Patchwork [v2] osdep: Fix runtime failure on older Linux kernels

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Submitter Andre Przywara
Date Dec. 18, 2009, 12:37 p.m.
Message ID <1261139878-28751-1-git-send-email-andre.przywara@amd.com>
Download mbox | patch
Permalink /patch/41400/
State New
Headers show

Comments

Andre Przywara - Dec. 18, 2009, 12:37 p.m.
If QEMU finds newer kernel header files on compilation time, it will use
advertised features like pipe2 or SOCK_CLOEXEC by just doing a compile test.
If later the executables are executed on an older kernel (<2.6.27,
like Xen Dom0 2.6.18), then QEMU will fail on opening sockets and creating
pipes and returns the rather unspecific "qemu_init_main_loop failed".
This patch fixes this by checking the return values of these calls
for EINVAL and ENOSYS and falling back to the older versions automatically.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
---
 osdep.c |   18 ++++++++++++------
 1 files changed, 12 insertions(+), 6 deletions(-)

v2 changed the errno check from EINVAL to ENOSYS for accept4
Kevin Wolf - Dec. 18, 2009, 12:49 p.m.
Am 18.12.2009 13:37, schrieb Andre Przywara:
> If QEMU finds newer kernel header files on compilation time, it will use
> advertised features like pipe2 or SOCK_CLOEXEC by just doing a compile test.
> If later the executables are executed on an older kernel (<2.6.27,
> like Xen Dom0 2.6.18), then QEMU will fail on opening sockets and creating
> pipes and returns the rather unspecific "qemu_init_main_loop failed".
> This patch fixes this by checking the return values of these calls
> for EINVAL and ENOSYS and falling back to the older versions automatically.
> 
> Signed-off-by: Andre Przywara <andre.przywara@amd.com>
> ---
>  osdep.c |   18 ++++++++++++------
>  1 files changed, 12 insertions(+), 6 deletions(-)
> 
> v2 changed the errno check from EINVAL to ENOSYS for accept4

Acked-by: Kevin Wolf <kwolf@redhat.com>

I think this patch even qualifies for stable, though this might mean
0.12.1 now.

Kevin

Patch

diff --git a/osdep.c b/osdep.c
index 7509c5b..60469ed 100644
--- a/osdep.c
+++ b/osdep.c
@@ -262,13 +262,15 @@  int qemu_pipe(int pipefd[2])
 
 #ifdef CONFIG_PIPE2
     ret = pipe2(pipefd, O_CLOEXEC);
-#else
+    if (ret != -1 || errno != ENOSYS) {
+        return ret;
+    }
+#endif
     ret = pipe(pipefd);
     if (ret == 0) {
         qemu_set_cloexec(pipefd[0]);
         qemu_set_cloexec(pipefd[1]);
     }
-#endif
 
     return ret;
 }
@@ -283,12 +285,14 @@  int qemu_socket(int domain, int type, int protocol)
 
 #ifdef SOCK_CLOEXEC
     ret = socket(domain, type | SOCK_CLOEXEC, protocol);
-#else
+    if (ret != -1 || errno != EINVAL) {
+        return ret;
+    }
+#endif
     ret = socket(domain, type, protocol);
     if (ret >= 0) {
         qemu_set_cloexec(ret);
     }
-#endif
 
     return ret;
 }
@@ -302,12 +306,14 @@  int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen)
 
 #ifdef CONFIG_ACCEPT4
     ret = accept4(s, addr, addrlen, SOCK_CLOEXEC);
-#else
+    if (ret != -1 || errno != ENOSYS) {
+        return ret;
+    }
+#endif
     ret = accept(s, addr, addrlen);
     if (ret >= 0) {
         qemu_set_cloexec(ret);
     }
-#endif
 
     return ret;
 }