From 4dbed85a35ed37d9608f4f32e5d69efa775d6223 Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Mon, 17 Dec 2007 16:19:46 -0800 Subject: uml: stop gdb from deleting breakpoints when running UML Sometimes when UML is debugged gdb miss breakpoints. When process traced by gdb do fork, debugger remove breakpoints from child address space. There is possibility to trace more than one fork, but this not work with UML, I guess (only guess) there is a deadlock - gdb waits for UML and UML waits for gdb. When clone() is called with SIGCHLD and CLONE_VM flags, gdb see this as PTRACE_EVENT_FORK not as PTRACE_EVENT_CLONE and remove breakpoints from child and at the same time from traced process, because either have the same address space. Maybe it is possible to do fix in gdb, but I'm not sure if there is easy way to find out if traced and child processes share memory. So I do fix for UML, it simply do not call clone() with both SIGCHLD and CLONE_VM flags together. Additionally __WALL flag is used for waitpid() to assure not miss clone and normal process events. [ jdike - checkpatch fixes ] Signed-off-by: Stanislaw Gruszka Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/os-Linux/util.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/um/os-Linux/util.c') diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c index ef095436a78..3e058ce9ffb 100644 --- a/arch/um/os-Linux/util.c +++ b/arch/um/os-Linux/util.c @@ -141,7 +141,7 @@ void os_dump_core(void) * nothing reasonable to do if that fails. */ - while ((pid = waitpid(-1, NULL, WNOHANG)) > 0) + while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0) os_kill_ptraced_process(pid, 0); abort(); -- cgit v1.2.3