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 <stf_xl@wp.pl>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/os-Linux/drivers/ethertap_user.c b/arch/um/os-Linux/drivers/ethertap_user.c
index 4ff5536..07ca0cb 100644
--- a/arch/um/os-Linux/drivers/ethertap_user.c
+++ b/arch/um/os-Linux/drivers/ethertap_user.c
@@ -94,7 +94,7 @@
int control_remote, int data_me, int data_remote)
{
struct etap_pre_exec_data pe_data;
- int pid, status, err, n;
+ int pid, err, n;
char version_buf[sizeof("nnnnn\0")];
char data_fd_buf[sizeof("nnnnnn\0")];
char gate_buf[sizeof("nnn.nnn.nnn.nnn\0")];
@@ -131,13 +131,7 @@
}
if (c != 1) {
printk(UM_KERN_ERR "etap_tramp : uml_net failed\n");
- err = -EINVAL;
- CATCH_EINTR(n = waitpid(pid, &status, 0));
- if (n < 0)
- err = -errno;
- else if (!WIFEXITED(status) || (WEXITSTATUS(status) != 1))
- printk(UM_KERN_ERR "uml_net didn't exit with "
- "status 1\n");
+ err = helper_wait(pid, 0, "uml_net");
}
return err;
}
diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index 6c55d3c..1037a3b6 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -107,7 +107,7 @@
"errno = %d\n", errno);
return err;
}
- CATCH_EINTR(waitpid(pid, NULL, 0));
+ helper_wait(pid, 0, "tuntap_open_tramp");
cmsg = CMSG_FIRSTHDR(&msg);
if (cmsg == NULL) {