uml: fix spurious IRQ testing

The spurious IRQ testing in request_irq is mishandled in um_request_irq, which
sets the incoming file descriptors non-blocking only after request_irq
succeeds.  This results in the spurious irq calling read on a blocking
descriptor, and a hang.

Fixed by reversing the O_NONBLOCK setting and the request_irq call.

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/kernel/irq.c b/arch/um/kernel/irq.c
index 70c2d62..ba11ccd 100644 (file)
--- a/arch/um/kernel/irq.c
+++ b/arch/um/kernel/irq.c
@@ -347,14 +347,15 @@ int um_request_irq(unsigned int irq, int fd, int type,
 {
        int err;
 
-       err = request_irq(irq, handler, irqflags, devname, dev_id);
-       if (err)
-               return err;
-
-       if (fd != -1)
+       if (fd != -1) {
                err = activate_fd(irq, fd, type, dev_id);
-       return err;
+               if (err)
+                       return err;
+       }
+
+       return request_irq(irq, handler, irqflags, devname, dev_id);
 }
+
 EXPORT_SYMBOL(um_request_irq);
 EXPORT_SYMBOL(reactivate_fd);