* Re: [PATCH] tools lib api fs: Store tracing mountpoint for better error message
2015-09-19 14:47 [PATCH] tools lib api fs: Store tracing mountpoint for better error message Jiri Olsa
@ 2015-09-19 14:50 ` David Ahern
2015-09-19 15:00 ` Jiri Olsa
2015-09-19 15:26 ` Raphaël Beamonte
2015-09-29 8:38 ` [tip:perf/core] " tip-bot for Jiri Olsa
2 siblings, 1 reply; 6+ messages in thread
From: David Ahern @ 2015-09-19 14:50 UTC (permalink / raw)
To: Jiri Olsa, Arnaldo Carvalho de Melo
Cc: lkml, Ingo Molnar, Namhyung Kim, Peter Zijlstra, Matt Fleming,
Raphaël Beamonte
On 9/19/15 8:47 AM, Jiri Olsa wrote:
> diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
> index 38aca2dd1946..0406a7d5c891 100644
> --- a/tools/lib/api/fs/tracing_path.c
> +++ b/tools/lib/api/fs/tracing_path.c
> @@ -12,12 +12,14 @@
> #include "tracing_path.h"
>
>
> +char tracing_mnt[PATH_MAX + 1] = "/sys/kernel/debug";
> char tracing_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing";
> char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
why all the +1s? null terminator has to fit within PATH_MAX as well.
>
>
> static void __tracing_path_set(const char *tracing, const char *mountpoint)
> {
> + snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
> snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
> mountpoint, tracing);
> snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
> @@ -109,19 +111,10 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename)
> "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
> break;
> case EACCES: {
> - const char *mountpoint = debugfs__mountpoint();
> -
> - if (!access(mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {
> - const char *tracefs_mntpoint = tracefs__mountpoint();
> -
> - if (tracefs_mntpoint)
> - mountpoint = tracefs__mountpoint();
> - }
> -
> snprintf(buf, size,
> "Error:\tNo permissions to read %s/%s\n"
> "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
> - tracing_events_path, filename, mountpoint);
> + tracing_events_path, filename, tracing_mnt);
> }
> break;
> default:
>
LGTM.
David
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] tools lib api fs: Store tracing mountpoint for better error message
2015-09-19 14:50 ` David Ahern
@ 2015-09-19 15:00 ` Jiri Olsa
2015-09-19 15:23 ` Raphaël Beamonte
0 siblings, 1 reply; 6+ messages in thread
From: Jiri Olsa @ 2015-09-19 15:00 UTC (permalink / raw)
To: David Ahern
Cc: Jiri Olsa, Arnaldo Carvalho de Melo, lkml, Ingo Molnar,
Namhyung Kim, Peter Zijlstra, Matt Fleming,
Raphaël Beamonte
On Sat, Sep 19, 2015 at 08:50:19AM -0600, David Ahern wrote:
> On 9/19/15 8:47 AM, Jiri Olsa wrote:
>
> >diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
> >index 38aca2dd1946..0406a7d5c891 100644
> >--- a/tools/lib/api/fs/tracing_path.c
> >+++ b/tools/lib/api/fs/tracing_path.c
> >@@ -12,12 +12,14 @@
> > #include "tracing_path.h"
> >
> >
> >+char tracing_mnt[PATH_MAX + 1] = "/sys/kernel/debug";
> > char tracing_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing";
> > char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
>
> why all the +1s? null terminator has to fit within PATH_MAX as well.
good question.. can't see a reason ATM
jirka
>
> >
> >
> > static void __tracing_path_set(const char *tracing, const char *mountpoint)
> > {
> >+ snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
> > snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
> > mountpoint, tracing);
> > snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
> >@@ -109,19 +111,10 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename)
> > "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
> > break;
> > case EACCES: {
> >- const char *mountpoint = debugfs__mountpoint();
> >-
> >- if (!access(mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {
> >- const char *tracefs_mntpoint = tracefs__mountpoint();
> >-
> >- if (tracefs_mntpoint)
> >- mountpoint = tracefs__mountpoint();
> >- }
> >-
> > snprintf(buf, size,
> > "Error:\tNo permissions to read %s/%s\n"
> > "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
> >- tracing_events_path, filename, mountpoint);
> >+ tracing_events_path, filename, tracing_mnt);
> > }
> > break;
> > default:
> >
>
> LGTM.
>
> David
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] tools lib api fs: Store tracing mountpoint for better error message
2015-09-19 15:00 ` Jiri Olsa
@ 2015-09-19 15:23 ` Raphaël Beamonte
0 siblings, 0 replies; 6+ messages in thread
From: Raphaël Beamonte @ 2015-09-19 15:23 UTC (permalink / raw)
To: Jiri Olsa
Cc: David Ahern, Jiri Olsa, Arnaldo Carvalho de Melo, lkml,
Ingo Molnar, Namhyung Kim, Peter Zijlstra, Matt Fleming
2015-09-19 11:00 GMT-04:00 Jiri Olsa <jolsa@redhat.com>:
> On Sat, Sep 19, 2015 at 08:50:19AM -0600, David Ahern wrote:
>> On 9/19/15 8:47 AM, Jiri Olsa wrote:
>>
>> >diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
>> >index 38aca2dd1946..0406a7d5c891 100644
>> >--- a/tools/lib/api/fs/tracing_path.c
>> >+++ b/tools/lib/api/fs/tracing_path.c
>> >@@ -12,12 +12,14 @@
>> > #include "tracing_path.h"
>> >
>> >
>> >+char tracing_mnt[PATH_MAX + 1] = "/sys/kernel/debug";
>> > char tracing_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing";
>> > char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
>>
>> why all the +1s? null terminator has to fit within PATH_MAX as well.
>
> good question.. can't see a reason ATM
It is quite weird actually, it seems there is multiple occurrences of
that, without any comment to explain why that +1, even if the #define
of PATH_MAX in limits.h specify that that size also counts nul.
Most of these occurrences are linked to perf though, but there's also
fs/ocfs2/aops.c, scripts/docproc.c and usr/gen_init_cpio.c.
Perhaps a mistake that started somewhere and that was propagated
looking at the original mistake?
> jirka
>
>>
>> >
>> >
>> > static void __tracing_path_set(const char *tracing, const char *mountpoint)
>> > {
>> >+ snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
>> > snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
>> > mountpoint, tracing);
>> > snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
>> >@@ -109,19 +111,10 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename)
>> > "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
>> > break;
>> > case EACCES: {
>> >- const char *mountpoint = debugfs__mountpoint();
>> >-
>> >- if (!access(mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {
>> >- const char *tracefs_mntpoint = tracefs__mountpoint();
>> >-
>> >- if (tracefs_mntpoint)
>> >- mountpoint = tracefs__mountpoint();
>> >- }
>> >-
>> > snprintf(buf, size,
>> > "Error:\tNo permissions to read %s/%s\n"
>> > "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
>> >- tracing_events_path, filename, mountpoint);
>> >+ tracing_events_path, filename, tracing_mnt);
>> > }
>> > break;
>> > default:
>> >
>>
>> LGTM.
>>
>> David
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tools lib api fs: Store tracing mountpoint for better error message
2015-09-19 14:47 [PATCH] tools lib api fs: Store tracing mountpoint for better error message Jiri Olsa
2015-09-19 14:50 ` David Ahern
@ 2015-09-19 15:26 ` Raphaël Beamonte
2015-09-29 8:38 ` [tip:perf/core] " tip-bot for Jiri Olsa
2 siblings, 0 replies; 6+ messages in thread
From: Raphaël Beamonte @ 2015-09-19 15:26 UTC (permalink / raw)
To: Jiri Olsa
Cc: Arnaldo Carvalho de Melo, lkml, David Ahern, Ingo Molnar,
Namhyung Kim, Peter Zijlstra, Matt Fleming
2015-09-19 10:47 GMT-04:00 Jiri Olsa <jolsa@kernel.org>:
> Storing the actual tracing path mountpoint to display correct
> error message hint ('Hint:' line). The error hint rediscovers
> mountpoints, but it could be different from what we actually
> used in tracing path.
>
> Before we'd display debugfs mount even though tracefs was used:
> $ perf record -e sched:sched_krava ls
> event syntax error: 'sched:sched_krava'
> \___ can't access trace events
>
> Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
> Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
> ...
>
> After this change, correct mountpoint is displayed:
> $ perf record -e sched:sched_krava ls
> event syntax error: 'sched:sched_krava'
> \___ can't access trace events
>
> Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
> Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
> ...
>
> Link: http://lkml.kernel.org/n/tip-xw7mf64ie0svh6m449vbyh0m@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/lib/api/fs/tracing_path.c | 13 +++----------
> 1 file changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
> index 38aca2dd1946..0406a7d5c891 100644
> --- a/tools/lib/api/fs/tracing_path.c
> +++ b/tools/lib/api/fs/tracing_path.c
> @@ -12,12 +12,14 @@
> #include "tracing_path.h"
>
>
> +char tracing_mnt[PATH_MAX + 1] = "/sys/kernel/debug";
> char tracing_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing";
> char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
>
>
> static void __tracing_path_set(const char *tracing, const char *mountpoint)
> {
> + snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
> snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
> mountpoint, tracing);
> snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
> @@ -109,19 +111,10 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename)
> "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
> break;
> case EACCES: {
> - const char *mountpoint = debugfs__mountpoint();
> -
> - if (!access(mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {
> - const char *tracefs_mntpoint = tracefs__mountpoint();
> -
> - if (tracefs_mntpoint)
> - mountpoint = tracefs__mountpoint();
> - }
> -
> snprintf(buf, size,
> "Error:\tNo permissions to read %s/%s\n"
> "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
> - tracing_events_path, filename, mountpoint);
> + tracing_events_path, filename, tracing_mnt);
> }
> break;
> default:
> --
> 2.4.3
>
Reviewed-by: Raphaël Beamonte <raphael.beamonte@gmail.com>
^ permalink raw reply [flat|nested] 6+ messages in thread* [tip:perf/core] tools lib api fs: Store tracing mountpoint for better error message
2015-09-19 14:47 [PATCH] tools lib api fs: Store tracing mountpoint for better error message Jiri Olsa
2015-09-19 14:50 ` David Ahern
2015-09-19 15:26 ` Raphaël Beamonte
@ 2015-09-29 8:38 ` tip-bot for Jiri Olsa
2 siblings, 0 replies; 6+ messages in thread
From: tip-bot for Jiri Olsa @ 2015-09-29 8:38 UTC (permalink / raw)
To: linux-tip-commits
Cc: dsahern, a.p.zijlstra, linux-kernel, tglx, jolsa, matt, acme,
hpa, raphael.beamonte, mingo, namhyung
Commit-ID: dc240c5dc2a02e335c5bcb50ad3a1274818c8609
Gitweb: http://git.kernel.org/tip/dc240c5dc2a02e335c5bcb50ad3a1274818c8609
Author: Jiri Olsa <jolsa@kernel.org>
AuthorDate: Sat, 19 Sep 2015 16:47:07 +0200
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 28 Sep 2015 15:50:54 -0300
tools lib api fs: Store tracing mountpoint for better error message
Storing the actual tracing path mountpoint to display correct
error message hint ('Hint:' line). The error hint rediscovers
mountpoints, but it could be different from what we actually
used in tracing path.
Before we'd display debugfs mount even though tracefs was used:
$ perf record -e sched:sched_krava ls
event syntax error: 'sched:sched_krava'
\___ can't access trace events
Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
...
After this change, correct mountpoint is displayed:
$ perf record -e sched:sched_krava ls
event syntax error: 'sched:sched_krava'
\___ can't access trace events
Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_krava
Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
...
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Raphael Beamonte <raphael.beamonte@gmail.com>
Link: http://lkml.kernel.org/r/1442674027-19427-1-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/lib/api/fs/tracing_path.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)
diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
index 38aca2d..0406a7d 100644
--- a/tools/lib/api/fs/tracing_path.c
+++ b/tools/lib/api/fs/tracing_path.c
@@ -12,12 +12,14 @@
#include "tracing_path.h"
+char tracing_mnt[PATH_MAX + 1] = "/sys/kernel/debug";
char tracing_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing";
char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events";
static void __tracing_path_set(const char *tracing, const char *mountpoint)
{
+ snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
mountpoint, tracing);
snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
@@ -109,19 +111,10 @@ static int strerror_open(int err, char *buf, size_t size, const char *filename)
"Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
break;
case EACCES: {
- const char *mountpoint = debugfs__mountpoint();
-
- if (!access(mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {
- const char *tracefs_mntpoint = tracefs__mountpoint();
-
- if (tracefs_mntpoint)
- mountpoint = tracefs__mountpoint();
- }
-
snprintf(buf, size,
"Error:\tNo permissions to read %s/%s\n"
"Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
- tracing_events_path, filename, mountpoint);
+ tracing_events_path, filename, tracing_mnt);
}
break;
default:
^ permalink raw reply [flat|nested] 6+ messages in thread