From ab85785aa13c36440a91a8e9f7616357de411a1f Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 6 Jul 2015 08:51:41 -0300 Subject: [PATCH] tools lib api debugfs: Check for tracefs when reporting errors Now that we have two mountpoints, one for debugfs and another, for tracefs, we end up needing to check permissions for both, so, on a system with default config we were always asking the user to check the permission of the debugfs mountpoint, even when it was already sufficient. Fix it. E.g.: $ trace -e nanosleep usleep 1 Error: No permissions to read /sys/kernel/debug/tracing/events/raw_syscalls/sys_(enter|exit) Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug' $ sudo mount -o remount,mode=755 /sys/kernel/debug $ trace -e nanosleep usleep 1 Error: No permissions to read /sys/kernel/debug/tracing/events/raw_syscalls/sys_(enter|exit) Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing' $ sudo mount -o remount,mode=755 /sys/kernel/debug/tracing $ trace -e nanosleep usleep 1 0.326 ( 0.061 ms): usleep/11961 nanosleep(rqtp: 0x7ffef1081c50) = 0 $ Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Steven Rostedt Link: http://lkml.kernel.org/n/tip-0viljeuhc7q84ic8kobsna43@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/debugfs.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/tools/lib/api/fs/debugfs.c b/tools/lib/api/fs/debugfs.c index 8305b3e9d48e..eb7cf4d18f8a 100644 --- a/tools/lib/api/fs/debugfs.c +++ b/tools/lib/api/fs/debugfs.c @@ -12,6 +12,7 @@ #include #include "debugfs.h" +#include "tracefs.h" #ifndef DEBUGFS_DEFAULT_PATH #define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug" @@ -94,11 +95,21 @@ int debugfs__strerror_open(int err, char *buf, size_t size, const char *filename "Hint:\tIs the debugfs filesystem mounted?\n" "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'"); break; - case EACCES: + case EACCES: { + const char *mountpoint = debugfs_mountpoint; + + if (!access(debugfs_mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) { + const char *tracefs_mntpoint = tracefs_find_mountpoint(); + + if (tracefs_mntpoint) + mountpoint = tracefs_mntpoint; + } + snprintf(buf, size, "Error:\tNo permissions to read %s/%s\n" "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n", - debugfs_mountpoint, filename, debugfs_mountpoint); + debugfs_mountpoint, filename, mountpoint); + } break; default: snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf))); -- 2.30.2