kernel/tools/perf/util/cgroup.c, branch linux-4.17.y

perf tools: Fix snprint warnings for gcc 8

2018-03-19T13:00:43Z

With gcc 8 we get new set of snprintf() warnings that breaks the compilation, one example: tests/mem.c: In function ‘check’: tests/mem.c:19:48: error: ‘%s’ directive output may be truncated writing \ up to 99 bytes into a region of size 89 [-Werror=format-truncation=] snprintf(failure, sizeof failure, "unexpected %s", out); The gcc docs says: To avoid the warning either use a bigger buffer or handle the function's return value which indicates whether or not its output has been truncated. Given that all these warnings are harmless, because the code either properly fails due to uncomplete file path or we don't care for truncated output at all, I'm changing all those snprintf() calls to scnprintf(), which actually 'checks' for the snprint return value so the gcc stays silent. Signed-off-by: Jiri Olsa Cc: Alexander Shishkin Cc: David Ahern Cc: Josh Poimboeuf Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Sergey Senozhatsky Link: http://lkml.kernel.org/r/20180319082902.4518-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Make the cgroup name be const char *

2018-03-07T13:22:26Z

The usual thing is for a constructor to allocate space for its members, not to require that the caller pass a pre-allocated 'name' and then, at its destructor, to free something not allocated by it. Fix it by making cgroup__new() to receive a const char pointer, then allocate cgroup->name that then can continue to be freed at cgroup__delete(), balancing the alloc/free operations inside the cgroup struct methods. This eases calling evlist__findnew_cgroup() from the custom 'perf trace' cgroup parser, that will only call parse_cgroups() when the '-G cgroup' is passed on the command line after '-e event' entries, when it'll behave just like 'perf stat' and 'perf record', i.e. the previous parse_cgroup() users that mandate that -G only can come after a -e. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-4leugnuyqi10t98990o3xi1t@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Add evlist__add_default_cgroup()

2018-03-07T13:22:26Z

So that tools like 'perf trace' can allow the user to set a cgroup to be used for all the evsels still without a crgroup setup by parse_cgroups(), such as the one to use for the syscalls, vfs_getname and other events involved in strace like syscall tracing. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-zf9jjsbj661r3lk6qb7g8j70@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Add evlist__findnew_cgroup()

2018-03-07T13:22:26Z

Similar to machine__findnew_thread(), etc, i.e. try to find, get a refcount if found and return it, otherwise return a new cgroup object. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-im1omevlihhyneiic4nl3g24@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Introduce cgroup__new() out of open coded equivalent

2018-03-07T13:22:25Z

To follow the namespacing convention in tools/perf. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-jaalyl6bkvvji4r5u8wqw4n4@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Introduce find_cgroup() method

2018-03-07T13:22:25Z

To break down complexity in add_cgroup(). Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-5yqshcf5hm837n7c86u7lhjf@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Introduce cgroup__get()

2018-03-07T13:22:25Z

The refcount operation counterpart to cgroup__put(), use it when reusing a cgroup. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-14ynvrl7y2cz8gyuy5q5v41g@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Rename close_cgroup() to cgroup__put()

2018-03-07T13:22:25Z

It is not really closing the cgroup, but instead dropping a reference count and if it hits zero, then calling delete, which will, among other cleanup shores, close the cgroup fd. So it is really dropping a reference to that cgroup, and the method name for that is "put", so rename close_cgroup() to cgroup__put() to follow this naming convention. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-sccxpnd7bgwc1llgokt6fcey@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Introduce cgroup__delete()

2018-03-07T13:22:25Z

Just to make this code look more like other places in tools/perf. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-j3j72vvn2d5j7tenlghdy195@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf cgroup: Rename 'struct cgroup_sel' to 'struct cgroup'

2018-03-07T13:22:25Z

That name isn't used, is shorter, lets switch to it. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-e51yphwgvepd1y4f5fjptmjq@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo