perf tools: Do parameter validation earlier on fetch_kernel_version()

While trying to reduce util.[ch] I noticed that fetch_kernel_version()
and fetch_ubuntu_kernel_version() do lots of operations only to check if
they are needed, i.e. it checks if the pointer where to return the
kernel version is NULL only after obtaining the kernel version from
/proc/version_signature or by parsing the results from uname().

Do it earlier not to confuse people reading this code in the future :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-i94qwyekk4tzbu0b9ce1r1mz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 3cd42995ac6f76f17419110b7889c9421c2e14bb..988111e0bab592369ecf197d43127dab0dc57975 100644 (file)
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -350,8 +350,12 @@ fetch_ubuntu_kernel_version(unsigned int *puint)
        size_t line_len = 0;
        char *ptr, *line = NULL;
        int version, patchlevel, sublevel, err;
-       FILE *vsig = fopen("/proc/version_signature", "r");
+       FILE *vsig;
 
+       if (!puint)
+               return 0;
+
+       vsig = fopen("/proc/version_signature", "r");
        if (!vsig) {
                pr_debug("Open /proc/version_signature failed: %s\n",
                         strerror(errno));
@@ -381,8 +385,7 @@ fetch_ubuntu_kernel_version(unsigned int *puint)
                goto errout;
        }
 
-       if (puint)
-               *puint = (version << 16) + (patchlevel << 8) + sublevel;
+       *puint = (version << 16) + (patchlevel << 8) + sublevel;
        err = 0;
 errout:
        free(line);
@@ -409,6 +412,9 @@ fetch_kernel_version(unsigned int *puint, char *str,
                str[str_size - 1] = '\0';
        }
 
+       if (!puint || int_ver_ready)
+               return 0;
+
        err = sscanf(utsname.release, "%d.%d.%d",
                     &version, &patchlevel, &sublevel);
 
@@ -418,8 +424,7 @@ fetch_kernel_version(unsigned int *puint, char *str,
                return -1;
        }
 
-       if (puint && !int_ver_ready)
-               *puint = (version << 16) + (patchlevel << 8) + sublevel;
+       *puint = (version << 16) + (patchlevel << 8) + sublevel;
        return 0;
 }