Messages in this thread | | | From | Raphaël Beamonte <> | Date | Sat, 19 Sep 2015 11:23:53 -0400 | Subject | Re: [PATCH] tools lib api fs: Store tracing mountpoint for better error message |
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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
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