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
> > -	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
> > -	char *token, *saved_ptr = NULL;
> > -
> > -	fp = fopen("/proc/mounts", "r");
> > -	if (!fp)
> > -		return -1;
> > -
> > -	/*
> > -	 * in order to handle split hierarchy, we need to scan /proc/mounts
> > -	 * and inspect every cgroupfs mount point to find one that has
> > -	 * perf_event subsystem
> > -	 */
> > -	path_v1[0] = '\0';
> > -	path_v2[0] = '\0';
> > -
> > -	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
> > -				__stringify(PATH_MAX)"s %*d %*d\n",
> > -				mountpoint, type, tokens) == 3) {
> > -
> > -		if (!path_v1[0] && !strcmp(type, "cgroup")) {
> > -
> > -			token = strtok_r(tokens, ",", &saved_ptr);
> > -
> > -			while (token != NULL) {
> > -				if (!strcmp(token, "perf_event")) {
> > -					strcpy(path_v1, mountpoint);
> > -					break;
> > -				}
> > -				token = strtok_r(NULL, ",", &saved_ptr);
> > -			}
> > -		}
> > -
> > -		if (!path_v2[0] && !strcmp(type, "cgroup2"))
> > -			strcpy(path_v2, mountpoint);
> > -
> > -		if (path_v1[0] && path_v2[0])
> > -			break;
> > -	}
> > -	fclose(fp);
> > -
> > -	if (path_v1[0])
> > -		path = path_v1;
> > -	else if (path_v2[0])
> > -		path = path_v2;
> > -	else
> > -		return -1;
> > -
> > -	if (strlen(path) < maxlen) {
> > -		strcpy(buf, path);
> > -		return 0;
> > -	}
> > -	return -1;
> > -}
> > -
> >  static int open_cgroup(const char *name)
> >  {
> >  	char path[PATH_MAX + 1];
> > @@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
> >  	int fd;
> >  
> >  
> > -	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
> > +	if (cgroupfs__mountpoint(mnt, PATH_MAX + 1, "perf_event"))
> >  		return -1;
> >  
> >  	scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
> > -- 
> > 2.25.0.341.g760bfbb309-goog
> > 
> 

-- 

- Arnaldo

[tip: perf/core] tools lib api fs: Move cgroupsfs_find_mountpoint()

[tip-bot2 for Namhyung Kim]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     7982a898515064ba180d958bfc89ed22d13905ee
Gitweb:        https://git.kernel.org/tip/7982a898515064ba180d958bfc89ed22d13905ee
Author:        Namhyung Kim <namhyung@kernel.org>
AuthorDate:    Mon, 27 Jan 2020 19:00:31 +09:00
Committer:     Arnaldo Carvalho de Melo <acme@redhat.com>
CommitterDate: Wed, 04 Mar 2020 10:34:09 -03:00

tools lib api fs: Move cgroupsfs_find_mountpoint()

Move it from tools/perf/util/cgroup.c as it can be used by other places.
Note that cgroup filesystem is different from others since it's usually
mounted separately (in v1) for each subsystem.

I just copied the code with a little modification to pass a name of
subsystem.

Suggested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200127100031.1368732-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/lib/api/fs/Build    |  1 +-
 tools/lib/api/fs/cgroup.c | 67 ++++++++++++++++++++++++++++++++++++++-
 tools/lib/api/fs/fs.h     |  2 +-
 tools/perf/util/cgroup.c  | 63 +-----------------------------------
 4 files changed, 72 insertions(+), 61 deletions(-)
 create mode 100644 tools/lib/api/fs/cgroup.c

diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
index f4ed962..0f75b28 100644
--- a/tools/lib/api/fs/Build
+++ b/tools/lib/api/fs/Build
@@ -1,2 +1,3 @@
 libapi-y += fs.o
 libapi-y += tracing_path.o
+libapi-y += cgroup.o
diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
new file mode 100644
index 0000000..889a6eb
--- /dev/null
+++ b/tools/lib/api/fs/cgroup.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/stringify.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "fs.h"
+
+int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
+{
+	FILE *fp;
+	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
+	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
+	char *token, *saved_ptr = NULL;
+
+	fp = fopen("/proc/mounts", "r");
+	if (!fp)
+		return -1;
+
+	/*
+	 * in order to handle split hierarchy, we need to scan /proc/mounts
+	 * and inspect every cgroupfs mount point to find one that has
+	 * perf_event subsystem
+	 */
+	path_v1[0] = '\0';
+	path_v2[0] = '\0';
+
+	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
+				__stringify(PATH_MAX)"s %*d %*d\n",
+				mountpoint, type, tokens) == 3) {
+
+		if (!path_v1[0] && !strcmp(type, "cgroup")) {
+
+			token = strtok_r(tokens, ",", &saved_ptr);
+
+			while (token != NULL) {
+				if (subsys && !strcmp(token, subsys)) {
+					strcpy(path_v1, mountpoint);
+					break;
+				}
+				token = strtok_r(NULL, ",", &saved_ptr);
+			}
+		}
+
+		if (!path_v2[0] && !strcmp(type, "cgroup2"))
+			strcpy(path_v2, mountpoint);
+
+		if (path_v1[0] && path_v2[0])
+			break;
+	}
+	fclose(fp);
+
+	if (path_v1[0])
+		path = path_v1;
+	else if (path_v2[0])
+		path = path_v2;
+	else
+		return -1;
+
+	if (strlen(path) < maxlen) {
+		strcpy(buf, path);
+		return 0;
+	}
+	return -1;
+}
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 92d03b8..936edb9 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -28,6 +28,8 @@ FS(bpf_fs)
 #undef FS
 
 
+int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys);
+
 int filename__read_int(const char *filename, int *value);
 int filename__read_ull(const char *filename, unsigned long long *value);
 int filename__read_xll(const char *filename, unsigned long long *value);
diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
index 4881d4a..5bc9d3b 100644
--- a/tools/perf/util/cgroup.c
+++ b/tools/perf/util/cgroup.c
@@ -3,75 +3,16 @@
 #include "evsel.h"
 #include "cgroup.h"
 #include "evlist.h"
-#include <linux/stringify.h>
 #include <linux/zalloc.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
+#include <api/fs/fs.h>
 
 int nr_cgroups;
 
-static int
-cgroupfs_find_mountpoint(char *buf, size_t maxlen)
-{
-	FILE *fp;
-	char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
-	char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
-	char *token, *saved_ptr = NULL;
-
-	fp = fopen("/proc/mounts", "r");
-	if (!fp)
-		return -1;
-
-	/*
-	 * in order to handle split hierarchy, we need to scan /proc/mounts
-	 * and inspect every cgroupfs mount point to find one that has
-	 * perf_event subsystem
-	 */
-	path_v1[0] = '\0';
-	path_v2[0] = '\0';
-
-	while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
-				__stringify(PATH_MAX)"s %*d %*d\n",
-				mountpoint, type, tokens) == 3) {
-
-		if (!path_v1[0] && !strcmp(type, "cgroup")) {
-
-			token = strtok_r(tokens, ",", &saved_ptr);
-
-			while (token != NULL) {
-				if (!strcmp(token, "perf_event")) {
-					strcpy(path_v1, mountpoint);
-					break;
-				}
-				token = strtok_r(NULL, ",", &saved_ptr);
-			}
-		}
-
-		if (!path_v2[0] && !strcmp(type, "cgroup2"))
-			strcpy(path_v2, mountpoint);
-
-		if (path_v1[0] && path_v2[0])
-			break;
-	}
-	fclose(fp);
-
-	if (path_v1[0])
-		path = path_v1;
-	else if (path_v2[0])
-		path = path_v2;
-	else
-		return -1;
-
-	if (strlen(path) < maxlen) {
-		strcpy(buf, path);
-		return 0;
-	}
-	return -1;
-}
-
 static int open_cgroup(const char *name)
 {
 	char path[PATH_MAX + 1];
@@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
 	int fd;
 
 
-	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
+	if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
 		return -1;
 
 	scnprintf(path, PATH_MAX, "%s/%s", mnt, name);