From: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>,
Chris Wedgwood <cw@f00f.org>
If UML wants to open an xterm channel and the xterm does not run properly (eg.
terminates soon after starting) we will get a hang (a comment added in the
patch explains why).
This avoids the most common cause for this and adds a comment (which long term
will go away with a rewrite of that code); the complete fix would be to catch
the xterm process dying, up(&data->sem), and -EIO all requests from that point
onwards.
That applies for some of the other channels too, so part of the code should
probably be abstracted a little and generalized.
Signed-off-by: Chris Wedgwood <cw@f00f.org>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/um/drivers/xterm.c | 7 +++++++
25-akpm/arch/um/drivers/xterm_kern.c | 9 ++++++++-
2 files changed, 15 insertions(+), 1 deletion(-)
diff -puN arch/um/drivers/xterm.c~uml-fail-xterm_open-when-we-have-no-display arch/um/drivers/xterm.c
--- 25/arch/um/drivers/xterm.c~uml-fail-xterm_open-when-we-have-no-display Thu Jan 13 15:27:10 2005
+++ 25-akpm/arch/um/drivers/xterm.c Thu Jan 13 15:27:10 2005
@@ -97,6 +97,13 @@ int xterm_open(int input, int output, in
if(os_access(argv[4], OS_ACC_X_OK) < 0)
argv[4] = "port-helper";
+ /* Check that DISPLAY is set, this doesn't guarantee the xterm
+ * will work but w/o it we can be pretty sure it won't. */
+ if (!getenv("DISPLAY")) {
+ printk("xterm_open: $DISPLAY not set.\n");
+ return -ENODEV;
+ }
+
fd = mkstemp(file);
if(fd < 0){
printk("xterm_open : mkstemp failed, errno = %d\n", errno);
diff -puN arch/um/drivers/xterm_kern.c~uml-fail-xterm_open-when-we-have-no-display arch/um/drivers/xterm_kern.c
--- 25/arch/um/drivers/xterm_kern.c~uml-fail-xterm_open-when-we-have-no-display Thu Jan 13 15:27:10 2005
+++ 25-akpm/arch/um/drivers/xterm_kern.c Thu Jan 13 15:27:10 2005
@@ -46,6 +46,8 @@ int xterm_fd(int socket, int *pid_out)
printk(KERN_ERR "xterm_fd : failed to allocate xterm_wait\n");
return(-ENOMEM);
}
+
+ /* This is a locked semaphore... */
*data = ((struct xterm_wait)
{ .sem = __SEMAPHORE_INITIALIZER(data->sem, 0),
.fd = socket,
@@ -55,12 +57,17 @@ int xterm_fd(int socket, int *pid_out)
err = um_request_irq(XTERM_IRQ, socket, IRQ_READ, xterm_interrupt,
SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM,
"xterm", data);
- if(err){
+ if (err){
printk(KERN_ERR "xterm_fd : failed to get IRQ for xterm, "
"err = %d\n", err);
ret = err;
goto out;
}
+
+ /* ... so here we wait for an xterm interrupt.
+ *
+ * XXX Note, if the xterm doesn't work for some reason (eg. DISPLAY
+ * isn't set) this will hang... */
down(&data->sem);
free_irq_by_irq_and_dev(XTERM_IRQ, data);
_