linux/tools/lib
Tiezhu Yang b48543c451 perf list: Give clues if failed to open tracing events directory
When executing the command "perf list", I met "Error: failed to open
tracing events directory" twice, the first reason is that there is no
"/sys/kernel/tracing/events" directory due to it does not enable the
kernel tracing infrastructure with CONFIG_FTRACE, the second reason
is that there is no root privileges.

Add the error string to tell the users what happened and what should
to do, and also call put_tracing_file() to free events_path a little
later to avoid messy code in the error message.

At the same time, just remove the redundant "/" of the file path in
the function get_tracing_file(), otherwise it shows something like
"/sys/kernel/tracing//events".

Before:

  $ ./perf list
  Error: failed to open tracing events directory

After:

(1) Without CONFIG_FTRACE

  $ ./perf list
  Error: failed to open tracing events directory
  /sys/kernel/tracing/events: No such file or directory

(2) With CONFIG_FTRACE but no root privileges

  $ ./perf list
  Error: failed to open tracing events directory
  /sys/kernel/tracing/events: Permission denied

Committer testing:

Redirect stdout to null to quickly test the patch:

Before:

  $ perf list > /dev/null
  Error: failed to open tracing events directory
  $

After:

  $ perf list > /dev/null
  Error: failed to open tracing events directory
  /sys/kernel/tracing/events: Permission denied
  $

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/20240730062301.23244-3-yangtiezhu@loongson.cn
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2024-08-01 12:11:33 -03:00
..
api perf list: Give clues if failed to open tracing events directory 2024-08-01 12:11:33 -03:00
bpf libbpf: Fix no-args func prototype BTF dumping syntax 2024-07-17 22:42:47 +02:00
perf libperf: Add gitignore 2024-08-01 12:11:33 -03:00
subcmd tools lib subcmd: Show parent options in help 2024-05-12 21:09:52 -03:00
symbol tools lib symbol: Add dependency test to install_headers 2022-12-14 11:16:12 -03:00
thermal tools/lib/thermal: Fix include path for libnl3 in pkg-config file. 2023-02-15 17:29:40 +01:00
argv_split.c
bitmap.c radix tree test suite: put definition of bitmap_clear() into lib/bitmap.c 2024-07-10 14:24:27 -07:00
ctype.c
find_bit.c tools: sync find_bit() implementation 2022-09-21 12:21:44 -07:00
hweight.c
list_sort.c tools/lib/list_sort: remove redundant code for cond_resched handling 2024-06-24 22:25:04 -07:00
rbtree.c tools lib rbtree: pick some improvements from the kernel rbtree code 2024-05-08 08:41:27 -07:00
slab.c tools: Move gfp.h and slab.h from radix-tree to lib 2022-02-20 08:44:37 +02:00
str_error_r.c
string.c perf annotate: Add disasm_line__parse() to parse raw instruction for powerpc 2024-07-31 16:12:59 -03:00
vsprintf.c
zalloc.c