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| author | Vegard Nossum <vegard.nossum@oracle.com> | 2015-12-18 21:28:53 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2016-02-13 10:34:08 +0000 |
| commit | 15dabec9d87dd441d6f0ce49fbbef7fcc5f1ec39 (patch) | |
| tree | c20e89d9bb8cc265661997e68d724d93191ae6fc /arch | |
| parent | edde646c29cc1729088935ee187f6ec733d61d62 (diff) | |
| download | linux-rt-15dabec9d87dd441d6f0ce49fbbef7fcc5f1ec39.tar.gz | |
uml: flush stdout before forking
commit 0754fb298f2f2719f0393491d010d46cfb25d043 upstream.
I was seeing some really weird behaviour where piping UML's output
somewhere would cause output to get duplicated:
$ ./vmlinux | head -n 40
Checking that ptrace can change system call numbers...Core dump limits :
soft - 0
hard - NONE
OK
Checking syscall emulation patch for ptrace...Core dump limits :
soft - 0
hard - NONE
OK
Checking advanced syscall emulation patch for ptrace...Core dump limits :
soft - 0
hard - NONE
OK
Core dump limits :
soft - 0
hard - NONE
This is because these tests do a fork() which duplicates the non-empty
stdout buffer, then glibc flushes the duplicated buffer as each child
exits.
A simple workaround is to flush before forking.
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/um/os-Linux/start_up.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index 2f53b892fd80..c8993dfbe8e1 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -95,6 +95,8 @@ static int start_ptraced_child(void) { int pid, n, status; + fflush(stdout); + pid = fork(); if (pid == 0) ptrace_child(); |