[ovs-dev] [PATCH v5 1/2] util: Support checking for kernel versions.

[Felix Huettner via dev]

Extract checking for a given kernel version to a separate function.
It will be used also in the next patch.

Signed-off-by: Felix Huettner <felix.huettner@mail.schwarz>
---
v4->v5:
- fix wrong ifdef that broke on macos
- fix ovs_kernel_is_version_or_newer working in reverse than desired
- ovs_kernel_is_version_or_newer now always returns false if uname
  errors (Thanks Eelco)
v4:
- extract function to check kernel version
 lib/netdev-linux.c | 14 +++-----------
 lib/util.c         | 27 +++++++++++++++++++++++++++
 lib/util.h         |  4 ++++
 3 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index bf91ef462..51bd71ae3 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -6427,18 +6427,10 @@ getqdisc_is_safe(void)
     static bool safe = false;
 
     if (ovsthread_once_start(&once)) {
-        struct utsname utsname;
-        int major, minor;
-
-        if (uname(&utsname) == -1) {
-            VLOG_WARN("uname failed (%s)", ovs_strerror(errno));
-        } else if (!ovs_scan(utsname.release, "%d.%d", &major, &minor)) {
-            VLOG_WARN("uname reported bad OS release (%s)", utsname.release);
-        } else if (major < 2 || (major == 2 && minor < 35)) {
-            VLOG_INFO("disabling unsafe RTM_GETQDISC in Linux kernel %s",
-                      utsname.release);
-        } else {
+        if (ovs_kernel_is_version_or_newer(2, 35)) {
             safe = true;
+        } else {
+            VLOG_INFO("disabling unsafe RTM_GETQDISC in Linux kernel");
         }
         ovsthread_once_done(&once);
     }
diff --git a/lib/util.c b/lib/util.c
index 3fb3a4b40..f5b2da095 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -27,6 +27,7 @@
 #include <string.h>
 #ifdef __linux__
 #include <sys/prctl.h>
+#include <sys/utsname.h>
 #endif
 #include <sys/stat.h>
 #include <unistd.h>
@@ -2500,3 +2501,29 @@ OVS_CONSTRUCTOR(winsock_start) {
    }
 }
 #endif
+
+#ifdef __linux__
+bool
+ovs_kernel_is_version_or_newer(int target_major, int target_minor)
+{
+    static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
+    static int current_major, current_minor = -1;
+
+    if (ovsthread_once_start(&once)) {
+        struct utsname utsname;
+
+        if (uname(&utsname) == -1) {
+            VLOG_WARN("uname failed (%s)", ovs_strerror(errno));
+        } else if (!ovs_scan(utsname.release, "%d.%d",
+                    &current_major, &current_minor)) {
+            VLOG_WARN("uname reported bad OS release (%s)", utsname.release);
+        }
+        ovsthread_once_done(&once);
+    }
+    if (current_major == -1 || current_minor == -1) {
+        return false;
+    }
+    return current_major > target_major || (
+            current_major == target_major && current_minor > target_minor);
+}
+#endif
diff --git a/lib/util.h b/lib/util.h
index f2d45bcac..55718fd87 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -611,4 +611,8 @@ int ftruncate(int fd, off_t length);
 }
 #endif
 
+#ifdef __linux__
+bool ovs_kernel_is_version_or_newer(int target_major, int target_minor);
+#endif
+
 #endif /* util.h */

base-commit: 166ee41d282c506d100bc2185d60af277121b55b
-- 
2.43.2

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